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 capable of obtaining a transfer printed matter excellent in washing fastness even at a low transfer temperature, an ink set for the thermal transfer sheet, a method for manufacturing the thermal transfer sheet, and a method for manufacturing the transfer printed matter.SOLUTION: An ink set for a thermal transfer sheet comprising an aqueous ink and an aqueous adhesive, wherein the aqueous adhesive contains a nonionic surfactant (A), and a content of the nonionic surfactant (A) in the aqueous adhesive is in a range of 1.5 to 10% by mass.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 been gaining attention in recent years 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 is specifically a printing method that uses a thermal transfer sheet. Compared to methods that print directly onto fabric, DTF printing offers advantages such as higher image clarity and a wider selection of printable fabrics and colors.

[0003] Thermal transfer sheets for DTF printing are generally produced by printing the desired image in color on a base sheet, printing white ink on top of the image, applying hot melt powder to the white ink before it dries, and then heating to melt the hot melt powder.Printing on fabric is performed by placing the hot melt powder layer of the thermal transfer sheet on the fabric side and transferring the image using a heat press.

[0004] As a conventional technique relating to thermal transfer sheets for DTF printing using hot melt powder, Patent Document 1 describes an example of using 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 adhesive properties of the resin powder. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-171840 Summary of the Invention [Problem to be solved by the invention]

[0006] 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 makes it easy for the color inks forming the image to mix with the white ink applied thereon, posing another challenge in that image reproducibility is easily impaired.

[0007] As mentioned above, in DTF printing, an image is transferred and printed using a heat press, and from the viewpoint of energy conservation, a lower transfer temperature is preferable. However, when transfer is performed at a low temperature, there are problems such as image loss and a decrease in the wash fastness of the transfer print.

[0008] One of the objectives of the present disclosure is to provide a thermal transfer sheet that can produce a transfer printed matter with excellent washing fastness even at a low transfer temperature, an ink set for the thermal transfer sheet, a method for manufacturing a thermal transfer sheet, and a method for manufacturing a transfer printed matter. [Means for solving the problem]

[0009] One embodiment of the present disclosure relates to an ink set for thermal transfer sheets, which includes an aqueous ink and an aqueous adhesive, wherein the aqueous adhesive includes a nonionic surfactant (A), and the content of the nonionic surfactant (A) in the aqueous adhesive is in the range of 1.5 to 10 mass %.

[0010] Another embodiment of the present disclosure relates to a thermal transfer sheet having a substrate sheet, and an aqueous ink image and an aqueous adhesive application portion formed on the substrate sheet, wherein the aqueous adhesive contains a nonionic surfactant (A) and a resin, and the proportion of the nonionic surfactant (A) to the total mass of the resin is in the range of 8 to 50 mass%.

[0011] Another embodiment of the present disclosure relates to a method for producing a thermal transfer sheet, which includes applying an aqueous ink onto a base sheet and then applying an aqueous adhesive by a wet-on-wet method, wherein the aqueous adhesive contains a nonionic surfactant (A), and the content of the nonionic surfactant (A) in the aqueous adhesive is in the range of 1.5 to 10 mass%.

[0012] 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]

[0013] According to the present disclosure, it is possible to provide a thermal transfer sheet that can produce a transfer printed matter with excellent washing fastness even at a low transfer temperature, an ink set for the thermal transfer sheet, a method for manufacturing a thermal transfer sheet, and a method for manufacturing a transfer printed matter. DETAILED DESCRIPTION OF THE INVENTION

[0014] 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.

[0015] An ink set for thermal transfer sheets (hereinafter sometimes referred to as "ink set") in one embodiment is an ink set for thermal transfer sheets that includes an aqueous ink and an aqueous adhesive, wherein the aqueous adhesive includes a nonionic surfactant (A), and the content of the nonionic surfactant (A) in the aqueous adhesive is in the range of 1.5 to 10 mass %.

[0016] In one embodiment of the ink set, the aqueous adhesive (hereinafter sometimes referred to as "adhesive") contains a nonionic surfactant (A), and the content is relatively high, ranging from 1.5 to 10% by mass. This allows the adhesive-applied portion of the resulting thermal transfer sheet to have adequate fluidity and easily penetrate into fabric, even at low temperatures of around 120°C. This creates an anchoring effect on the adhesive-applied portion of the fabric, improving adhesion of the transferred image to the fabric and allowing for the production of a transfer print with excellent washfastness. Furthermore, because the surfactant component in the adhesive promotes the anchoring effect on the fabric, it becomes possible to select a resin component that is preferable from other perspectives, thereby broadening the scope of adhesive design and further improving, for example, the image quality of the transferred image and its ability to conform to highly stretchable fabrics.

