Ink set for thermal transfer sheet, thermal transfer sheet, method for producing thermal transfer sheet, and method for producing transfer printed matter

Abstract

To provide a thermal transfer sheet excellent in image transferability, an ink set for the thermal transfer sheet, a method for manufacturing the thermal transfer sheet, and a method for manufacturing a transfer printed matter.SOLUTION: An ink set for a thermal transfer sheet comprising a white ink and a non-white ink, wherein the white ink comprises a water-dispersible resin (A) and water, and the water-dispersible resin (A) has a heat melting temperature of 100 °C or lower.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to an ink set for a thermal transfer sheet, a thermal transfer sheet, a method for producing a thermal transfer sheet, and a method for producing a transfer-printed matter. [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 of DTF printing is the formation of a transfer image without any missing parts. The method described in Patent Document 1 uses a special grade of hot melt powder to prevent image loss, and a highly impermeable substrate sheet to ensure the adhesion of the hot melt powder. However, the preferred grade of hot melt powder has a small particle size and is prone to scattering, making it difficult to handle. Furthermore, the use of a highly impermeable substrate sheet tends to cause color mixing between the color inks forming the image and the white ink applied thereon, which presents another challenge in that image reproducibility is easily impaired.

[0006] An object of the present disclosure is to provide a thermal transfer sheet with excellent image transferability, an ink set for the thermal transfer sheet, a method for manufacturing a thermal transfer sheet, and a method for manufacturing a transfer-printed material. [Means for solving the problem]

[0007] One embodiment of the present disclosure relates to an ink set for a thermal transfer sheet, which includes a white ink and a non-white ink, wherein the white ink includes a water-dispersible resin (A) and water, and the water-dispersible resin (A) has a thermal melting temperature of 100°C or less.

[0008] Another embodiment of the present disclosure relates to a thermal transfer sheet having a printed portion with a non-white ink and a printed portion with a white ink, the white ink containing a water-dispersible resin (A) and water, and the water-dispersible resin (A) having a thermal melting temperature of 100°C or less.

[0009] Another embodiment of the present disclosure relates to a method for producing a thermal transfer sheet, which includes applying a non-white ink onto a base sheet and then applying a white ink by a wet-on-wet method, wherein the white ink contains a water-dispersible resin (A) and water, and the water-dispersible resin (A) has a thermal melting temperature of 100°C or less.

[0010] Another embodiment of the present disclosure relates to a method for producing a transfer printed matter, which includes placing the above-mentioned thermal transfer sheet on a cloth, heating the cloth to transfer an image, and peeling off the base sheet. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to provide a thermal transfer sheet with excellent image transferability, an ink set for a thermal transfer sheet, a method for manufacturing a thermal transfer sheet, and a method for manufacturing a transfer-printed item. DETAILED DESCRIPTION OF THE INVENTION

[0012] 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.

[0013] An ink set for thermal transfer sheets in one embodiment (hereinafter sometimes referred to as the "ink set") comprises a white ink and a non-white ink, the white ink comprising a water-dispersible resin (A) and water, the water-dispersible resin (A) having a thermal melting temperature of 100° C. or less. In one embodiment of the ink set, since the water-dispersible resin (A) contained in the white ink has a thermal melting temperature of 100° C. or less, when a thermal transfer sheet having an image formed by the ink set is used to produce a transfer printed matter, the white ink penetrates the fabric appropriately without using a hot melt powder, and an anchoring effect can be obtained while maintaining the image quality of the transferred image, resulting in a thermal transfer sheet with excellent image transferability.

[0014] The water-dispersible resin (A) contained in the white ink (hereinafter sometimes referred to as "resin (A)") may be any resin as long as it has a thermal melting temperature of 100°C or less, and various resins can be used without any particular limitations. Furthermore, one type of resin (A) may be used alone, or two or more types may be used in combination.

[0015] The heat melting temperature of the resin (A) is more preferably 80°C or lower, and particularly preferably 70°C or lower, because this provides a more pronounced anchoring effect on the fabric. Furthermore, the heat melting temperature of the resin (A) is preferably 30°C or higher, more preferably 40°C or higher, and particularly preferably 50°C or higher, because this provides an excellent balance between the anchoring effect on the fabric and the image quality of the transferred image. The heat melting temperature of the resin (A) may be in the range of 30 to 100°C.

