Inkjet ink composition for dye printing

Abstract

An inkjet ink composition for dye printing, which has a higher level and excellent storage stability and discharge stability, is obtained. The inkjet ink composition for dye printing according to the present invention comprises a disperse dye, a dispersant, a water-soluble organic solvent, and a permeability-imparting solvent, the water-soluble organic solvent comprising glycerol and propylene glycol, and the permeability-imparting solvent comprising a solvent selected from the group consisting of 1, 5-pentanediol, 1, 2-butanediol, 3-methyl-1, 3-pentanediol, 1, 2-butanediol, 3-methyl-1, 3-pentanediol, 1, 3-pentanediol, 1, 3-pentanediol, and one or more compounds selected from the group consisting of 1, 5-pentanediol and methoxypolyethylene glycol.

Description

Technical Field

[0001] The present invention relates to an inkjet ink composition for dye printing. Background Art

[0002] Inkjet recording methods are not only used to record images on media such as paper, but are also being explored for textile printing. Various ink compositions and recording methods have been studied for inkjet printing. For example, Patent Document 1 discloses an aqueous inkjet composition comprising a sublimation dye, a dye consisting of at least one disperse dye, a polyester, 1-(hydroxyalkyl)-2-pyrrolidone, and water. The polyester content is 4.0 to 300 times the dye content.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2021-155476

[0004] However, the aqueous inkjet ink composition described in Patent Document 1 has the problem that a higher level of storage stability and discharge stability cannot be achieved. Summary of the Invention

[0005] The present invention relates to an inkjet ink composition for dye printing, comprising a disperse dye, a dispersant, a water-soluble organic solvent, a penetrating solvent, and water, wherein the water-soluble organic solvent comprises glycerol and propylene glycol, and the penetrating solvent comprises one or more selected from the group consisting of 1,5-pentanediol, 1,2-butanediol, 3-methyl-1,5-pentanediol, and polyethylene glycol monomethyl ether. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 This is a flowchart showing an example of an inkjet recording method.

[0007] Figure 2 Table 1 shows the composition of the ink composition for dye solubility evaluation.

[0008] Figure 3 Table 2 shows the composition of the inkjet ink composition for dye printing.

[0009] Figure 4 Table 3 shows the composition of the inkjet ink composition for dye printing.

[0010] Figure 5 Table 4 shows the composition of the inkjet ink composition for dye printing.

[0011] Figure 6 Table 5 shows the evaluation results.

[0012] Figure 7 Table 6 shows the evaluation results.

[0013] Figure 8 Table 7 shows the evaluation results. DETAILED DESCRIPTION

[0014] Hereinafter, an embodiment of the present invention (hereinafter referred to as “this embodiment”) will be described in detail, but the present invention is not limited thereto and various modifications are possible without departing from the gist of the invention.

[0015] 1. Inkjet ink composition for dye printing

[0016] The inkjet ink composition for dye printing (hereinafter also referred to as "ink composition") of this embodiment contains a disperse dye, a dispersant, a water-soluble organic solvent, a penetrating solvent and water, the water-soluble organic solvent contains glycerol and propylene glycol, and the penetrating solvent contains one or more selected from the group consisting of 1,5-pentanediol, 1,2-butanediol, 3-methyl-1,5-pentanediol and polyethylene glycol monomethyl ether.

[0017] According to this embodiment, an ink composition having higher levels of excellent storage stability and discharge stability can be obtained.

[0018] Although the main reason why such excellent effects are obtained by this embodiment cannot be determined, the present inventors presume the following.

[0019] Conventional water-soluble inkjet ink compositions for dye printing, which contain disperse dyes, dispersants, and water, also contain water-soluble organic solvents. However, depending on the water-soluble organic solvent, the disperse dyes and dispersants cannot be properly dissolved in water, making it difficult to obtain an ink composition with excellent storage stability and ejection stability.

[0020] However, in the water-soluble dye printing inkjet ink composition of the present embodiment, a specific water-soluble organic solvent and a specific penetrating solvent are also included together with the disperse dye, dispersant, and water. The specific penetrating solvent has a relatively high affinity for the disperse dye and the dispersant. Moreover, the specific penetrating solvent also has a relatively high affinity for the specific water-soluble organic solvent. On this basis, the specific penetrating solvent has a relatively high affinity for the specific water-soluble organic solvent, but the specific water-soluble organic solvent also has a higher hydrophilicity among water-soluble organic solvents. By including such a specific water-soluble organic solvent and a specific penetrating solvent in the ink composition, the disperse dye and the dispersant can be more appropriately dissolved in water. Therefore, according to the present embodiment, it is inferred that an ink composition with a higher level of excellent storage stability and ejection stability can be obtained. However, the reason is not limited to this.

[0021] Next, each component contained in the ink composition will be described.