[0017] The content of the nonionic surfactant (A) in the aqueous adhesive is more preferably 2.0% by mass or more, and particularly preferably 2.5% by mass or more, since this allows for a transfer print with even better washing fastness to be obtained. Furthermore, the content is more preferably 8% by mass or less, and particularly preferably 5% by mass or less, since this allows for a transfer print with even better image quality to be obtained. The content of the nonionic surfactant (A) in the aqueous adhesive is more preferably in the range of 2.5 to 5% by mass.

[0018] The nonionic surfactant (A) may be any compound that is nonionic, has a hydrophilic portion and a lipophilic portion, and can function as a surfactant, and its specific structure is not particularly limited. The HLB value of the nonionic surfactant (A) may be, for example, in the range of 10 to 20. One type of nonionic surfactant (A) may be used alone, or two or more types may be used in combination. Specific examples of the nonionic surfactant (A) include ester-type surfactants such as (poly)glycerin fatty acid esters and sorbitan fatty acid esters; ether-type surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, and polyoxypropylene alkyl ethers; ether-ester-type surfactants such as polyoxyethylene sorbitan fatty acid esters; acetylene-based surfactants; silicone-based surfactants; and fluorine-based surfactants.

[0019] Examples of commercially available (poly)glycerin fatty acid esters include "NIKKOL Hexaglyn 1-L," "NIKKOL Decaglyn 1-M," "NIKKOL Decaglyn 1-OV," and "NIKKOL Decaglyn 1-SV" manufactured by Nikko Chemicals Co., Ltd.

[0020] Examples of polyoxyethylene sorbitan fatty acid esters include "NIKKOL TL-10," "NIKKOL TI-10V," and "NIKKOL TO-10V" manufactured by Nikko Chemicals Co., Ltd.

[0021] With respect to polyoxyethylene alkyl ether, the number of repeating units of the oxyethylene chain is not particularly limited, but may be, for example, in the range of 10 to 30. The number of carbon atoms in the alkyl group of the polyoxyethylene alkyl ether may be in the range of 10 to 30. Examples of commercially available polyoxyethylene alkyl ethers include "NIKKOL BT-12," "NIKKOL BO-20V," "NIKKOL BS-20," "NIKKOL BB-20," and "NIKKOL BC-20" from Nikko Chemicals Co., Ltd., and "EMULGEN 120," "EMULGEN 150," "EMULGEN 350," "EMULGEN 430," "EMULGEN 707," and "EMULGEN 709" from Kao Corporation.

[0022] Examples of acetylene surfactants include acetylene glycol surfactants, acetylene alcohol surfactants, and surfactants 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. 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.).

[0023] 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.

[0024] Examples of nonionic fluorine-based surfactants include perfluoroalkyl alkylene oxide adducts, perfluoroalkyl group-containing oligomers, etc. Examples of commercially available fluorine-based surfactants include perfluoroalkyl ethylene oxide adducts such as "Surflon S-242" and "Surflon S-243" manufactured by AGC Seimi Chemical Co., Ltd., and perfluoroalkyl group-containing oligomers such as "Surflon S-386."

[0025] Among these, it is preferable that the nonionic surfactant (A) contains one or more selected from the group consisting of silicone surfactants and fluorine surfactants, because this allows the aqueous adhesive to be applied more uniformly to the aqueous ink image during production of the thermal transfer sheet and improves the washing fastness of the transferred image as a whole. The total proportion of the silicone surfactant and the fluorine surfactant in the nonionic surfactant (A) is preferably 0.5% by mass or more, more preferably 0.7% by mass or more, and particularly preferably 0.9% by mass or more, because this provides an excellent balance between the washing fastness of the transferred print and the image quality of the transferred image. Furthermore, it is preferably 5% by mass or less, more preferably 4% by mass or less, and particularly preferably 3.5% by mass or less.