[0016] In this disclosure, the thermal melting temperature of a resin is the half-wave temperature calculated from a flow curve measured by a temperature rise test using a high-speed flow tester in accordance with JIS K7121: 2012. Examples of the flow tester that can be used include the high-speed flow tester CFT-500D manufactured by Shimadzu Corporation.

[0017] Resin (A) is preferably one capable of forming a transparent coating film, as this results in a white ink with superior color development. Specific examples of resin (A) 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 carboxyl group; melamine resins; urea resins; polyurethane resins; polyester resins; polyolefin resins; silicone resins; polyvinyl butyral resins; and alkyd resins. Among these, polyurethane resins are preferred because of their superior anchoring effect on fabrics.

[0018] Examples of water-dispersible resins with a thermal melting temperature of 100°C or less include "Superflex 500M" (thermal melting temperature 67°C), "Superflex 740" (thermal melting temperature 53°C), and "Superflex 860" (thermal melting temperature 93°C) manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

[0019] The content of resin (A) in the white ink is preferably 5% by mass or more, more preferably 8% by mass or more, and particularly preferably 12% by mass or more, because this provides better image quality and washing fastness in transfer-printed materials. It may also be 30% by mass or less, 25% by mass or less, or 20% by mass or less. The content of resin (A) in the white ink may be in the range of 5 to 30% by mass.

[0020] Examples of water contained in the white ink include ion-exchanged water, distilled water, ultrapure water, etc. The water content 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.

[0021] 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.

[0022] 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, in the range of 1 to 30% by mass of the total amount of the white ink.

[0023] 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 polymer dispersants and surfactant-type dispersants.

[0024] Examples of commercially available polymer dispersants include the TEGO Disperse series ("TEGO Disperse 740W", "TEGO Disperse 750W", "TEGO Disperse 755W", "TEGO Disperse 757W", "TEGO Disperse 760W", etc.) from EVONIK, and the Solsperse series ("Solsperse 20000", "Solsperse 27000", "Solsperse 41000", "Solsperse 41090", "Solsperse 43000", "Solsperse 44000", "Solsperse 45000", "Solsperse 46000", "Solsperse 47000", "Solsperse 48000", "Solsperse 49000", "Solsperse 5000", "Solsperse 51000", "Solsperse 52000", "Solsperse 53000", "Solsperse 54000", "Solsperse 55000", "Solsperse 56000", "Solsperse 57000", "Solsperse 58000", "Solsperse 59000", "Solsperse 6000", "Solsperse 61000", "Solsperse 62000", "Solsperse 63000", "Solsperse 64000", "Solsperse 65000", "Solsperse 66000", "Solsperse 67000", "Solsperse 68000", "Solsperse 69000", "Solsperse 7000", "Sol 6000), BASF Japan Ltd.'s JONCRYL series (JONCRYL 57, JONCRYL 60, JONCRYL 62, JONCRYL 63, JONCRYL 71, JONCRYL 501, etc.), BYK-Chemie Japan Ltd.'s DISPERBYK-102, DISPERBYK-185, DISPERBYK-190, DISPERBYK-193, DISPERBYK-199, etc., Daiichi Kogyo Seiyaku Co., Ltd.'s Polyvinylpyrrolidone K-30, Polyvinylpyrrolidone K-90, etc.

[0025] Examples of surfactant-type dispersants include commercially available anionic surfactants such as Kao Corporation's Demol series ("Demol P," "Demol EP," "Demol N," "Demol RN," "Demol NL," "Demol RNL," "Demol T-45," etc.); and nonionic surfactants such as Kao Corporation's Emulgen series ("Emulgen A-60," "Emulgen A-90," "Emulgen A-500," "Emulgen B-40," "Emulgen L-40," "Emulgen 420," etc.).

[0026] When a pigment dispersant is used, the amount used is adjusted appropriately depending on the types of white pigment and pigment dispersant, but may be, for example, in the range of 0.05 to 20 parts by mass per 100 parts by mass of the white pigment.

[0027] The white ink may contain other components in addition to the resin (A), water, and white colorant, such as surfactants, water-soluble organic solvents, pH adjusters, fixing agents, and preservatives.

[0028] 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 10 to 20.

[0029] 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; and fluorine-based surfactants.