[0022] 1.1. Disperse dyes

[0023] The ink composition includes a disperse dye.

[0024] Disperse dyes are usually formed into particles and are color materials dispersed in a dispersion medium by a dispersant. In addition, disperse dyes are usually nonionic dyes having a hydrophilic group and an appropriate polar group. Disperse dyes can be used alone or in combination of two or more.

[0025] Examples of the disperse dye include CI disperse yellow, CI disperse red, CI disperse blue, CI disperse orange, CI disperse violet, CI disperse green, CI disperse brown, and CI disperse black.

[0026] As the disperse dye, a sublimation dye is preferred. In this specification, a "sublimation dye" refers to a dye having a property of sublimating by heating.

[0027] Specific examples of the sublimation disperse dyes include CI Disperse Yellow 3, 7, 8, 23, 39, 51, 54, 60, 71, and 86; CI Disperse Orange 1, 1:1, 5, 20, 25, 25:1, 33, 56, and 76; CI Disperse Brown 2; and CI Disperse Red 11, 50, 53, 55, 55:1, 59, 60, 65, 70, 75, 93, 146, 158, 190, and 190: 1, 207, 239 and 240; CI Vat Red 41; CI Disperse Violet 8, 17, 23, 27, 28, 29, 36 and 57; CI Disperse Blue 14, 19, 26, 26: 1, 35, 55, 56, 58, 64, 64: 1, 72, 72: 1, 81, 81: 1, 91, 95, 108, 131, 141, 145 and 359; CI Solvent Blue 36, 63, 105 and 111.

[0028] The disperse dye preferably contains one or more selected from the group consisting of CI Disperse Yellow, CI Disperse Red, CI Disperse Blue, and CI Disperse Orange. It is more preferred that the disperse dye contain one or more selected from the group consisting of CI Disperse Yellow 54, CI Disperse Red 60, CI Disperse Blue 359, and CI Disperse Orange 25. It is even more preferred that the disperse dye contain one or more selected from the group consisting of CI Disperse Red 60 and CI Disperse Orange 25. When the disperse dye contains the above-mentioned disperse dyes, an ink composition having a higher level of excellent storage stability and ejection stability tends to be obtained.

[0029] The disperse dye content is preferably 5.0% by mass or greater, more preferably 5.1% by mass or greater and 20.0% by mass or less, further preferably 5.2% by mass or greater and 15.0% by mass or less, and even more preferably 5.3% by mass or greater and 10.0% by mass or less, relative to the total amount of the ink composition. When the disperse dye content is within this range, an ink composition having a higher level of excellent storage stability and ejection stability tends to be obtained.

[0030] 1.2. Dispersants

[0031] The ink composition contains a dispersant, which may be used alone or in combination of two or more.

[0032] Dispersants have the function of stably dispersing disperse dyes in ink. Examples of dispersants include anionic dispersants, nonionic dispersants, and polymer dispersants. Among these, anionic dispersants are preferred due to their superior dispersion stability in the inkjet ink composition.

[0033] Preferred anionic dispersants are salts of formaldehyde condensates of aromatic sulfonic acids. Examples of "aromatic sulfonic acids" in the salts of formaldehyde condensates of aromatic sulfonic acids include naphthalenesulfonic acid, creosotesulfonic acid, cresolsulfonic acid, phenolsulfonic acid, alkylnaphthalenesulfonic acids such as β-naphtholsulfonic acid, methylnaphthalenesulfonic acid, and butylnaphthalenesulfonic acid, mixtures of β-naphthalenesulfonic acid and β-naphtholsulfonic acid, mixtures of cresolsulfonic acid and 2-naphthol-6-sulfonic acid, and ligninsulfonic acid. Examples of "salts" include sodium salts.

[0034] Furthermore, the anionic dispersant preferably contains at least one selected from the group consisting of sodium salts of naphthalenesulfonic acid formaldehyde condensates and sodium salts of ligninsulfonic acid, and more preferably contains sodium salts of naphthalenesulfonic acid formaldehyde condensates. These anionic dispersants have a greater effect on improving the dispersion stability of disperse dyes, and tend to provide an ink composition with even higher and superior storage stability and ejection stability.

[0035] Examples of the nonionic dispersant include ethylene oxide adducts of phytosterol and ethylene oxide adducts of cholesterol.

[0036] Examples of the polymer dispersant include partial alkyl polyacrylates, polyalkylene polyamines, polyacrylates, styrene-acrylic acid copolymers, and vinylnaphthalene-maleic acid copolymers.

[0037] The content of the dispersant is preferably 0.1% by mass to 30.0% by mass, more preferably 1.0% by mass to 20.0% by mass, and even more preferably 5.0% by mass to 10.0% by mass, relative to 100% by mass of the ink. This tends to facilitate adjustment of the ink viscosity to a viscosity more suitable for inkjet printing.