[0026] The proportion of the silicone surfactant in the nonionic surfactant (A) is preferably 0.5% by mass or more, more preferably 0.7% by mass or more, and particularly preferably 0.9% by mass or more, because this provides an excellent balance between the washing fastness of the transfer print and the image quality of the transferred image, and is preferably 5% by mass or less, more preferably 4% by mass or less, and particularly preferably 3.5% by mass or less.

[0027] The proportion of the fluorine-based surfactant in the nonionic surfactant (A) is preferably 0.5% by mass or more, more preferably 0.7% by mass or more, and particularly preferably 0.9% by mass or more, because this provides an excellent balance between the washing fastness and the color development of the image in the transfer print. Also, it is preferably 3% by mass or less, more preferably 2% by mass or less, and particularly preferably 1.5% by mass or less.

[0028] The aqueous adhesive may contain a surfactant other than a nonionic surfactant as long as the effects of the invention are not impaired. The proportion of the nonionic surfactant (A) in the surfactants contained in the aqueous adhesive is preferably 60 mass% or more, more preferably 80 mass% or more, particularly preferably 90 mass% or more, and may even be 100 mass%.

[0029] The aqueous adhesive contains water. Examples of water include ion-exchanged water, distilled water, and ultrapure water. The water content of the aqueous adhesive is adjusted appropriately depending on the desired viscosity and the like, but may be, for example, in the range of 30 to 90 mass %.

[0030] The aqueous adhesive may contain other components in addition to water and the nonionic surfactant (A), such as resins, water-soluble organic solvents, colorants, pH adjusters, fixing agents, and preservatives.

[0031] When the aqueous adhesive contains a resin, the resin is preferably a water-dispersible resin. One type of water-dispersible resin may be used alone, or two or more types may be used in combination.

[0032] The type and physical properties of the water-dispersible resin are not particularly limited and are appropriately adjusted depending on the desired performance of the thermal transfer sheet. For example, to further enhance the washing fastness of a transfer-printed product, it is preferable to use a water-dispersible resin (B) (hereinafter sometimes referred to as "resin (B)") having a thermal melting temperature of 100°C or less, as this further enhances the anchoring effect on the fabric. The thermal melting temperature of resin (B) is more preferably 80°C or less, and particularly preferably 70°C or less. Furthermore, in order to achieve an excellent balance between the anchoring effect on the fabric and the image quality of the transferred image, the thermal melting temperature of resin (B) is preferably 30°C or more, more preferably 40°C or more, and particularly preferably 50°C or more. The thermal melting temperature of resin (B) may be in the range of 30 to 100°C.

[0033] 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.

[0034] Resin (B) is preferably one capable of forming a transparent coating film. 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; 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 excellent anchoring effect on fabrics.

[0035] 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.

[0036] The content of resin (B) in the aqueous adhesive is not particularly limited, but may be, for example, 5% by mass or more, 8% by mass or more, or 12% 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 aqueous adhesive may be in the range of 5 to 30% by mass.

[0037] The aqueous adhesive may contain a resin other than the resin (B). The proportion of the resin (B) in the resins contained in the aqueous adhesive is preferably 60% by mass or more, more preferably 80% by mass or more, particularly preferably 90% by mass or more, and may be 100% by mass.

[0038] The ratio of resin to nonionic surfactant (A) in the aqueous adhesive is arbitrary, but to achieve an excellent balance between washing fastness and image color development in the transfer print, the ratio of the nonionic surfactant (A) to the total mass of resin is preferably 8% by mass or more, more preferably 10% by mass or more, and particularly preferably 15% by mass or more. Also, the ratio is preferably 50% by mass or less, more preferably 35% by mass or less, and particularly preferably 25% by mass or less. The ratio of the nonionic surfactant (A) to the total mass of resin may be in the range of 8 to 50% by mass.

[0039] The aqueous adhesive may contain a water-soluble organic solvent. Any water-soluble organic solvent commonly used in the fields of aqueous adhesives or 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.

[0040] The content of the water-soluble organic solvent in the aqueous adhesive 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 aqueous adhesive may be in the range of 1 to 30% by mass.

[0041] The aqueous adhesive may contain a coloring material. One type of coloring material may be used alone, or two or more types may be used in combination. The type of coloring material is not particularly limited and is appropriately selected depending on the desired image on the thermal transfer sheet, etc. For example, when the printing target is a dark-colored cloth, the color of the cloth is concealed by the aqueous adhesive containing a white pigment, and a transfer image with excellent color reproducibility can be obtained.