[0030] Of these, it is preferable that the white ink contains a silicone surfactant, in order to obtain a higher quality transferred image. Examples of silicone surfactants include polyether-modified silicone surfactants, alkyl-aralkyl co-modified silicone surfactants, and acrylic silicone surfactants. Examples of commercially available silicone surfactants include "Silface SAG002" and "Silface SAG503A" manufactured by Nissin Chemical Industry Co., Ltd.

[0031] The content of the silicone surfactant in the white ink may be, for example, 0.05% by mass or more, 0.1% by mass or more, or 0.5% by mass or more. It may also be 10% by mass or less, 5% by mass or less, or 3% by mass or less. The content of the silicone surfactant in the white ink may be in the range of 0.05 to 10% by mass.

[0032] Furthermore, in order to obtain a transfer printed matter with even better washing fastness, it is preferable that the white ink contains polyoxyethylene alkyl ether. The number of repeating units in the oxyethylene chain of the polyoxyethylene alkyl ether may be 10 or more, 12 or more, or 16 or more. It may also be 30 or less, 28 or less, or 24 or less. The number of repeating units in the oxyethylene chain of the polyoxyethylene alkyl ether may be in the range of 10 to 30. The number of carbon atoms in the alkyl group of the polyoxyethylene alkyl ether may be 10 or more, 12 or more, or 14 or more. It may also be 30 or less, 26 or less, or 22 or less. The number of carbon atoms in the alkyl group of the polyoxyethylene alkyl ether may be in the range of 10 to 30.

[0033] The polyoxyethylene alkyl ether content of the white ink may be, for example, 0.05% by mass or more, 0.1% by mass or more, or 0.5% by mass or more. It may also be 10% by mass or less, 8% by mass or less, or 5% by mass or less. The polyoxyethylene alkyl ether content of the white ink may be in the range of 0.05 to 10% by mass.

[0034] As the water-soluble organic solvent, those commonly used in the field of aqueous inks can be used without any particular limitation. The water-soluble organic solvent may be used alone or in combination of two or more. 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.

[0035] 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 30% by mass or less, 25% by mass or less, or 20% by mass or less. The content of the water-soluble organic solvent in the white ink may be in the range of 1 to 30% by mass.

[0036] 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.

[0037] 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.

[0038] In one embodiment, the ink set includes a non-white ink. The ink set may include one or more non-white inks.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] Examples of self-dispersing pigments include Cabot Corporation's "CAB-O-JET" series ("CAB-O-JET200," "CAB-O-JET300," "CAB-O-JET250C," "CAB-O-JET260M," "CAB-O-JET270Y," "CAB-O-JET450C," and "CAB-O-JET465M," etc.), and Orient Chemical Industries Co., Ltd.'s "BONJET" series ("BONJET BLACK CW-1," "BONJET BLACK CW-2," "BONJET BLACK CW-3," "BONJET BLACK CW-4," etc.).

[0044] 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.

[0045] 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.

[0046] 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. Specific examples of pigment dispersants include those exemplified in the description of the white ink.

[0047] 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 non-white ink may be a water-based ink, similar to the white ink. In this case, the non-white ink preferably contains a water-dispersible resin (B) (hereinafter, this may be referred to as "resin (B)") and water.

[0048] The thermal melting temperature of resin (B) is preferably the same as or higher than the thermal melting temperature of resin (A), and more preferably higher than the thermal melting temperature of resin (A). When the thermal melting temperature of resin (B) is higher than the thermal melting temperature of resin (A), mixing of white ink and non-white ink is less likely to occur during transfer, and a transferred image of higher quality can be obtained. The difference between the thermal melting temperature of resin (B) and the thermal melting temperature of resin (A) may be 0°C or higher, 50°C or higher, or 100°C or higher. It may also be 200°C or lower, 180°C or lower, or 160°C or lower. The difference between the thermal melting temperature of resin (B) and the thermal melting temperature of resin (A) may be in the range of 0 to 200°C.

[0049] Resin (B) is preferably one capable of forming a transparent coating film, since it results in a non-white ink with superior color development. Specific examples of resin (B) 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. Among these, polyurethane resins are preferred because of their excellent adhesion to white ink images.