[0038] 1.3. Water-soluble organic solvents

[0039] The ink composition includes a water-soluble organic solvent, which includes glycerin and propylene glycol.

[0040] By using glycerol and propylene glycol as the water-soluble organic solvent, the disperse dye and the dispersant can be more appropriately dissolved in water, thereby obtaining an ink composition having a higher level of excellent storage stability and discharge stability.

[0041] Glycerin and propylene glycol also function as excellent moisturizers.

[0042] The total content of glycerol and propylene glycol, which serve as water-soluble organic solvents, is preferably from 11.0% to 30.0% by mass, and more preferably from 16.0% to 24.0% by mass, relative to the total amount of the ink composition. When the total content is within this range, an ink composition with even higher and superior storage stability and ejection stability tends to be obtained.

[0043] The glycerol content is preferably from 10.0% to 20.0% by mass, and more preferably from 13.0% to 17.0% by mass, relative to the total amount of the ink composition. When the glycerol content is within this range, an ink composition having even higher and superior storage stability and ejection stability tends to be obtained.

[0044] The propylene glycol content is preferably from 1.0% to 10.0% by mass, and more preferably from 3.0% to 7.0% by mass, relative to the total amount of the ink composition. When the propylene glycol content is within this range, an ink composition having even higher and superior storage stability and ejection stability tends to be obtained.

[0045] 1.4. Penetrating solvent

[0046] The ink composition includes a penetrating solvent. The penetrating solvent includes one or more selected from the group consisting of 1,5-pentanediol, 1,2-butanediol, 3-methyl-1,5-pentanediol, and polyethylene glycol monomethyl ether.

[0047] The specific penetrating solvent described above has a relatively high affinity for disperse dyes and dispersants. Therefore, the use of the specific penetrating solvent allows for more appropriate dispersion of the disperse dyes and dispersants. Consequently, an ink composition exhibiting higher and superior storage stability and ejection stability can be obtained. The penetrating solvents may be used alone or in combination of two or more.

[0048] Polyethylene glycol monomethyl ether is preferably included as the penetrating solvent. Polyethylene glycol monomethyl ether has a greater effect of improving the dispersion stability of the disperse dye, and tends to provide an ink composition with higher and more excellent storage stability and ejection stability.

[0049] The content of the penetrating solvent is preferably from 0.5% to 10.0% by mass, and more preferably from 1.0% to 5.0% by mass, relative to the total amount of the ink composition. When the content of the penetrating solvent is within this range, an ink composition having even higher and superior storage stability and ejection stability tends to be obtained.

[0050] 1.5. Water

[0051] The ink composition includes water.

[0052] Examples of water include pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, as well as water from which ionic impurities have been removed as much as possible, such as ultrapure water. Furthermore, when storing the ink composition for a long period of time, water sterilized by ultraviolet irradiation, addition of hydrogen peroxide, or the like is preferred because it can inhibit the growth of mold and bacteria.

[0053] The water content is preferably 30.0% by mass or more and 80.0% by mass or less relative to the total amount of the ink composition. By setting the water content within the above range, an increase in the viscosity of the ink composition can be suppressed.

[0054] 1.6. Surfactants

[0055] The ink composition may also contain a surfactant.

[0056] Surfactants reduce the surface tension of the ink composition, thereby adjusting its wettability with the recording medium. Examples of surfactants include acetylene glycol surfactants and silicone surfactants. Surfactants may be used alone or in combination of two or more.

[0057] Examples of acetylene glycol surfactants include Surfynol (registered trademark) 104, 104E, 104H, 104A, 104BC, 104DPM, 104PA, 104PG-50, 104S, 420, 440, 465, 485, SE, SE-F, 504, 61, DF37, CT111, CT121, CT131, CT136, TG, GA, and DF110D (manufactured by Nissin Chemical Industry Co., Ltd.); OLFINE (registered trademark); (Registered trademark) B, Y, P, A, STG, SPC, E1004, E1010, PD-001, PD-002W, PD-003, PD-004, EXP.4001, EXP.4036, EXP.4051, AF-103, AF-104, AK-02, SK-14; AE-3 (manufactured by Nissin Chemical Industry Co., Ltd.); Acetylenol (registered trademark) E00, E00P, E40, E100 (manufactured by Kawaken Fine Chemicals Co., Ltd.).

[0058] Examples of the silicone surfactant include polysiloxane compounds such as polyether-modified organosiloxane. Examples of commercially available polyether-modified organosiloxanes include BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, and BYK-348 (manufactured by BYK Chemical Japan Co., Ltd.), and KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, KF-6004, KF-6020, X-22-4515, KF-6011, KF-6012, KF-6015, and KF-6017 (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0059] The surfactant preferably includes a silicone surfactant, and more preferably includes a polysiloxane compound. If the ink composition includes the above-mentioned surfactant, it tends to be possible to obtain an ink composition having further high and excellent storage stability and ejection stability.