[0042] Examples of white pigments include white inorganic pigments such as titanium oxide, zinc oxide, zinc sulfide, antimony oxide, and zirconium oxide. Among these, titanium oxide is preferred because it has excellent concealing properties for the color of the fabric to be transferred. The average particle size of titanium oxide is not particularly limited, but may be, for example, in the range of 100 to 600 nm.

[0043] The content of the coloring material in the aqueous adhesive is not particularly limited and can be in the same range as that of general aqueous inks. For example, when the coloring material is a white pigment, the content of the coloring material in the aqueous adhesive may be in the range of 1 to 30 mass %.

[0044] When the aqueous adhesive contains a colorant, it may contain a dispersant to stably disperse the colorant. The dispersant may be used alone or in combination of two or more. When the colorant is a pigment, various pigment dispersants can be used, and examples of the pigment dispersant include polymer dispersants and surfactant-type dispersants.

[0045] 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.

[0046] 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.).

[0047] When a pigment dispersant is used, the amount used is adjusted appropriately depending on the types of 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 pigment.

[0048] The method for producing the aqueous adhesive is not particularly limited, and it can be produced by the same method as general aqueous inks. Specifically, when the aqueous adhesive does not contain a colorant, it can be produced by blending and stirring the components contained in the aqueous adhesive. When the aqueous adhesive contains a colorant, it can be produced by a method in which an aqueous dispersion of the colorant is previously produced using a bead mill or the like, and this is blended with other components and stirred, or by a method in which all components of the aqueous adhesive are added to a mixer such as a three-one motor or mixed together and dispersed. After production of the aqueous adhesive, it may be passed through a filter such as a membrane filter, if necessary.

[0049] As will be described later, there are no particular limitations on the method for applying the aqueous adhesive in the production of thermal transfer sheets, but one preferred method is application by inkjet printing. In this case, from the viewpoint of inkjet ejection properties, the viscosity of the aqueous adhesive measured at 23°C may be in the range of 1 to 30 mPa s.

[0050] In one embodiment, the ink set includes aqueous inks. The ink set may include one or more aqueous inks depending on the desired transferred image. For example, if the aqueous adhesive does not include a colorant, the ink set may include one or more non-white inks and a white ink as the aqueous inks. If the aqueous adhesive includes a white pigment, the ink set may include one or more non-white inks as the aqueous inks, and the white portion of the image may be formed with the aqueous adhesive instead of the white aqueous ink. Furthermore, even if the aqueous adhesive includes a white pigment, the ink set may include one or more non-white inks and a white ink as the aqueous inks.

[0051] Non-white inks among aqueous inks contain non-white colorants. One type of colorant may be used alone, or two or more types may be used in combination. Examples of non-white pigments among non-white colorants include organic pigments such as azo pigments, phthalocyanine pigments, polycyclic pigments, and dye lake pigments, as well as 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.

[0052] As will be described later, the method for applying the aqueous ink in the production of the thermal transfer sheet is not particularly limited, but one preferred method is application by an inkjet system. In this case, from the viewpoint of the ejection stability and storage stability of the ink, the average particle size of the non-white 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.

[0053] The non-white pigment may be a self-dispersing pigment or a microencapsulated pigment in which the pigment is coated with a resin. 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.

[0054] Examples of self-dispersible non-white pigments include the "CAB-O-JET" series from 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 from Orient Chemical Industries Co., Ltd. ("BONJET BLACK CW-1," "BONJET BLACK CW-2," "BONJET BLACK CW-3," "BONJET BLACK CW-4," etc.).

[0055] 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.

[0056] 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 aqueous adhesive. Commercially available pigment dispersions in which a non-white pigment is pre-dispersed with a pigment dispersant include, for example, the HOSTAJET series manufactured by Clariant and the FUJI SP series manufactured by Fuji Pigment Co., Ltd.

[0057] For the white ink among the aqueous inks, the type of white pigment, particle size, amount of white pigment in the ink, type and amount of pigment dispersant used, etc. are the same as those for the aqueous adhesive containing a white pigment described above.

[0058] Water-based inks contain water. Examples of water include ion-exchanged water, distilled water, and ultrapure water. The water content of the water-based ink is adjusted appropriately depending on the desired viscosity and other factors, but may be, for example, in the range of 30 to 90% by mass.