[0050] Examples of water-dispersible resins include the polyurethane dispersion "DAOTAN" series (e.g., "DAOTAN TW6450," "DAOTAN TW6460," "DAOTAN TW6490," "DAOTAN VTW1262," etc.) manufactured by Daicel Allnex Corporation, and the "Implanil" series (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" manufactured by Sumika Covestro Urethane Co., Ltd. 1069, Impranil DLN-W50, etc.), Daiichi Kogyo Seiyaku's "Superflex" series (e.g., "Superflex 420", "Superflex 150HS", "Superflex 460", "Superflex 470", "Superflex E2000", "Superflex 740", "Superflex 500M", "Superflex 300", "Superflex 860", 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.), BYK's "AQUACER" series (for example, "AQUACER507"), and Japan Coating Resins Co., Ltd.'s "Mowinyl" series (for example, "Mowinyl 6750", "Mowinyl 6751D", "Mowinyl 6763", "Mowinyl 6770", "Mowinyl 6775", etc.).

[0051] The content of resin (B) in the non-white ink is adjusted appropriately depending on the type of pigment, etc., but may be, for example, 5% by mass or more, 8% by mass or more, or 10% by mass or more. It may also be 30% by mass or less, 25% by mass or less, or 20% by mass or less. The content of resin (B) in the non-white ink may be in the range of 5 to 30% by mass.

[0052] Examples of water contained in non-white ink include ion-exchanged water, distilled water, ultrapure water, etc. The water content 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.

[0053] The non-white ink may contain other components in addition to the non-white colorant, resin (B), and water, such as surfactants, water-soluble organic solvents, pH adjusters, fixing agents, and preservatives.

[0054] Specific examples of surfactants include those exemplified in the explanation of the white ink. A single type of surfactant may be used, or two or more types may be used in combination. Among these, it is preferable that the non-white ink contains a silicone surfactant, in order to obtain a transfer print with even better image quality. Examples of silicone surfactants include polyether-modified silicone surfactants, alkyl / aralkyl-co-modified silicone surfactants, and acrylic silicone surfactants. Examples of commercially available silicone surfactants include "Silface SAG002" and "Silface SAG503A" manufactured by Nissin Chemical Industry Co., Ltd.

[0055] The content of the silicone surfactant in the non-white ink may be, for example, 0.05% by mass or more, 0.1% by mass or more, or 0.5% by mass or more. It may also be 10% by mass or less, 5% by mass or less, or 3% by mass or less. The content of the silicone surfactant in the non-white ink may be in the range of 0.05 to 10% by mass.

[0056] Specific examples of water-soluble organic solvents include those exemplified in the description of the white ink. One type of water-soluble organic solvent may be used alone, or two or more types may be used in combination. 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 35% by mass or less, 30% by mass or less, or 25% by mass or less. The content of the water-soluble organic solvent in the non-white ink may be in the range of 1 to 35% by mass.

[0057] There are no particular limitations on the method for producing the non-white ink, and the non-white ink can be produced by the same method as the white ink.

[0058] 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.

[0059] In addition to the white ink and non-white ink, the ink set of an embodiment may also include a clear ink, a pre-treatment liquid, a post-treatment liquid, etc. The clear ink, the pre-treatment liquid, and the post-treatment liquid may each be, for example, a liquid that is commonly used in the field of aqueous inkjet inks.

[0060] One embodiment of the thermal transfer sheet has a printed area with a non-white ink and a printed area with a white ink, the white ink containing a water-dispersible resin (A) and water, the water-dispersible resin (A) having a thermal melting temperature of 100°C or lower. In one embodiment of the thermal transfer sheet, the resin (A) contained in the white ink has a thermal melting temperature of 100°C or lower, which gives the white ink-printed area hot melt properties and allows it to penetrate the fabric adequately during thermal transfer, achieving an anchoring effect while maintaining image reproducibility. This allows for the formation of a transfer image without any missing parts, even without the use of hot melt powder, and also provides a transfer print that has excellent washing fastness.

[0061] In the thermal transfer sheet, the white ink and non-white ink are the same as those described above. That is, the printed areas of the thermal transfer sheet using non-white inks and the printed areas of the white ink can be formed using the ink set described above.

[0062] The thermal transfer sheet may have a hot melt powder layer, as with general thermal transfer sheets. For example, a wide variety of hot melt powders commonly used for DTF printing can be used. On the other hand, as mentioned above, the thermal transfer sheet does not need to have a hot melt powder layer because the white ink-printed portion has hot melt properties and plays a role similar to that of a hot melt powder layer. In other words, the thermal transfer sheet may be a hot melt powder-free type that does not use hot melt powder.