[0060] The surfactant content is preferably 0.01% to 10.0% by mass, more preferably 0.05% to 5.0% by mass, and even more preferably 0.1% to 1.0% by mass, relative to the total amount of the ink composition. When the surfactant content is within this range, an ink composition having even higher and superior storage stability and ejection stability tends to be obtained.

[0061] pH adjusters

[0062] The ink composition may also contain a pH adjuster.

[0063] If the ink composition contains a pH adjuster, an ink composition having further improved and excellent storage stability and discharge stability tends to be obtained. The pH adjuster may be used alone or in combination of two or more.

[0064] Examples of pH adjusters include acids, bases, and appropriate combinations of weak acids and weak bases. Examples of acids and bases used in such combinations include inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid; inorganic bases such as lithium hydroxide, sodium hydroxide, potassium hydroxide, potassium dihydrogen phosphate, disodium hydrogen phosphate, potassium carbonate, sodium carbonate, sodium bicarbonate, and ammonia; organic bases such as triethylamine, trimethylamine, diethylethanolamine, triethanolamine, diethanolamine, monoethanolamine, tripropanolamine, triisopropanolamine, diisopropanolamine, and tris(hydroxymethyl)aminomethane (THAM); and adipic acid, citric acid, succinic acid, lactic acid, N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid (BES), 4-(2-hydroxyethyl)-1-piperidin. Organic acids such as HEPES, MES, MOPS, ADA, PIPES, N-(2-acetamido)-2-aminoethanesulfonic acid (ACES), 2-hydroxyethylamine hydrochloride, TES, acetamidoglycine, tris(hydroxymethyl)glycine, glycineamide, and bis(hydroxyethyl)glycine, as well as Good's buffers, phosphate buffers, citrate buffers, and Tris buffers can also be included as part or all of the pH adjuster to achieve a more stable pH buffering effect. Tertiary amines such as triethanolamine and triisopropanolamine, and carboxyl-containing organic acids such as adipic acid, citric acid, succinic acid, and lactic acid can also be included as part or all of the pH adjuster. In addition, sodium acetate, ammonium acetate, sodium formate, ammonium formate, sodium carbonate, sodium bicarbonate, potassium bicarbonate, monosodium phosphate, monopotassium phosphate, disodium phosphate, and trisodium phosphate having a buffering effect may be used together with the pH adjuster.

[0065] The pH adjuster preferably contains triethanolamine. If the ink composition contains the pH adjuster described above, an ink composition having further high and excellent storage stability and ejection stability tends to be obtained.

[0066] The pH adjuster content is preferably from 0.05% to 5.0% by mass, and more preferably from 0.1% to 3.0% by mass, relative to the total amount of the ink composition. When the pH adjuster content is within this range, an ink composition having even higher and superior storage stability and ejection stability tends to be obtained.

[0067] 1.8. Other ingredients

[0068] In addition to the aforementioned components, the ink composition may also contain various additives commonly used in ink compositions, such as a solubilizing agent, a viscosity modifier, an antioxidant, a UV absorber, an oxygen absorber, a preservative, a mildew inhibitor, a corrosion inhibitor, and a chelating agent for trapping metal ions that affect dispersion. These additives may be used alone or in combination of two or more.

[0069] Examples of the preservative include sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, and 1,2-dibenzisothiazol-3-one.

[0070] Commercially available preservatives can also be used. Examples of commercially available preservatives include CRL, BND, GXL, XL-2, and TN (trade names) from the Proxel (registered trademark) series manufactured by Lonza Japan. Preservatives may be used alone or in combination of two or more.

[0071] The content of each additive can be 0.01% by mass or more and 5.0% by mass or less relative to the total amount of the ink composition.

[0072] 1.9. Physical Properties of Ink Composition

[0073] 1.9.1. Viscosity

[0074] The viscosity of the ink composition is preferably 1.5 mPa·s to 10.0 mPa·s, and more preferably 2.0 mPa·s to 78.0 mPa·s at 20°C. When the viscosity of the ink composition is within this range, an ink composition having even higher and superior storage stability and ejection stability tends to be obtained.

[0075] The viscosity of the ink composition can be measured using a viscoelasticity measuring device (Anton Paar Japan Co., Ltd., viscoelasticity tester MCR-300). Specifically, the viscosity can be measured by adjusting the temperature of the ink composition to 20°C and reading the shear rate for 200 seconds. -1 The shear viscosity (mPa·s) under 0.05°C was measured.

[0076] 1.9.2. Surface tension

[0077] The surface tension of the ink composition at 25°C is preferably 10 mN / m to 40 mN / m, and more preferably 22 mN / m to 35 mN / m. When the surface tension of the ink composition is within this range, the ink composition tends to have higher and superior storage stability and ejection stability.

