Aqueous inkjet composition for textile printing

Abstract

An aqueous ink for textile printing includes a disperse dye, a first dispersant selected from the group consisting of an alkali metal salt of an aromatic sulfonic acid, an alkali metal salt of an aromatic sulfonic acid-formalin condensate, an alkali metal salt of a beta-naphthalenesulfonic acid, and an alkali metal salt of a beta-naphthalenesulfonic acid-formalin condensate, and a second dispersant selected from the group consisting of an alkali metal salt of an aromatic sulfonic acid-formalin condensate and an alkali metal salt of a beta-naphthalenesulfonic acid-formalin condensate. The second dispersing agent is a copolymer of acrylate and alkylene oxide.

Description

Technical Field

[0001] The present invention relates to an aqueous inkjet ink containing disperse dyes as water-insoluble coloring materials, which is used for printing synthetic substrates such as textile materials and sheets for transfer printing. The present invention also includes a recording method, a dyeing method and a coloring method by inkjet using the ink composition. Background Art

[0002] In recent years, the use of inkjet printing has expanded, and has been applied not only to printers used in offices or homes but also to commercial printing, textile printing, and the like.

[0003] Inkjet inks containing disperse dyes have been used for industrial dyeing of hydrophobic fibers such as polyester. Disperse dyes penetrate and diffuse into the fibers under high temperature conditions and are fixed by hydrogen bonds, intermolecular forces, etc. between the fibers and the dyes.

[0004] Printing methods for such inkjet inks include direct printing methods, in which the ink is printed on a recording medium to be dyed (usually composed of fibers), and the dye is then fixed by heat treatment such as steaming or calendering; and also include thermal transfer printing methods, in which the dye ink is printed on an intermediate transfer medium (transfer paper), and the dye is then sublimated and transferred from one side of the intermediate transfer medium to the recording medium to be dyed.

[0005] Due to the long-term dispersion stability problem of the disperse dye, the inkjet ink containing the disperse dye generally has the problem that the ink storage stability is low and the ejection reliability in the inkjet method is also poor.

[0006] In EP 3 546 535 A an aqueous inkjet composition is disclosed comprising a disperse dye, an anionic dispersant such as lignin sulfonic acid in combination with a dispersant selected from derivatives of styrene maleic acid, styrene maleimide, ethylene oxide adducts of tristyrylphenol and ethylene oxide adducts of tristyrylphenol.

[0007] JP2015091906 A discloses an aqueous inkjet composition comprising a disperse dye, an anionic dispersant (such as lignin sulfonic acid) in combination with an ethylene oxide adduct of phytosterol and an ethylene oxide adduct of cholestanol.

[0008] EP 3 546 535 A and JP 2015091906 A both claim that a combination of dispersants improves the storage stability of aqueous disperse dye inks. While this improvement may apply to inks containing a single disperse dye, it is not the case for inks containing multiple disperse dyes, such as for black inks.

[0009] US2015337153 A discloses an inkjet ink set for sublimation transfer, comprising a first ink composition containing a disperse dye and a first dispersant; and a second ink composition containing a disperse dye and a second dispersant, each dispersant containing a salt of an aromatic sulfonic acid.

[0010] The composition in the above-mentioned patent application causes improvement in the discharge stability of aqueous inkjet inks containing lignin sulfonic acid.

[0011] WO 2014 / 127050 A1 discloses a combination of a PEO-PPO based dispersant and lignin sulfonate to improve the color fastness of direct inkjet printing on polyester fabrics.

[0012] Therefore, there is still a need for an aqueous inkjet ink containing disperse dyes which also exhibits reliable jetting behavior for inks comprising a mixture of disperse dyes and shows improved image quality. SUMMARY OF THE INVENTION

[0014] It is an object of the present invention to provide a solution to the above mentioned problems. This object has been achieved by incorporating an aromatic sulfonic acid and a dispersant into an aqueous inkjet ink comprising a disperse dye as defined in claim 1, the dispersant being a copolymer of an acrylate and an alkylene oxide.

[0015] According to another aspect, the present invention comprises an aqueous inkjet ink set as defined in claim 11 .

[0016] According to another aspect, the present invention comprises a method for inkjet dyeing, characterized in that after the ink composition according to claim 1 is provided to the hydrophobic fiber by means of an inkjet as defined in claim 13, the coloring material is fixed to the hydrophobic fiber by means of a steaming or baking treatment.