[0063] The thermal transfer sheet of one embodiment can be produced by the method for producing a thermal transfer sheet of another embodiment. The method for producing a thermal transfer sheet of one embodiment includes applying a non-white ink onto a substrate sheet and then applying a white ink by a wet-on-wet method, the white ink containing a water-dispersible resin (A) and water, and the water-dispersible resin (A) has a thermal melting temperature of 100°C or less.

[0064] In the method for producing a thermal transfer sheet, the white ink and non-white ink are the same as those described above, that is, the thermal transfer sheet can be produced using the ink set described above.

[0065] The type of substrate sheet is not particularly limited, and may be any type 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. Specific examples of the substrate sheet include those commonly used as substrate sheets for DTF printing. Furthermore, a primer layer, an easily peelable layer, etc. may be provided on the printing surface of the substrate sheet.

[0066] Among the substrate sheets, those having a primer layer containing a cationic resin are preferred because they have excellent color development and can produce high-quality transferred images. The primer layer may contain one or more types of cationic resin. Examples of the cationic resin include cationic urethane resin, cationic acrylic resin, and polyallylamine resin. Specific examples of polyallylamine type resins 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, polydiallylamine, polydiallylamine sulfate, polydiallylamine hydrochloride, polymethyldiallylamine amide, polymethyldiallylamine amide sulfate, polymethyldiallylamine amide hydrochloride, polydiallylamine sulfur dioxide copolymer, polydiallylamine sulfur dioxide copolymer sulfate, polydiallylamine sulfur dioxide copolymer hydrochloride, polymethyldiallylamine sulfur dioxide copolymer, polymethyldiallylamine sulfur dioxide copolymer sulfate, polymethyldiallylamine sulfur dioxide copolymer hydrochloride, and polydimethyldiallylammonium chloride.

[0067] The cationic resin preferably contains a polyallylamine resin, since this provides a highly uniform image density and a high-quality transferred image. Furthermore, it is preferable to use a combination of a polyallylamine resin and a cationic acrylic resin. In this case, the proportion of the polyallylamine resin relative to the total mass of the polyallylamine resin and the cationic acrylic resin may be 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, 30% by mass or less, or 20% by mass or less. The proportion of the polyallylamine resin relative to the total mass of the polyallylamine resin and the cationic acrylic resin may be in the range of 1 to 50% by mass.

[0068] The thickness of the primer layer on the substrate sheet may be, for example, in the range of 1 to 10 μm. The primer layer can be formed, for example, by applying a coating liquid containing a cationic resin onto the substrate sheet and drying it.

[0069] The method for applying the non-white ink onto the substrate sheet is not particularly limited, and application can be performed by various printing methods such as screen printing, roller printing, and inkjet printing. Among these, application can be performed 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 any method such as a piezoelectric method, an electrostatic method, or a thermal method can be used. Application of each ink and ink condensate by the inkjet method can be performed, 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.

[0070] 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., but is, for example, 5 to 50 g / m 2 When multiple types of non-white inks are used, the ink density may be in the range of 5 to 50 g / m for each type. 2 may be in the range of

[0071] After the non-white ink is applied, the white ink is applied using a wet-on-wet method. In the wet-on-wet method, the white ink is applied without any particular drying step after the non-white ink is applied. The method for applying the white ink is not particularly limited, and it can be applied using the same method as for the non-white ink.

[0072] The amount of white ink applied can be adjusted as appropriate depending on the type of substrate sheet, the design of the printed image, etc., but for example, 2 ~300g / m 2 The applied amount of white ink may be in the range of 50 g / m 2When the amount of white ink applied is 120 g / m or more, a transferred image with no missing parts and excellent image quality can be obtained even if the transfer sheet does not have a hot melt powder layer. 2 When the amount of white ink applied is 180 g / m or more, the whiteness of the white image and the washing fastness of the transfer print are further improved. 2 If it is equal to or less than this, the solid uniformity of the white image will be even better.