[0078] The surface tension of the ink composition can be measured using a surface tensiometer CBVP-Z (trade name, manufactured by Kyowa Interface Science Co., Ltd.) as the surface tension when a platinum plate is wetted with the ink composition at room temperature and pressure.

[0079] 1.9.3.pH

[0080] The pH of the ink composition is preferably 7.0 or higher and 9.5 or lower at 25° C. When the pH of the ink composition is within the above range, an ink composition having further high and excellent storage stability and discharge stability tends to be obtained.

[0081] The pH of the ink composition can be measured using, for example, a benchtop pH meter by immersing an electrode portion in the ink composition.

[0082] 1.9.4. Particle size

[0083] The particle size of the ink composition is the average particle size. In this specification, the particle size refers to the particle size at which the frequency reaches 50%, calculated cumulatively from the smallest particle size side, in a particle distribution measured by dynamic light scattering. This can be determined, for example, by measurement using a particle size distribution analyzer, Nanotrac Wave-EX (manufactured by Nikkiso).

[0084] The particle size of the ink composition at 25° C. is preferably 80 nm to 200 nm, and more preferably 100 nm to 170 nm.

[0085] A change in the particle size of the disperse dye dispersed in the dispersion medium by the dispersant, particularly an increase in the particle size, means a decrease in dispersion stability. In an inkjet composition with reduced dispersion stability, ejection stability is reduced.

[0086] 1.10. Method for producing ink composition

[0087] The ink composition can be prepared by mixing a disperse dye, a dispersant, a water-soluble organic solvent, a penetrating solvent, water, and, if necessary, a surfactant, a pH adjuster, and other ingredients in any order, and then filtering or other methods as needed to remove impurities and foreign matter. The components are mixed by sequentially adding the ingredients to a container equipped with a stirring device such as a mechanical stirrer or a magnetic stirrer, stirring and mixing them. Examples of filtration methods include centrifugal filtration and filtration.

[0088] Alternatively, the disperse dye, dispersant, and water may be mixed in any order beforehand, and after obtaining a dye dispersion dispersed using a paint shaker or the like, the ink composition may be prepared using this dye dispersion, a water-soluble organic solvent, and a penetrating solvent. This allows for better dispersion of the disperse dye in the ink composition.

[0089] 2. Inkjet recording method

[0090] The recording method of this embodiment may also include at least: an ink adhesion step, in which the ink is ejected from the recording head and adheres to the transfer paper; and a transfer step, in which the dye contained in the ink is sublimated and transferred from the transfer paper to the recording medium. In addition, the recording method of this embodiment may also include other steps according to other needs. In addition, Figure 1 An example of the inkjet recording method of this embodiment is shown. This inkjet recording method includes an ink attaching step and a heating step in sequence. Next, a recording medium, an inkjet recording apparatus that can be used in the recording method, and each step are described.

[0091] As a recording method utilizing such sublimation transfer, there is, for example, a method in which a transfer image is formed by inkjet printing on a sheet-like intermediate transfer medium such as transfer paper, the intermediate transfer medium is overlapped with a recording medium such as cloth (transfer target medium), and the obtained transfer image is sublimated and transferred by heating.

[0092] 2.1. Ink adhesion process

[0093] In this process, ink is ejected from a recording head using an inkjet method, and the ink is deposited on a recording surface of transfer paper serving as an intermediate transfer medium to form a transferred image. Ink ejection using the inkjet method can be performed using a droplet ejection device such as an inkjet recording device.

[0094] Inkjet recording devices are not particularly limited, as long as they have at least an ink container, such as a cartridge or tank, and a recording head connected thereto, and are capable of ejecting ink from the recording head to form an image on transfer paper, which serves as an intermediate transfer medium. Both serial and line-type inkjet recording devices are also available. These types of inkjet recording devices are equipped with a recording head that intermittently ejects droplets of ink at a predetermined volume from the recording head's nozzles at predetermined timings while changing the relative position of the transfer paper and the recording head. This allows the ink to adhere to the transfer paper, forming a predetermined transfer image.

[0095] Typically, in serial inkjet recording devices, the transfer paper's transport direction intersects the reciprocating motion of the recording head. The combination of the reciprocating motion of the recording head and the transfer paper's transport causes the relative positional relationship between the transfer paper and the recording head to change. In this case, the recording head typically has multiple nozzle holes arranged in a row, or "nozzle array," along the transfer paper's transport direction. Depending on the type and quantity of the first to fourth inks, multiple nozzle arrays may also be formed in the recording head.