[0017] Other features, elements, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention. Specific embodiments of the present invention are also defined in the dependent claims. DETAILED DESCRIPTION OF THE INVENTION

[0019] A. Aqueous Inkjet Ink Compositions

[0020] The ink for inkjet textile printing of the present invention comprises water, disperse dye, a first dispersant and a second dispersant, wherein the first dispersant is selected from alkali metal salts of aromatic sulfonic acid, alkali metal salts of aromatic sulfonic acid-formalin condensate, alkali metal salts of β-naphthalenesulfonic acid and alkali metal salts of β-naphthalenesulfonic acid-formalin condensate, and the second dispersant is a copolymer of acrylic acid ester and alkylene oxide.

[0021] A.1. First dispersant

[0022] The first dispersant is selected from the group consisting of alkali metal salts of aromatic sulfonic acids, alkali metal salts of aromatic sulfonic acid-formalin condensates, alkali metal salts of β-naphthalenesulfonic acid, and alkali metal salts of β-naphthalenesulfonic acid-formalin.

[0023] The preferred first dispersant is a lignin sulfonate. Examples thereof include Vanillex N, Vanillex RN, Vanillex G and Pearllex DP (all manufactured by Nippon Paper Industries, Ltd.), REAX 85A, REAX 907, Vanisperse CB, Diwatex XP-9, REAX WSD and REAX 105M, etc. Vanisperse is most preferred because it has a positive effect on feathering and L value of sublimation prints.

[0024] Examples of the first dispersant other than lignin sulfonate include formalin condensates of high molecular weight sulfonic acids (preferably aromatic sulfonic acids), salts thereof or mixtures thereof (hereinafter, referred to as "sulfonic acid formalin" unless otherwise specified. When the term "condensate" is used, the term "condensate" includes at least one dispersant selected from "these salts or mixtures thereof").

[0025] Examples of "these salts" include salts such as sodium salts, potassium salts and lithium salts. Examples of formalin condensates of aromatic sulfonic acids include creosote sulfonic acid, cresol sulfonic acid, phenol sulfonic acid, β-naphthalene sulfonic acid, β-naphthalene sulfonic acid, β-naphthalene sulfonic acid and β-naphthalene sulfonic acid. Examples thereof include formalin condensates such as cresol sulfonic acid and 2-naphthol-6-sulfonic acid. Among them, creosote sulfonic acid and β-naphthalene sulfonic acid formalin condensate are preferred.

[0026] For example, formalin condensates of creosote sulfonic acid are Laberin W series (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), Demor C (manufactured by Kao Co., Ltd.); formalin condensates of methylnaphthalene sulfonic acid are laberin.AN series (both manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.); and the like.

[0027] Examples of the formalin condensate of β-naphthalenesulfonic acid include Demor N; and examples of the formalin condensate of the specific aromatic sulfonic acid include Demor SN-B (both manufactured by Kao Co., Ltd.).

[0028] The amount of the first dispersant in the aqueous ink according to the present invention, and more specifically the amount of the lignin sulfonate, is 0.1 wt % to 7 wt %, more preferably 1 wt % to 5 wt %, relative to the total weight of the ink. An amount below the lower level of the above range does not bring any substantial benefits regarding ink stability or image quality. An amount above the higher level of the above range will have too great an effect on chromaticity and result in unacceptable wet rubbing fastness.

[0029] The first dispersant can be added during the preparation of the disperse dye dispersion. The first dispersant should preferably be added during the grinding or homogenization step in the preparation of the dispersion. Optionally, the first dispersant can also be added during the preparation of the ink composition, thus adding after the preparation of the disperse dye dispersion.

[0030] A.2. Second dispersant

[0031] Preferably, the inkjet ink according to the invention comprises a polymeric dispersant as a second dispersant. Examples of useful polymeric dispersants include copolymers of acrylates and alkylene oxides, copolymers having a polyacrylate backbone with alkylene oxide groups, which are preferably present as side chains.

[0032] The second dispersant is preferably added during the preparation of the disperse dye dispersion, more preferably during the grinding or homogenization step in the preparation of the dispersion.

[0033] The amount of the second dispersant in the aqueous ink according to the present invention, and more specifically the amount of the lignin sulfonate, is 0.1 wt % to 7 wt %, more preferably 1 wt % to 3 wt %, relative to the total weight of the ink. Amounts below the above range do not bring any substantial benefits regarding the stability of the disperse dye. Amounts above the above range increase costs and have a negative impact on the stability of the dispersion.