[0073] In the method for producing a thermal transfer sheet, in addition to the non-white ink and the white ink, other materials may be used. Examples of other materials include a pre-treatment liquid applied to the substrate sheet before applying the non-white ink, a post-treatment liquid applied after applying the white ink, and hot melt powder. As described above, the hot melt powder is not essential in the method for producing a thermal transfer sheet of one embodiment, and can be used optionally.

[0074] The method for producing a thermal transfer sheet may include a drying step. The drying step may be performed after the application of the white ink. Furthermore, when a post-treatment liquid is used, the drying step may be performed after the application of the post-treatment liquid. The drying temperature and drying time are optional, but may be, for example, drying at a temperature in the range of 50 to 150°C for approximately 10 seconds to 10 minutes. By drying, 90% by mass or more of the solvent components, such as water and water-soluble organic solvents, contained in the non-white ink and the white ink may be removed.

[0075] In one embodiment, a method for producing a transfer printed matter includes placing the thermal transfer sheet on a cloth, heating the cloth to transfer an image, and peeling off the substrate sheet.

[0076] The fabric is not particularly limited, and a wide variety of fabrics can be used. Examples of fibers constituting the fabric 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.

[0077] The conditions for transfer, such as pressure, temperature, and pressing time, are adjusted as appropriate depending on the type of fabric, etc. For example, when using a FUSION heat press, the pressure condition may be in the range of 3 to 12 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.

[0078] After the image is transferred, it is preferable to cool the transfer print to room temperature before peeling off the substrate sheet.

[0079] Some embodiments of the present disclosure are set forth below. <1> An ink set for a thermal transfer sheet comprising a white ink and a non-white ink, wherein the white ink comprises a water-dispersible resin (A) and water, and the water-dispersible resin (A) has a thermal melting temperature of 100°C or less.

[0080] <2> The water-dispersible resin (A) has a thermal melting temperature of 40°C or higher. <1> An ink set for a thermal transfer sheet according to the present invention.

[0081] <3> the non-white ink contains a water-dispersible resin (B) and water, and the heat melting temperature of the water-dispersible resin (B) is equal to or higher than the heat melting temperature of the water-dispersible resin (A); <1> or <2> 10. An ink set for a thermal transfer sheet according to claim 19.

[0082] <4> The white ink contains a silicone surfactant in addition to the water-dispersible resin (A) and water. <1> ~ <3> 1. An ink set for a thermal transfer sheet according to any one of the preceding items.

[0083] <5> The white ink contains a water-soluble polyoxyethylene alkyl ether in addition to the water-dispersible resin (A) and water. <1> ~ <4> 1. An ink set for a thermal transfer sheet according to any one of the preceding items.

[0084] <6> A thermal transfer sheet having a printed area with a non-white ink and a printed area with a white ink, the white ink containing a water-dispersible resin (A) and water, the water-dispersible resin (A) having a thermal melting temperature of 100°C or less.

[0085] <7> The above-mentioned hot melt powder-free <6> The thermal transfer sheet according to claim 1.

[0086] <8> A method for producing a thermal transfer sheet, comprising applying a non-white ink onto a base sheet and then applying a white ink by a wet-on-wet method, wherein the white ink contains a water-dispersible resin (A) and water, and the water-dispersible resin (A) has a thermal melting temperature of 100°C or less.

[0087] <9> the substrate sheet has a primer layer containing a cationic resin, <7> A method for producing the thermal transfer sheet according to claim 1.

[0088] <10> The above-mentioned hot melt powder-free <8> or <9> A method for producing the thermal transfer sheet according to claim 1.

[0089] <11> The aforementioned <6> or <7> 10. A method for producing a transfer print, comprising: placing the thermal transfer sheet according to claim 1 on a cloth, heating it to transfer an image, and peeling off the base sheet. [Example]

[0090] 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, "%" means "% by mass" unless otherwise specified. The content shown in each table indicates the total amount of raw materials blended as a solution, dispersion, etc.

[0091] In this example, the thermal melting temperature of the resin is the 1 / 2 method temperature calculated from the flow curve measured by a temperature rise test using a high-speed flow tester "CFT-500D" manufactured by Shimadzu Corporation in accordance with JIS K7121:2012.

[0092] [Manufacturing ink sets for thermal transfer sheets] White inks (1) to (4) and (1') and non-white inks (1) to (8) were produced in the following manner, and these were combined to form an ink set for thermal transfer sheets.

[0093] [White ink manufacturing] 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 white inks (1) to (4) and (1′).