[0059] The aqueous ink may contain, in addition to the colorant, water, and an optional pigment dispersant, other components such as a resin, a surfactant, a water-soluble organic solvent, a pH adjuster, a fixing agent, and a preservative.

[0060] When the aqueous ink contains a resin, the resin is preferably a water-dispersible resin. One type of water-dispersible resin may be used alone, or two or more types may be used in combination.

[0061] The type and physical properties of the water-dispersible resin are not particularly limited and are appropriately adjusted depending on the desired performance of the thermal transfer sheet. For example, in order to reduce the likelihood of miscibility between the aqueous ink image and the aqueous adhesive during transfer printing using the thermal transfer sheet and thereby obtain a higher-quality transfer image, it is preferable for the water-dispersible resin (C) (hereinafter sometimes referred to as "resin (C)") to be contained in the aqueous adhesive, having a thermal melting temperature equal to or higher than that of resin (B). The thermal melting temperature of resin (C) is preferably higher than that of resin (B), and the difference between the thermal melting temperature of resin (C) and that of resin (B) may be 50°C or higher, or may be 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 (C) and that of resin (B) may be in the range of 0 to 200°C.

[0062] Resin (C) is preferably one capable of forming a transparent coating film, since this results in an aqueous ink with superior color development. Specific examples of resin (C) 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; vinyl resins such as ethylene-vinyl acetate copolymer; functional group-modified resins obtained by modifying these various resins with monomers having functional groups such as carboxyl groups; 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 aqueous adhesives.

[0063] 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.).

[0064] The content of the resin (C) in the aqueous 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 the resin (C) in the aqueous ink may be in the range of 5 to 30% by mass.

[0065] The aqueous ink may contain a resin other than the resin (C). The proportion of the resin (C) in the resins contained in the aqueous ink is preferably 60% by mass or more, more preferably 80% by mass or more, and particularly preferably 90% by mass or more, and may be 100% by mass.

[0066] When the aqueous ink contains a surfactant, examples of the surfactant 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.

[0067] Specific examples of nonionic surfactants include those exemplified in the description of the aqueous adhesive. Of these, it is preferable that the aqueous ink contains a silicone surfactant, in order to obtain a transfer print with even better image quality. The content of the silicone surfactant in the aqueous 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 aqueous ink may be in the range of 0.05 to 10% by mass.

[0068] When the aqueous ink contains a water-soluble organic solvent, specific examples of the water-soluble organic solvent include those exemplified in the explanation of the aqueous adhesive. 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 aqueous 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 aqueous ink may be in the range of 1 to 35% by mass.

[0069] The method for producing the aqueous ink is not particularly limited, and the ink can be produced by the same method as that for general aqueous inks. For example, the ink can be produced by a method in which an aqueous dispersion of the colorant is produced in advance using a bead mill or the like, and this is mixed with other components and stirred, or by a method in which all components of the aqueous ink are added to a stirrer such as a three-one motor or in portions and dispersed. After production of the aqueous ink, the ink may be passed through a filter such as a membrane filter, if necessary.

[0070] When the aqueous ink is applied by the inkjet method, the viscosity of the aqueous ink may be in the range of 1 to 30 mPa·s as measured at 23° C., from the viewpoint of inkjet ejection properties.

[0071] In addition to the aqueous adhesive and the aqueous ink, the ink set of one embodiment may also include a pre-treatment liquid, a post-treatment liquid, etc. 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.

[0072] One embodiment of the thermal transfer sheet includes a substrate sheet, an aqueous ink image formed on the substrate sheet, and an aqueous adhesive application area. The aqueous adhesive contains a nonionic surfactant (A) and a resin, and the proportion of the nonionic surfactant (A) relative to the total mass of the resin is in the range of 8 to 50 mass%. In one embodiment of the thermal transfer sheet, the aqueous adhesive contains a nonionic surfactant (A), and the proportion of the nonionic surfactant (A) relative to the total mass of the resin is relatively high, in the range of 8 to 50 mass%, so that the aqueous adhesive application area has hot-melt properties and can adequately penetrate into the fabric during thermal transfer, thereby achieving an anchoring effect. Therefore, the thermal transfer sheet of one embodiment allows for the formation of a transfer image without any missing parts, even without a hot-melt powder layer, and produces a transfer print that also has excellent wash fastness.