[0034] Most preferred dispersants are copolymers, such as Disperbyk 2010 from Byk Chemie or Edaplan 482 from Munzing Chemie.

[0035] A.3. Dispersions of disperse dyes

[0036] The base of the ink of the present invention is a dispersion of disperse dyes. The dispersion comprises a vehicle, preferably water, at least one disperse dye, a second dispersant (see §A.2) and optionally a first dispersant (see §A.1.).

[0037] A.3.1. Preparation of disperse dye dispersion

[0038] The dispersion method comprises the step of making a premix of the vehicle and the second dispersant.The first dispersant may be added simultaneously with the second dispersant, or therefore added after the second dispersant.

[0039] Once the premix is ​​prepared, the predispersion is made by mixing the disperse dye with the premix. In this step, the first dispersant may also be added.

[0040] In another embodiment, the predispersion can be produced directly by mixing the binder with the disperse dye, the secondary dispersant and optionally the primary dispersant in one step.

[0041] Subsequently, high shear forces or grinding are applied to the obtained predispersion, whereby a stable dispersion of the disperse dye is obtained.

[0042] The dispersion method for obtaining a stable dispersion of the disperse dye may be arbitrarily selected as long as it is a method for breaking up agglomerates of particles and uniformly dispersing the disperse dye in the vehicle.

[0043] The equipment that is suitable for dispersing this disperse dye comprises pressure kneading machine, open kneading machine, planetary mixer, dissolver and Dalton universal mixer.Other suitable grinding and dispersing equipment comprises ball mill, bead mill, colloid mill, high speed dispersor, double roller mill (double rollers), sand mill (bead mill), paint conditioning machine and three roller mill.Also can use ultrasonic energy to prepare this dispersion.

[0044] Many different types of materials can be used as grinding media, such as glass, ceramic, metal and plastic. In a preferred embodiment, the grinding media can comprise particles, preferably substantially spherical, such as beads consisting essentially of a polymer resin or yttrium stabilized zirconia beads.

[0045] During the mixing, grinding and dispersing processes, each process is preferably performed under cooling to prevent heat accumulation.

[0046] The addition of the first dispersant can be carried out before, during or after the process of applying high shear force or grinding. It is preferred to add the first dispersant before the process of applying high shear force or grinding.

[0047] The ratio of the amount of the first dispersant relative to the amount of the disperse dye is preferably 0.04 to 1, more preferably 0.05 to 0.8, and most preferably 0.06 to 0.6. Ratios below these ranges result in insufficient effect of the presence of the first dispersant on image quality (feathering), and ratios above these ranges result in unacceptable chromaticity changes in the ink color and unacceptable wet rubbing fastness.

[0048] The ratio of the amount of the second dispersant to the amount of the disperse dye is preferably 0.2 to 1.

[0049] Without wishing to be bound by theory, it is believed that the first dispersant acts as a synergist with the second dispersant, which results in a stable dispersion, thereby producing a stable and high performance ink.

[0050] The concentration of the disperse dye is from 10 to 60% by weight, preferably from 15 to 55% by weight, and more preferably from 25 to 50% by weight, relative to the total weight of the dispersion of the present invention.

[0051] The particle size of the disperse dye can be controlled by the high shear application or the processing time of the grinding. More specifically, by increasing the processing time, the disperse dye particles can be made smaller and the amount of particle screen overburden can be reduced.

[0052] Preferably, disperse dye particles of the present invention have 1 μ m or less, preferably 500 nm or less, more preferably 250 nm or less average particle size. If average particle size is higher than these values, due to the blocking of inkjet nozzle, the problem of jetting reliability will occur. Simultaneously, the amount of the particle sieve feed with a particle size exceeding 1.125 μ m should be lower than the reliable jetting of the ink that guarantees to comprise the disperse dye dispersion.

[0053] By means of the above-mentioned production method, a stable disperse dye dispersion is obtained, which can be used for preparing the disperse dye inkjet ink according to the present invention.

[0054] A.2.2. Disperse dyes

[0055] The ink composition of the present disclosure includes at least one disperse dye.