[0094] [Table 1]

[0095] The details of the raw materials listed in Table 1 are as follows: White pigment dispersion: 350g of titanium dioxide (Sakai Chemical Industry Co., Ltd. "R62N") as a white pigment and 14g of pigment dispersant (Kao Corporation "Demol EP") (3.5g of active ingredient) were mixed with 636g of ion-exchanged water and dispersed using a bead mill (Shinmaru Enterprises Co., Ltd. "DYNO-MILL KDL A-type") with 0.5mm diameter zirconia beads at a filling rate of 80% and a residence time of 2 minutes. Pigment content: 35% by mass. Water-dispersible resin (A-1): Daiichi Kogyo Seiyaku Co., Ltd. "Superflex 500M", a water dispersion of urethane resin with a thermal melting temperature of 67°C, resin content 45% by mass Water-dispersible resin (A-2): Daiichi Kogyo Seiyaku Co., Ltd. "Superflex 740", a urethane resin water dispersion with a thermal melting temperature of 53°C, resin content 40% by mass Water-dispersible resin (A'): Daiichi Kogyo Seiyaku Co., Ltd. "Superflex 420", a water dispersion of urethane resin with a thermal melting temperature of 205°C, resin content 32% by mass Silicone surfactant: "Silface SAG503A" manufactured by Nissin Chemical Industry Co., Ltd., HLB value 11 Polyoxyethylene alkyl ether: Nikko Chemicals Co., Ltd. "NIKKOL BS-20", water-soluble polyoxyethylene stearyl ether, oxyethylene chain repeat number 20, HLB value 18, melting point 68°C

[0096] [Production of non-white ink] 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 non-white inks (1) to (8).

[0097] [Table 2]

[0098] The details of the raw materials listed in Table 2 are as follows: Black pigment dispersion: Cabot "CAB-O-JET 300", pigment content 15% by weight Cyan pigment dispersion: Cabot "CAB-O-JET 250C", pigment content 10% by weight Magenta pigment dispersion: Cabot "CAB-O-JET 260M", pigment content 10% by weight Yellow pigment dispersion: Cabot Corporation "CAB-O-JET 270Y", pigment content 10% by weight Water-dispersible resin (B-1): Daiichi Kogyo Seiyaku Co., Ltd. "Superflex 420", a water dispersion of urethane resin with a thermal melting temperature of 205°C, resin content 32% by mass Water-dispersible resin (B-2): Daiichi Kogyo Seiyaku Co., Ltd. "Superflex 500M", a water dispersion of urethane resin with a thermal melting temperature of 67°C, resin content 45% by mass Silicone surfactant: "Silface SAG503A" manufactured by Nissin Chemical Industry Co., Ltd., HLB value 11

[0099] [Base sheet] The following two base sheets were used. Base sheet (1): DTF print film manufactured by Toyo Corporation Base sheet (2): A mixture of 90.3 parts by mass of cationic acrylic resin ("NS-625XC" manufactured by Takamatsu Oil & Fat Co., Ltd., resin content 12% by mass) and 9.7% of polyallylamine ("PAA-01" manufactured by Nittobo Medical Co., Ltd., resin content 15% by mass) was applied to the base sheet (1) and dried to form a primer layer with a thickness of 6 μm.

[0100] [Thermal transfer sheet manufacturing] A non-white ink and a white ink were applied sequentially to the substrate sheet using a wet-on-wet method. The inks were applied by inkjet printing using a Mastermind inkjet printer. The non-white ink was applied as a full-color image print, and the white ink was applied as a solid image print. The printed image had a portion of the image where no non-white ink was applied and had a solid image portion of white ink (hereinafter, this may be referred to as a "white solid image"). The sheet was then dried in a thermostatic chamber to evaporate 96% by mass of the solvent component, yielding a thermal transfer sheet. The type of ink used, the amount of ink applied, and the drying temperature and time are shown in Table 3.

[0101] [Production and evaluation of transfer prints] The printed side of the thermal transfer sheet obtained above was placed on a black polyester T-shirt "Glimmer" manufactured by Tom's Co., Ltd., and heat-pressed using a FUSION heat press machine at a pressure setting of 9 psi, 140°C, and 20 seconds. After cooling to room temperature, the base sheet was peeled off to obtain a transfer print. The transfer print was subjected to the following evaluation tests. The results are shown in Table 3.