[0073] In the thermal transfer sheet, the aqueous inks that form the aqueous ink images and the aqueous adhesives that form the aqueous adhesive-applied portions are as described above. That is, the aqueous ink images and aqueous adhesive-applied portions of the thermal transfer sheet can be formed using the ink set described above.

[0074] The thermal transfer sheet may have a hot melt powder layer, as with general thermal transfer sheets. The hot melt powder may be, for example, a hot melt powder commonly used for DTF printing. On the other hand, as mentioned above, the thermal transfer sheet does not need to have a hot melt powder layer because the aqueous adhesive application 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.

[0075] 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 an aqueous ink onto a substrate sheet and then applying an aqueous adhesive by a wet-on-wet method, wherein the aqueous adhesive contains a nonionic surfactant (A) and the content of the nonionic surfactant (A) in the aqueous adhesive is in the range of 1.5 to 10 mass %.

[0076] In the method for producing a thermal transfer sheet, the water-based ink and water-based adhesive are as described above. That is, the thermal transfer sheet can be produced using the ink set described above.

[0077] 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.

[0078] The substrate sheet may have a primer layer containing a cationic resin, since this provides excellent color development and a high-quality transfer image. 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.

[0079] 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.

[0080] 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.

[0081] The method for applying the aqueous ink to 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 easy control of the amount 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.

[0082] The amount of water-based ink applied can be adjusted appropriately depending on the type of substrate sheet, the design of the transferred image, etc., but is, for example, 5 to 50 g / m 2 When multiple types of water-based inks are used, the amount of each may be in the range of 5 to 50 g / m 2 may be in the range of

[0083] After the application of the aqueous ink, the aqueous adhesive is applied by a wet-on-wet method. In the wet-on-wet method, the aqueous adhesive is applied without any special drying process after the application of the aqueous ink. The method for applying the aqueous adhesive is not particularly limited, and it can be applied by the same method as for the aqueous ink. The amount of the aqueous adhesive applied can be adjusted appropriately depending on the type of substrate sheet, the design of the transferred image, etc., but for example, 50 g / m 2 ~300g / m 2 may be in the range of

[0084] In the method for producing a thermal transfer sheet, in addition to the aqueous ink and aqueous adhesive, other materials may be used. Examples of other materials include a pretreatment liquid applied to the substrate sheet before applying the aqueous ink, a posttreatment liquid applied after applying the aqueous adhesive, 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.

[0085] The method for producing a thermal transfer sheet may include a drying step. The drying step may be performed after applying the aqueous adhesive. Furthermore, when a post-treatment liquid is used, the drying step may be performed after applying the post-treatment liquid. The drying temperature and drying time are optional, but may be, for example, drying in the range of 50 to 150°C for about 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 aqueous ink and aqueous adhesive may be removed.

[0086] 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.

[0087] 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.

[0088] The transfer conditions, such as pressure, temperature, and pressing time, are adjusted appropriately depending on the type of fabric. For example, when using a heat press machine "Hotronix Fusion Heat Press" manufactured by Stahls Photoronix, the pressure conditions may be in the range of 3 to 12 pr, the temperature conditions may be in the range of 90 to 160°C, and the pressing time may be in the range of 5 to 30 seconds. As mentioned above, the thermal transfer sheet of one embodiment can produce a transfer print with excellent washing fastness even at a low transfer temperature of about 120°C.

[0089] After the image is transferred, it is preferable to cool the transfer print to room temperature before peeling off the substrate sheet.

[0090] Some embodiments of the present disclosure are set forth below. <1> An ink set for a thermal transfer sheet, comprising an aqueous ink and an aqueous adhesive, wherein the aqueous adhesive contains a nonionic surfactant (A), and the content of the nonionic surfactant (A) in the aqueous adhesive is in the range of 1.5 to 10 mass %.

[0091] <2> The content of the nonionic surfactant (A) in the aqueous adhesive is in the range of 2.5 to 5 mass %. <1> An ink set for a thermal transfer sheet according to the present invention.

[0092] <3> The nonionic surfactant (A) comprises one or more surfactants selected from the group consisting of silicone surfactants and fluorine surfactants. <1> or <2> 10. An ink set for a thermal transfer sheet according to claim 19.

[0093] <4> The aqueous adhesive contains a water-dispersible resin (B) having a thermal melting temperature of 100°C or less. <1> ~ <3> 1. An ink set for a thermal transfer sheet according to any one of the preceding items.