[0056] Suitable disperse dyes include any dye identified as disperse dyes by Colour Index International in Colour Index, www.colour-index.Corn, which is incorporated herein by reference in its entirety. Examples of disperse dyes are given in Colour Index, 3' Edition, pages 2479 to 2742, which are incorporated herein by reference in its entirety. Each disperse dye described therein is also incorporated herein by reference.

[0057] Suitable disperse dyes that may be used in the inks described herein include all dyes that are considered disperse.

[0058] Examples of disperse dyes for use in the present invention include azo dyes, anthraquinone dyes, quinophthalone dyes, styryl dyes, oxazine dyes, xanthene dyes, methine dyes and azomethine dyes. In this class of dyes, examples of yellow disperse dyes include "CI Disperse Yellow 3, 4, 5, 7, 9, 13, 23, 24, 30, 33, 34, 42, 44, 49, 50, 51, 54, 56, 58, 60, 63, 64, 65, 66, 68, 71, 74, 76, 79, 82, 83, 85, 86, 88, 90, 91, 93, 98, 99, 100, 104, 108, 114, 116, 118, 119, 122, 124 , 126, 135, 140, 141, 149, 160, 162, 163, 164, 165, 179, 180, 182, 183, 184, 186, 192, 198, 199, 201, 202, 204, 210, 211, 215, 216, 218, 224, 227, 231 and 232. Examples of orange disperse dyes include "CI Disperse Orange 1, 3, 5, 7, 11, 13, 17, 20, 21, 25, 29, 30, 31, 32, 33, 37, 38, 42, 43, 44, 45, 46, 47, 48, 49, 50, 53, 54, 55, 56, 57, 58, 59, 61, 62, 66, 71, 73, 76, 78, 80, 89, 90, 91, 93, 96, 97, 119, 127, 130, 139, 142 and 155.Examples of red disperse dyes include "CI Disperse Red 1, 4, 5, 7, 11, 12, 13, 15, 17, 27, 43, 44, 50, 52, 53, 54, 55, 56, 58, 59, 60, 65, 67.1, 72, 73, 74, 75, 76, 78, 81, 82, 86, 88, 90, 91, 92, 93, 96, 103, 105, 106, 107, 108, 110, 111, 113, 117, 118, 121, 122, 126, 127, 128, 131, 132, 134, 135, 137, 143, 145, 146, 151, 152, 153, 154, 157, 159, 164, 167, 169, 177, 179, 181, 183, 184, 185, 188, 189, 190, 191, 192, 200, 201, 202, 203, 205, 206, 207, 210, 221, 224, 225, 227, 229, 239, 240, 257, 258, 277, 278, 279, 281, 288, 298, 302, 303, 310, 311, 312, 320, 324, 328 and 343. Examples of blue disperse dyes include CI Disperse Blue 3, 7, 9, 14, 16, 19, 20, 26, 27, 35, 43, 44, 54, 55, 56, 58, 60, 62, 64, 71, 72, 77, 73, 75, 79, 81, 82, 83, 87, 91, 93, 94, 95, 96, 102, 106, 108, 112, 113, 115, 118, 120, 122, 125, 128, 130, 139, 141, 142, 143, 146, 148, 149, 153, 154, 158, 165, 166 7, 171, 173, 174, 176, 181, 183, 185, 186, 187, 189, 197, 198, 200, 201, 205, 207, 211, 214, 224, 225, 257, 259, 267, 268, 270, 281, 284, 285, 287, 288, 291, 293, 295, 297, 301, 315, 330, 333, 354, 359, 360, 366, 367 and 373. Most preferably, the Disperse Blue 360 ​​is used as the disperse dye for aqueous inkjet ink of the present invention.The example of other disperse dye comprises " CI Disperse Violet 1,4,8,23,26,27,28,31,33,35,36,38,40,43,46,48,50,51,52,56,57,59,61,63,69,77 and 93.Without particular limitation, examples of black disperse dyes include CI Disperse Black 1, 3, 10 and 24. Without particular limitation, examples of brown disperse dyes include Disperse Brown 27. Examples of dye types other than the above dyes include "CI Solvent Yellow 160", "CI Solvent Green 3" and 163, and "CIVat Red 41".

[0059] In general, these disperse dyes are preferably contained in an amount of 0.2 to 12% by weight, and more preferably 0.5 to 10% by weight, relative to the total mass of the ink, because dispersion stability can be maintained and a desired printing density can be achieved.