[0096] Furthermore, in line-type inkjet recording devices, the recording head typically does not reciprocate, and the relative position between the transfer paper and the recording head changes as the transfer paper is transported. In this case, the recording head is typically provided with multiple nozzle holes, with nozzle arrays formed in a direction intersecting the direction of transfer paper transport.

[0097] The inkjet recording method is not particularly limited as long as it can eject ink as droplets from tiny nozzle holes and deposit these droplets on the transfer paper. For example, a piezoelectric method or a method that ejects ink by heating the ink to generate bubbles can be used. In this embodiment, the piezoelectric method is preferably used because it is less likely to deteriorate the ink.

[0098] The inkjet recording apparatus can employ a known configuration such as a heating unit, a drying unit, a roller unit, and a winding device.

[0099] In this embodiment, the transfer paper serving as the intermediate transfer medium can be any recording medium provided with an ink-receiving layer, such as plain paper, inkjet paper, or coated paper. However, paper provided with an ink-receiving layer made of inorganic particles such as silicon dioxide is preferred. This allows for the production of an intermediate recording material with minimal bleeding from the recording surface during the drying process of the ink applied to the intermediate transfer medium. Furthermore, such a medium facilitates the retention of the dye on the recording surface, enabling more efficient sublimation of the dye in the subsequent transfer process.

[0100] 2.2. Transfer process

[0101] The recording method according to this embodiment includes a transfer step in which the recording surface of transfer paper coated with ink is placed opposite a recording medium such as polyester fabric, which is a printed material. Specifically, the fabric is placed on the recording surface of the transfer paper, and the dye is heated to sublimely transfer the dye to the printed material. This results in a printed material, i.e., a printed article, using the fabric as the printed material.

[0102] The heating temperature in the transfer step is preferably 160° C. to 220° C., more preferably 170° C. to 200° C. This allows sufficient energy to be applied to transfer the dye to the substrate, resulting in excellent productivity of printed materials.

[0103] The heat-up time in the transfer process also depends on heating temperature, but is preferably 30 seconds with and below 90 seconds, more preferably above 45 seconds and below 60 seconds.Thus, can obtain enough energy so that the dye transfer is to the printed object, can make the productivity of printed material more excellent.

[0104] The transfer process can be performed by heating the transfer paper coated with ink while the transfer paper is placed opposite the object to be printed, but is preferably performed by heating the transfer paper while the transfer paper is in close contact with the object to be printed. This allows, for example, a printed material with a clearer image recorded on a cloth or the like to be obtained.

[0105] As the recording medium, that is, the printed object, for example, polyester cloth, which is a water-repellent fiber cloth, can be cited, but sheet-like materials such as resin films, and materials having three-dimensional shapes other than sheet shapes, such as spherical, rectangular, and curved objects, can also be used.

[0106] 2.3. Other processes

[0107] The recording method according to this embodiment may also include a step of heating the transfer paper after the ink adhesion step. This step involves heating the transfer paper after the ink is sprayed onto the transfer paper and adhered. This step promotes drying of the ink adhered during the ink adhesion step, suppresses image blurring, and also prevents print-through. Print-through refers to the phenomenon in which ink components migrate toward the back surface of the transfer paper, which is in contact with the recording surface, when the transfer paper is overlapped, such as by being wound around a roller.

[0108] The transfer paper's ultimate temperature in this step is preferably 60° C. or higher, and more preferably 70° C. or higher and 120° C. or lower. Within this range, the dye is less likely to sublime, and a good drying speed can be achieved.

[0109] Example

[0110] Hereinafter, the present invention will be described in more detail using Examples and Comparative Examples. However, the present invention is not limited to the following Examples.

[0111] 1. Preparation of ink composition for dye solubility evaluation

[0112] (Ink compositions 1 to 3)

[0113] To achieve the compositions shown in Table 1, each component was added to a mixing tank and mixed and stirred for 2 hours using a magnetic stirrer to obtain ink compositions 1 to 3 for dye solubility evaluation. The values in Table 1 are expressed in mass %. The mass % of disperse dyes is expressed as solids content. Deionized water was used as water, and the mass of each ink composition was added to 100.0 mass %. The components shown in Table 1 are described below.

[0114] 2. Preparation of inkjet ink composition for dye printing

[0115] (Examples 1 to 12 and Comparative Examples 1 to 18)

[0116] The components were added to a mixing tank to obtain the compositions shown in Tables 2 to 4, mixed and stirred for 2 hours using a magnetic stirrer, and then filtered through a membrane filter with a pore size of 1 μm to obtain the dye-based inkjet ink compositions of Examples and Comparative Examples.

[0117] The numerical values in Tables 2 to 4 represent mass %. The components shown in Tables 1 to 4 are as follows.