[0094] <5> the aqueous ink contains a water-dispersible resin (C), and the thermal melting temperature of the water-dispersible resin (C) is higher than the thermal melting temperature of the water-dispersible resin (B); <1> ~ <4> 1. An ink set for a thermal transfer sheet according to any one of the preceding items.

[0095] <6> A thermal transfer sheet having a substrate sheet, and an aqueous ink image and an aqueous adhesive application portion formed on the substrate sheet, the aqueous adhesive containing a nonionic surfactant (A) and a resin, and the proportion of the nonionic surfactant (A) to the total mass of the resin is in the range of 8 to 50 mass%.

[0096] <7> The above-mentioned hot melt powder-free <6> The thermal transfer sheet according to claim 1.

[0097] <8> A method for producing a thermal transfer sheet, comprising applying an aqueous ink onto a base sheet and then applying an aqueous adhesive by a wet-on-wet method, wherein the aqueous adhesive contains a nonionic surfactant (A), and the content of the nonionic surfactant (A) in the aqueous adhesive is in the range of 1.5 to 10 mass %.

[0098] <9> The above-mentioned hot melt powder-free <8> A method for producing the thermal transfer sheet according to claim 1.

[0099] <10> 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]

[0100] 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.

[0101] 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.

[0102] [Manufacturing ink sets for thermal transfer sheets] Water-based adhesives (1) to (10) and (1') to (3') and water-based inks (1) and (2) were produced in the following manner, and these were combined to form an ink set for thermal transfer sheets.

[0103] [Production of water-based adhesives] The raw materials were mixed in the compounding ratios shown in Table 1 and filtered through a cellulose acetate membrane filter with a pore size of 3 μm to obtain water-based adhesives (1) to (10) and (1′) to (3′).

[0104] [Table 1]

[0105] The details of the raw materials listed in Table 1 are as follows: Nonionic surfactant (A-1): Silicone surfactant, "Silface SAG503A" by Nissin Chemical Industry Co., Ltd., HLB value 11, active ingredient 100% by mass Nonionic surfactant (A-2): Fluorine-based surfactant, AGC Seimi Chemical Co., Ltd.'s "Surflon S-243," active ingredient 100% by mass Nonionic surfactant (A-3): Acetylene glycol surfactant, "Surfynol 465" by Nissin Chemical Industry Co., Ltd., HLB value 13, active ingredient 100% by mass Nonionic surfactant (A-4): Polyoxyethylene alkyl ether (secondary alkyl ether with 12 to 14 repeating oxyethylene chains), "NIKKOL BT-12" from Nikko Chemicals Co., Ltd., HLB value 14.5, active ingredient 100% by mass Nonionic surfactant (A-5): Polyoxyethylene oleyl ether (oxyethylene chain repeat number: 20), "NIKKOL BO-20V" from Nikko Chemicals Co., Ltd., HLB value: 17, active ingredient: 100% by mass Nonionic surfactant (A-6): Polyoxyethylene sorbitan fatty acid ester (sorbitan monolaurate ethylene oxide addition polymer, oxyethylene chain repeat number 20), "NIKKOL TL-10" from Nikko Chemicals Co., Ltd., HLB value 17, active ingredient 100% by mass Nonionic surfactant (A-7): Polyglycerin fatty acid ester (hexaglyceryl monolaurate), "NIKKOL HEXAGLYN 1-L" from Nikko Chemicals Co., Ltd., HLB value 14.5, active ingredient 100% by mass Anionic surfactant: Special polycarboxylic acid type polymer surfactant, Kao Corporation's "Demol EP", active ingredient 25% by mass 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 (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 Water-soluble organic solvent: Diethylene glycol from Fujifilm Wako Pure Chemical Industries, Ltd.

[0106] [Water-based 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 non-white inks (1) and (2).

[0107] [Table 2]

[0108] Details of the raw materials listed in Table 2 are as follows: Magenta pigment dispersion: Cabot "CAB-O-JET 260M", pigment content 10% by weight Water-dispersible resin (C-1): Daiichi Kogyo Seiyaku Co., Ltd. "Superflex 420", a urethane resin water dispersion with a thermal melting temperature of 205°C, resin content 32% by mass Water-dispersible resin (C-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 Water-soluble organic solvent: Diethylene glycol from Fujifilm Wako Pure Chemical Industries, Ltd.