[0060] A.3. Water-miscible solvents

[0061] The aqueous inkjet ink according to the present invention may contain a water-miscible organic solvent. In the present invention, this may include glycerol, diglycerol, polyglycerol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 2-pyrrolidone, N-methylpyrrolidone, dimethyl sulfoxide and sulfolane.

[0062] From the viewpoint of moisturizing properties, among water-miscible organic solvents, glycerol, diethylene glycol, triethylene glycol, polyethylene glycol (average molecular weight is 200 to 600), dipropylene glycol and tripropylene glycol are preferably used, and glycerol, diethylene glycol and dipropylene glycol are more preferred. Among these solvents, glycerol is particularly preferred.

[0063] Other examples include propylene glycol, dipropylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,3-butanediol, 1,2-pentanediol, 1,5-pentanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol, 1,2-hexanediol, and 1,6-hexanediol.

[0064] Examples of glycol ethers include monoalkyl ethers of glycols selected from ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol and tripropylene glycol. More specifically, triethylene glycol monomethyl ether, triethylene glycol monobutyl ether and dipropylene glycol monopropyl ether can be preferably exemplified. These solvents can be used alone or in combination of two or more.

[0065] From the viewpoint of regulating the viscosity of the ink and preventing clogging of the nozzles of the inkjet print head by the wetting effect, these water-miscible organic solvents are preferably contained in an amount of 1 to 50 wt %, more preferably 30 to 45 wt %, and particularly preferably 30 to 40 wt %, relative to the total mass of the ink.

[0066] A.4. Surfactants

[0067] In order to adjust the surface tension of the ink, a surfactant may be used, and examples thereof include anionic surfactants, amphoteric surfactants, cationic surfactants, and nonionic surfactants.

[0068] Examples of the anionic surfactant include alkyl sulfocarboxylates, α-olefin sulfonates, polyoxyethylene alkyl ether acetates, N-acylamino acids and salts thereof, N-acylmethyl taurates, alkyl sulfate polyoxyalkyl ether sulfates, alkyl sulfate polyoxyethylene alkyl ether phosphates, rosin acid soaps, castor oil sulfate, lauryl sulfate, alkylphenol type phosphates, alkyl type phosphates, alkylaryl sulfonates, diethyl sulfosuccinate, diethylhexyl sulfosuccinate and dioctyl sulfosuccinate.

[0069] Examples of the amphoteric surfactant include lauryl dimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, coconut oil fatty acid amide propyl dimethylaminoacetic acid betaine, polyoctyl polyaminoethyl glycine and other imidazoline derivatives thereof.

[0070] Examples of cationic surfactants include 2-vinylpyridine derivatives and poly-4-vinylpyridine derivatives. Other examples of cationic surfactants are quaternary ammonium salts of long-chain aliphatic tertiary amines, such as cetyltrimethylammonium bromide, cetyldimethylbenzylammonium chloride and hydroxyethyldimethyldodecylammonium chloride, and quaternary salts of nitrogen-containing heteroaromatic rings, such as hexadecylpyridinium bromide and quaternized imidazoles and benzimidazoles. Other examples are protonated long-chain aliphatic amines, such as the hydrochloride of dimethylhexadecylamine and the toluenesulfonate of diethyldodecylamine.

[0071] Examples of nonionic surfactants include ether-based surfactants such as polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether and polyoxyethylene alkyl ether; ester-based surfactants such as polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate and polyoxyethylene stearate; and acetylenediol (alcohol)-based surfactants such as 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol and 3,5-dimethyl-1-hexyne-3-ol.

[0072] B.Inkjet ink set

[0073] Another preferred embodiment of the present invention is to manufacture an aqueous inkjet ink set, wherein at least one of its inks is an aqueous ink containing a disperse dye, a first dispersant and a second dispersant, wherein the first dispersant is selected from alkali metal salts of aromatic sulfonic acids, alkali metal salts of aromatic sulfonic acid-formalin condensates, alkali metal salts of β-naphthalenesulfonic acid and alkali metal salts of β-naphthalenesulfonic acid-formalin condensates, and the second dispersant is a copolymer of an acrylate and an alkylene oxide.

[0074] More preferably, the cyan ink or magenta ink of the CMY or CMYK inkjet ink set and the black ink of the CMYK inkjet ink set are aqueous inks containing the disperse dye, the first dispersant, and the second dispersant as described above.