[0118] Disperse dyes

[0119] Disperse Red 60…CI Disperse Red 60 (commercially available)

[0120] Disperse Yellow 54…CI Disperse Yellow 54 (commercially available)

[0121] Disperse Blue 359…CI Disperse Blue 359 (commercially available)

[0122] Disperse Orange 25…CI Disperse Orange 25 (commercially available)

[0123] Dispersant

[0124] ·Naphthalenesulfonic acid formaldehyde condensate Na…Naphthalenesulfonic acid formaldehyde condensate sodium

[0125] ·Sodium ligninsulfonate…Sodium ligninsulfonate

[0126] 〔Water-soluble organic solvent〕

[0127] ·glycerin

[0128] Propylene glycol

[0129] [Penetrating solvent]

[0130] 1,5-Pentanediol

[0131] 1,2-Butanediol

[0132] 3-Methyl-1,5-pentanediol

[0133] Polyethylene glycol monomethyl ether

[0134] [Other water-soluble organic solvents]

[0135] N-Hydroxyethyl-2-pyrrolidone

[0136] 1,2-Hexanediol

[0137] 2-Pyrrolidone

[0138] 2,3-Butanediol

[0139] Ethylene glycol monoisopropyl ether

[0140] 〔Surfactant〕

[0141] BYK348…BYK-348 (manufactured by BYK Chemicals Japan Ltd., silicone-based surfactant)

[0142] pH adjuster

[0143] Triethanolamine

[0144] 3. Evaluation Method

[0145] 3.1. Dye solubility

[0146] First, the dye solubility evaluation ink compositions 1 to 3 obtained above were added to the respective penetrating solvents or other organic solvents to obtain dispersions. Specifically, the dye solubility evaluation ink compositions and the penetrating solvent or other organic solvent were placed in a mixing container so that the total solid content of the disperse dye contained in the dye solubility evaluation ink composition relative to the penetrating solvent or other organic solvent was 5.0% by mass. The mixture was then stirred for 2 hours using a magnetic stirrer to obtain the respective dispersions.

[0147] The resulting dispersions were heated at 60°C for 1 hour. Afterwards, they were cooled to room temperature (25°C) and allowed to stand at that temperature for 4 days. The dye solubility was evaluated by visual inspection of the dispersions after standing, according to the following criteria.

[0148] Furthermore, dispersions containing no penetrating solvent or other organic solvent, namely, ink compositions 1 to 3 for dye solubility evaluation, were heated in the same manner as described above and allowed to stand at room temperature for 4 days. The dye solubility of the dispersions after standing was then evaluated.

[0149] Table 5 shows the results.

[0150] (Benchmark)

[0151] A: The disperse dye is dissolved in the dispersion and no insoluble components are found.

[0152] B: The disperse dye was dissolved in the dispersion, but insoluble components were found.

[0153] C: A part of the disperse dye was not dissolved in the dispersion liquid, and an insoluble component was observed.

[0154] 3.2. Ink storage stability

[0155] About 50 mL of the dye-based inkjet ink compositions of Examples 1 to 4 and Comparative Examples 1 to 6 were degassed and sealed in aluminum bags capable of sealing the ink. Two aluminum bags were prepared for each ink composition.

[0156] One of the aluminum bags was left at 60° C. for 5 days and then cooled to room temperature (25° C.) The ink composition was taken out from the cooled aluminum bag to obtain an evaluation ink composition 1.

[0157] The other aluminum bag was left standing at room temperature for 5 days, and the ink composition was taken out from the aluminum bag after standing to obtain an ink composition 2 for evaluation.

[0158] The viscosity, surface tension, particle size, and pH of evaluation ink compositions 1 and 2 were measured, and if the following criteria were met, the ink composition was rated A. The A ratings were counted, and dye-based inkjet ink compositions with three or more A ratings were designated A, while the remaining A ratings were designated D. The ink compositions were then evaluated for ink storage stability.

[0159] Table 6 shows the results.

[0160] (Baseline: A rating)

[0161] Viscosity: The viscosity of the ink composition 1 for evaluation was the same as that of the ink composition 2 for evaluation.

[0162] Surface tension: The surface tension of ink composition 1 for evaluation was the same as that of ink composition 2 for evaluation.

[0163] Particle size: The particle size of the ink contained in the evaluation ink composition 1 was changed by 15 nm or less compared to the particle size of the disperse dye contained in the evaluation ink composition 2.

[0164] pH: The pH of the evaluation ink composition 1 and the pH of the evaluation ink composition 2 varied within ±0.2.

[0165] 3.3. Generation of foreign matter

[0166] Approximately 10 mL of each of the dye-based inkjet ink compositions of Examples 1 to 12 and Comparative Examples 1 to 18 was placed in a sealed glass storage bottle and allowed to stand at 60°C for 5 days. The bottles were then cooled to room temperature (25°C) and the ink compositions were removed from the bottles to obtain Evaluation Ink Composition 3. Each Evaluation Ink Composition 3 was filtered through a 10 μm-diameter metal mesh filter. The number of solid particles remaining on the metal mesh filter per 1 mm square was counted, and the generation of solid matter, which constitutes foreign matter, was evaluated according to the following criteria.