[0109] [Thermal transfer sheet manufacturing] The aqueous ink and the aqueous adhesive were applied in this order by the wet-on-wet method onto a substrate sheet (a DTF print film manufactured by Toyo Corporation). The application of the aqueous ink and the aqueous adhesive was carried out by inkjet printing using an inkjet printer "MMP-8130" manufactured by Mastermind. The aqueous ink was ejected at a rate of 25 g / m. 2 A 10cm x 20cm solid image was printed. The water-based adhesive was used at a discharge rate of 100g / m 2 A 10 cm x 20 cm solid image was printed on top of the aqueous ink application area. The sheet was then dried for 5 minutes in an ESPEC thermostatic chamber set at 110°C to obtain a thermal transfer sheet. The types of aqueous ink and aqueous adhesive used in each example are shown in Table 3.

[0110] [Production and evaluation of transfer prints] The printed side of the thermal transfer sheet obtained above was placed on a white cotton T-shirt or a black cotton T-shirt manufactured by Tom's Co., Ltd., and heat-pressed using a Stahls Photoronix "Hotronix Fusion Heat Press" at a pressure setting of 7 psi, 120°C, and 20 seconds. After cooling to room temperature, the base sheet was peeled off to obtain a transfer print. The transfer print was then subjected to the following evaluation tests. The results are shown in Table 3.

[0111] [Evaluation of washing fastness] The transfer print was washed according to the AATCC 61 2a standard and then evaluated according to the following criteria. S: Washing fastness level 4.5 or higher A: Washing fastness level 3.5 to 4 B: Washing fastness level 2.5 to 3.0 C: Washing fastness level 2.0 or less

[0112] [Evaluation of image quality of transferred image] The image quality of the transfer print was visually observed and evaluated according to the following criteria. A: High color development and high color reproducibility of transferred images B: Color development is somewhat high, and a decrease in color reproducibility is observed only in a part of the transferred image. C: Poor color development and poor overall image quality

[0113] [Table 3]

[0114] In Examples 1 to 11, which used aqueous adhesives (1) to (10) containing 1.5 to 10% by mass of nonionic surfactant (A), transfer prints with excellent washing fastness were obtained. On the other hand, in Comparative Examples 1 to 3, in which the content of nonionic surfactant (A) was less than 1.5% by mass, the transfer prints had poor washing fastness. Comparative Example 2 contained a large amount of anionic surfactant, but this was not effective in improving washing fastness.

Claims

1. An ink set for a thermal transfer sheet, comprising a water-based ink and a water-based adhesive, The aqueous adhesive contains a nonionic surfactant (A), The ink set for a thermal transfer sheet, wherein the content of the nonionic surfactant (A) in the aqueous adhesive is in the range of 1.5 to 10 mass %.

2. 2. The ink set for thermal transfer sheets according to claim 1, wherein the content of the nonionic surfactant (A) in the aqueous adhesive is in the range of 2.5 to 5% by mass.

3. 2. The ink set for thermal transfer sheets according to claim 1, wherein the nonionic surfactant (A) comprises at least one selected from the group consisting of silicone-based surfactants and fluorine-based surfactants.

4. 2. The ink set for thermal transfer sheets according to claim 1, wherein the aqueous adhesive contains a water-dispersible resin (B) having a thermal melting temperature of 100°C or less.

5. 5. The ink set for thermal transfer sheets according to claim 1, wherein the aqueous ink contains a water-dispersible resin (C), and the heat melting temperature of the water-dispersible resin (C) is higher than the heat melting temperature of the water-dispersible resin (B).

6. a substrate sheet and a water-based ink image and a water-based adhesive application portion formed on the substrate sheet; the aqueous adhesive comprises a nonionic surfactant (A) and a water-dispersible resin (B), A thermal transfer sheet, wherein the ratio of the nonionic surfactant (A) to the resin solid content of the water-dispersible resin (B) is in the range of 8 to 50 mass %.

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 an aqueous ink onto a substrate sheet, and then applying an aqueous adhesive to the substrate by a wet-on-wet method, The aqueous adhesive contains a nonionic surfactant (A), The method for producing a thermal transfer sheet, wherein the content of the nonionic surfactant (A) in the aqueous adhesive is in the range of 1.5 to 10 mass %.

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

10. 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