[0075] C. Inkjet Recording Method

[0076] The method of inkjet recording, more particularly the method of inkjet textile printing using the ink of the present invention as described above, can be carried out as follows. First, the ink for inkjet textile printing is placed in a piezoelectric, thermal or continuous inkjet printer, and then sprayed on a fabric containing hydrophobic fibers such as polyester fibers. Pretreatment may be applied to the hydrophobic fibers to prevent blurring.

[0077] After the spraying step, the fabric is optionally heated to dry the image, followed by heating the printed fabric under pressure at a temperature of 150° C. to 220° C. for 0.5 to 15 minutes. Preferably, the heating time is 40 to 60 seconds. A variety of heating methods can be used, but calandering and steam heating are preferably used. Hydrophobic fibers (such as polyester fibers) are dyed with the disperse dyes of the ink. Subsequently, unfixed disperse dyes, additives such as dispersants, pretreatment agents, and the first and second dispersants can be removed by washing or reduction cleaning or reduction removal and washing with water. After drying the fabric, a dyeing product with an image printed thereon is provided. In the case of direct printing, the dyeing product further contains the first and second dispersants present in the ink.

[0078] The inkjet recording method according to the present invention may also include a step of transferring to a fabric or object coated with a synthetic polymer suitable for receiving disperse dyes using an intermediate transfer medium. As an intermediate transfer medium (which is not particularly limited), for example, paper such as plain paper or a recording medium provided with an ink-absorbing layer based on porosity or swelling (which is referred to as paper or coated paper specifically for inkjet) can be used. Among these, paper provided with an ink-absorbing layer formed by inorganic fine particles such as silicon dioxide is preferred. In the process of drying the inkjet ink composition for sublimation transfer attached to the intermediate transfer medium, an intermediate transfer medium in which bleeding is suppressed can be obtained, and in the following transfer step, the sublimation of the disperse dye tends to proceed more smoothly.

[0079] The transfer step is a step of transferring the disperse dye contained in the inkjet ink composition to a fabric or an object coated with a synthetic polymer suitable for receiving the disperse dye by heating the surface of the intermediate transfer medium on which the inkjet ink according to the present invention is ejected and the surface of the fabric or the object coated with, for example, PES in a state where they face each other.

[0080] The heating temperature in the transfer step, which is not particularly limited, is preferably 160 to 220° C., and more preferably 170 to 200° C. When the heating temperature is within the above range, sublimation of the dye is sufficient to obtain high color density while avoiding shrinkage and deformation of the fabric.

[0081] The heating time in this step (which also depends on the heating temperature) is 30 to 150 seconds, and more preferably 45 to 90 seconds. When the heating time is in the above range, there is a tendency that the energy required for transfer may be smaller and the productivity of the recorded matter improves.

[0082] D. Examples

[0083] D.1. Materials

[0084] Unless otherwise stated, all materials used in the following examples are readily available from standard sources such as Merck and ACROS (Belgium). The water used was deionized water.

[0085] DB 360: Disperse blue 360 ​​is a disperse dye purchased under the trade name Riaplas Blue DB TP, supplied by Rialco

[0086] DO 25: Disperse orange 25 is a disperse dye with the trade name Riaplas orange 2RL TP, supplied by Rialco

[0087] DY 54: Disperse yellow 54 is a disperse dye purchased under the trade name Riaplas Yellow 3GL TP, supplied by Rialco

[0088] DR 60: Disperse red 60 is a disperse dye with the trade name Riaplas Red 2BL TP, supplied by Rialco

[0089] DB359: Disperse blue 359 is a disperse dye purchased under the trade name Riaplas blue 3GL-TPM, supplied by Rialco

[0090] Disperbyk 2010 is a 40% emulsion of a styrene butyl acrylic copolymer with polyethylene glycol moieties from BYK Chemie

[0091] ·Edaplan TM 482 is a polymer dispersant from MUNZING

[0092] Dispex TM Ultra PX 4585 is a high molecular weight dispersant available from BASF as (50% aqueous solution)

[0093] Bykjet 9170 is a 40% solution of a copolymer with pigment-affinic groups from BYK Chemie

[0094] Proxelk-D3798 is a 5% solution of CASnr127553-58-6 manufactured by PROM CHEM UK