[0167] Table 7 shows the results.

[0168] (Benchmark)

[0169] A: No solid matter was found per 1 mm square.

[0170] B: Solid matter was found per 1 mm square, but the number was not enough to cause a practical problem.

[0171] C: Solid matter was found per 1 mm square, which is a number that is problematic in practical use.

[0172] 3.4. Ejection reliability

[0173] The dye-based inkjet ink compositions of Examples 1 to 4 and Comparative Examples 1 to 6 were each filled into an ink cartridge of an inkjet printer, PX-930G (trade name, manufactured by Seiko Epson Corporation). The ink compositions were then ejected from all nozzles, and a verification pattern was recorded to indicate the ink landing position. The verification pattern confirmed normal ejection for all ink compositions. The printer was then powered off, the print head moved to its normal standby position, and after confirming that the inkjet head was capped, the printer, with the ink cartridges installed, was placed in a constant-temperature chamber at 40°C and 20% RH.

[0174] Afterwards, the printer was removed from the thermostatic chamber and cooled to room temperature (25°C). The printer was powered on, and the ink composition was ejected from all nozzles of the head to confirm normal printing. If any nozzles failed to eject the ink composition, the head was cleaned, and the ink composition was ejected from all nozzles. The number of cleaning cycles required until normal printing was restored was counted. Based on this number of cycles, ejection reliability was evaluated according to the following criteria.

[0175] The results are shown in Table 6. In addition, "-" in Table 6 means that the test was not carried out. (Baseline)

[0176] A: If the cleaning frequency is less than 2 times, normal printing can be carried out.

[0177] B: The machine can recover from the blockage after cleaning more than 3 times and less than 6 times, and can print normally.

[0178] C: The clogging cannot be recovered even after cleaning is performed 7 or more times.

[0179] 3.5. Ejection stability

[0180] The dye-based inkjet ink compositions of Examples 1-4 and Comparative Examples 1-6 were each filled into an ink cartridge of an inkjet printer, PX-930G (trade name, manufactured by Seiko Epson Corporation). The printer, with the inkjet head uncovered, was left at room temperature for 20 minutes. After this period, the head was cleaned once, and after printing 20 solid patterns, an ink check pattern was printed. Nozzle dropout and drift were visually observed. Based on these observations, ejection stability was evaluated according to the following criteria.

[0181] The results are shown in Table 6. In addition, "-" in Table 6 means that the test was not carried out. (Baseline)

[0182] A: Among the 180 nozzles, no nozzles were found to be missing or misaligned.

[0183] B: Among 180 nozzles, one or more and 30 or fewer nozzles were found to have fallen out or shifted.

[0184] As shown in Tables 5 to 7, it can be seen that the ink composition of this embodiment can provide an ink composition having a higher level of excellent storage stability and ejection stability.

[0185] As shown in Tables 6 and 7, it can be seen that when the sodium salt of naphthalenesulfonic acid formaldehyde condensate is used as the dispersant, an ink composition having even higher and excellent storage stability and ejection stability can be obtained.

[0186] As shown in Tables 6 and 7, it was found that the ink composition containing one or more disperse dyes selected from the group consisting of CI Disperse Red 60 and CI Disperse Orange 25 had even higher and superior storage stability and ejection stability.

[0187] As shown in Tables 5 to 7, it can be seen that when polyethylene glycol monomethyl ether is used as the penetrating solvent, an ink composition having further high and excellent storage stability and ejection stability can be obtained.

Claims

1. An inkjet ink composition for dye printing, characterized in that The ink composition comprises a disperse dye, a dispersant, a water-soluble organic solvent, a penetrating solvent and water, The water-soluble organic solvent comprises glycerol and propylene glycol, The osmotic solvent includes one or more selected from the group consisting of 1,5-pentanediol, 1,2-butanediol, 3-methyl-1,5-pentanediol, and polyethylene glycol monomethyl ether.

2. The inkjet ink composition for dye printing according to claim 1, characterized in that The dispersant includes one or more selected from the group consisting of a sodium salt of a naphthalenesulfonic acid formaldehyde condensate and a sodium salt of a ligninsulfonic acid.

3. The inkjet ink composition for dye printing according to claim 1, characterized in that The disperse dye includes one or more selected from the group consisting of CI Disperse Red 60 and CI Disperse Orange 25.

4. The inkjet ink composition for dye printing according to claim 1, characterized in that The content of the disperse dye is 5.0% by mass or more relative to the total amount of the ink composition. The content of the dispersant is 5.0% by mass or more relative to the total amount of the ink composition.

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