[0102] [Evaluation of image transferability] The transferred image on the transfer print was visually observed, and the presence or absence of defects was evaluated according to the following criteria. A: No missing images B: Part of the image is missing C: No image is transferred

[0103] [Image quality evaluation 1: Color development of non-white images] The non-white image on the transfer print was visually observed and evaluated according to the following criteria. A: High color development and high color reproducibility of printed images B: Color development is somewhat high, and color reproduction is impaired only in part of the printed image. C: Color development is poor, and mixing of non-white ink and white ink is observed throughout the image.

[0104] [Image quality evaluation 2: Whiteness of white images] The white solid image on the transfer print was visually observed and evaluated according to the following criteria. A: The whiteness is so high that the black color of the T-shirt does not show through at all. B: The whiteness is high, and the black color of the T-shirt is slightly visible. C: The overall whiteness is low, and the black of the T-shirt shows through.

[0105] [Image quality evaluation 3: Solid white image uniformity] The white solid image on the transfer print was visually observed and evaluated according to the following criteria. AA: The solid uniformity is very high, and the entire white solid image is a uniform white. A: The solid image is highly uniform, and although there are some irregularities, the entire white solid image is almost uniform white. B: Solid uniformity is somewhat high, there are some uneven areas, but it can be recognized as a white image C: The solid color is not uniform and unevenness is noticeable.

[0106] [Evaluation of washing fastness of transfer prints] The transfer print was washed according to the AATCC 61 2A standard and then evaluated according to the following criteria. AA: Washing fastness level 4.5 or higher A: Washing fastness level 4 B: Washing fastness level 2.5 to 3.5 C: Washing fastness level 2.0 or less

[0107] [Table 3]

[0108] In Examples 1 to 9, in which the white ink contained resin (A), a transferred image without any missing parts could be formed. On the other hand, in Comparative Example 1, in which the resin contained in the white ink had a thermal melting temperature of more than 100°C, a transferred image could not be obtained. Example 5, in which the white ink contained a water-soluble polyoxyethylene alkyl ether, gave a transfer print that was superior in washing fastness compared to the other examples. Example 8, which used the substrate sheet (2) having a primer layer containing a cationic resin as the substrate sheet, showed more excellent solid white image uniformity than the other examples.

Claims

1. An ink set for a thermal transfer sheet, comprising a white ink and a non-white ink, The white ink contains a water-dispersible resin (A) and water, The ink set for thermal transfer sheets, wherein the water-dispersible resin (A) has a thermal melting temperature of 100°C or less.

2. 2. The ink set for thermal transfer sheets according to claim 1, wherein the water-dispersible resin (A) has a thermal melting temperature of 40°C or higher.

3. 2. The ink set for thermal transfer sheets according to claim 1, wherein the non-white ink comprises a water-dispersible resin (B) and water, and the heat-melting temperature of the water-dispersible resin (B) is higher than the heat-melting temperature of the water-dispersible resin (A).

4. The ink set for a thermal transfer sheet according to claim 1 , wherein the white ink further contains a silicone-based surfactant.

5. 2. The ink set for a thermal transfer sheet according to claim 1, wherein the white ink further contains a water-soluble polyoxyethylene alkyl ether.

6. A portion printed with non-white ink and a portion printed with white ink are included, The white ink contains a water-dispersible resin (A) and water, The thermal transfer sheet, wherein the water-dispersible resin (A) has a thermal melting temperature of 100°C or less.

7. The thermal transfer sheet according to claim 6, which is free of hot melt powder.

8. A method for producing a thermal transfer sheet, comprising applying a non-white ink onto a substrate sheet, and then applying a white ink by a wet-on-wet method, The white ink contains a water-dispersible resin (A) and water, The method for producing a thermal transfer sheet, wherein the water-dispersible resin (A) has a thermal melting temperature of 100°C or less.

9. The method for producing a thermal transfer sheet according to claim 8 , wherein the substrate sheet has a primer layer containing a cationic resin.

10. The method for producing a thermal transfer sheet according to claim 8, which is free of hot melt powder.

11. A method for producing a transfer print, comprising: placing the thermal transfer sheet according to claim 6 or 7 on a cloth, heating the cloth to transfer an image, and peeling off the substrate sheet.

Images