[0095] VANI is Vanisperse CB, a lignin sulfonate supplied by Borregaard

[0096] Reax LS is a lignin sulfonate from Ingevity

[0097] Rhodoline 3400 is a nonionic wetting and dispersing agent manufactured by Solvay

[0098] Disperbyk 190 is a 40% solution of a high molecular weight block copolymer with pigment-affinic groups, CASnr 216303-28-5 manufactured by BYK chemie

[0099] GLY is glycerol

[0100] PD is 1,3-propylene glycol, supplied by IMCD

[0101] SURF is Surfynol 104H produced by Evonik

[0102] DI water is deionized water

[0103] D.2. Measurement methods

[0104] D.2.1. Average particle size of disperse dye dispersion

[0105] Based on the principle of dynamic light scattering, using Zetasizer TMNano-S (Malvern Instruments, Goffin Meyvis) measures the average particle size of disperse dye particles in the dispersion. For reliable inkjet properties (jetting quality and printing quality), the average particle size of the dispersed particles is preferably below 250 nm.

[0106] D.2.2. Viscosity of dispersion

[0107] The viscosity of the disperse dye dispersions was evaluated using an Anton Paar MCR302 rheometer in a cone and plate setup. -1 The viscosity is measured at a shear rate of 1.

[0108] D.2.3. Application of comparative ink and inventive ink

[0109] A 4 μm bar coating of the ink was made on a polyester backlit substrate using an Elcometer 4340 using a 4 μm spiral bar and sublimated using a calender (with belt and heated oil drum) at 190°C with a contact time of 54 seconds.

[0110] D.2.4. L value of ink

[0111] The ink was diluted 10 times with deionized water and coated according to §D.2.3. The color of the ink coating was measured using a Gretag SPM50 with D65 illumination at an observation angle of 10°. The evaluation was performed according to Table 1.

[0112] Table 1

[0113] L value Score <26 A 26-28 B >28 C

[0114] D.2.5. Feathering

[0115] The ink was applied undiluted on the rough side of a Be.tex display 210FR supplied by Berger, Germany according to D.2.3. Feathering was evaluated according to Table 2.

[0116] Table 2

[0117] observe Score No / slight feathering A Medium Feather B Severe feathering C

[0118] D.2.6. Storage stability of ink

[0119] In order to evaluate the storage stability of the ink, the average particle size of the ink was first measured by dynamic light scattering on a diluted sample of the ink using a 4mW HeNe laser at a wavelength of 633nm by photon correlation spectroscopy. This was performed using a Nicomp380 available from Particle Size Solutions. Fresh samples and samples aged for 2 weeks in an oven at 60°C were measured. The relative change in average particle size (PS) was calculated as follows: [(PS (2 weeks 60°C) - PS (fresh)) / PS (fresh)] and scored according to Table 3.

[0120] Table 3

[0121] Relative change of PS (%) Score PS<10 A 10≤PS<20 B 20≤PS<30 C 30≤PS<40 D

[0122] D.3. Preparation of disperse dye dispersion

[0123] In all the following dispersion preparations, the amounts of compounds, solutions, emulsions are given in % by weight relative to the total weight of the dispersion.

[0124] Preparation of blue disperse dye dispersion (BDDD-1)

[0125] Use mechanical agitator to premix 48.73 wt % of deionized water, 25 wt % of Bykjet9170 and 0.4 wt % of biocide (Proxelk-D3798) in a container. First, 25 wt % of DB359 is sprayed in the solution, and then its pH value is increased by adding 0.873% of triethanolamine. The pre-dispersion obtained is mixed for 30 minutes. Fill the DynoMill-RL grinder to 42% with 0.4mm yttrium-stabilized zirconium oxide beads ("high wear-resistant zirconium oxide grinding media" from TOSOH Co.). The pre-dispersion is pumped into the bead mill and ground in a recirculation mode at a rotational speed of 11.8m / s. After a residence time of 30 minutes, the grinder is emptied by pumping the dispersion obtained into the container.

[0126] The blue disperse dye dispersion contained particles having an average particle size of 142 nm and a viscosity of 76 mPa·s.

[0127] Preparation of Blue Disperse Dye Dispersion (BDDD-2) Using Lignin Sulfonate

[0128] Use mechanical agitator to premix 42.73 wt % of deionized water, 25 wt % of Bykjet9170, 0.4 wt % of biocide (Proxelk-D3798) and 6 % of VANI in a container until all VANI is in solution. Then, 25 wt % of DB359 is sprayed in the solution, and then its pH value is increased by adding 0.873 % of triethanolamine. The obtained pre-dispersion is mixed for 30 minutes. Fill the DynoMill-RL grinder to 42% with 0.4 mm yttrium-stabilized zirconium oxide beads ("high wear-resistant zirconium oxide grinding media" from TOSOH Co.). The pre-dispersion is pumped into the bead mill and grinding is started in a recirculation mode at a rotation speed of 11.8 m / s. After a residence time of 30 minutes, the grinder is emptied by pumping the obtained dispersion into the container.

[0129] The blue disperse dye dispersion with VANI contained particles with an average particle size of 189 nm and a viscosity of 419 mPa.s.

[0130] Preparation of black disperse dye dispersion (BDDD-3)

[0131] Use mechanical agitator to premix 37.6 wt % of deionized water, 30 wt % of Disperbyk2010 and 0.4 wt % of biocide (Proxelk-D3798) in a container. Use the following order of addition to spray the following products one by one in the premix. First, add 12.64 wt % of DB 360, then add 12.64 wt % of DO 25, 3.23 wt % of DY54 and 3.49 wt % of DR 60. The obtained predispersion is mixed for 30 minutes. Fill the DynoMill-RL grinder to 42% with 0.4mm yttrium-stabilized zirconium oxide beads ("high wear-resistant zirconium oxide grinding media" from TOSOH Co.). The predispersion is pumped into the bead mill and grinding is started in a recirculation mode at a rotation speed of 11.8m / s. After a residence time of 25 minutes, the grinder is emptied by pumping the obtained dispersion into the container.

[0132] The black disperse dye dispersion contained particles with an average particle size of 133 nm and a viscosity of 254 mPa.s.

[0133] Preparation of black disperse dye dispersions (BDDD-4 to BDDD-7) using lignin sulfonates

[0134] Premix 5 wt% VANI as the first dispersant, 30 wt% Disperbyk 2010 or 30 wt% Disperbyk 190 or 12 wt% Rhodoline 3400 or 12 wt% Edaplan 482 as the second dispersant, deionized water (32.6 wt% when Disperbyk 2010 or Disperbyk 190 is used, 50.6 wt% when Rhodoline 3400 or Edaplan 482 is used) and 0.4 wt% biocide (Proxelk-D3798) in a container using a mechanical stirrer until all ingredients are dissolved. Spray the following products one by one in the premix using the following order of addition. First, add 9.875 wt% DB 360, followed by 9.875 wt% DO 25, 2.52 wt% DY54 and 2.73 wt.% DR 60. The obtained pre-dispersion was mixed for 30 minutes. A DynoMill-RL mill was filled to 42% with 0.4 mm yttrium-stabilized zirconia beads ("High Wear Resistant Zirconia Grinding Media" from TOSOH Co.). The pre-dispersion was pumped into the bead mill and grinding was started in recirculation mode at a rotation speed of 11.8 m / s. After a residence time of 25 minutes, the mill was emptied by pumping the obtained dispersion into a container.

[0135] The particle size and viscosity of the obtained dispersions are listed in Table 4.

[0136] Table 4

[0137] Dispersion Second dispersant Average particle size (nm) Viscosity (mPa.s) BDDD-4 Disperbyk 2010 119 101 BDDD-5 Edaplan 482 114 20 BDDD-6 Disperbyk 190 203 High viscosity BDDD-7 Rhodoline 3400 194 High viscosity

[0138] As can be seen from Table 4, the second dispersants based on polyacrylate or ethoxylated tristyrylphenyl exhibit much higher average particle size and viscosity than the second dispersants based on copolymers of acrylate and alkylene oxide. Even if these dispersions could be incorporated into the ink composition, this would certainly lead to jetting reliability issues and storage stability issues due to the increased average particle size.

[0139] Preparation of black disperse dye dispersion (BDDD-8) using Edaplan 482 as the second dispersant

[0140] The day before, a solution of 50 wt % of Edaplan 482 in deionized water was prepared by intense mixing overnight. A mechanical stirrer was used to premix 50.6 wt % of deionized water, 24 wt % of Edaplan 482 solution and 0.4 wt % of biocide (Proxelk-D3798) in a container. The following products were sprayed one by one in the premix using the following order of addition. First, 9.875 wt % of DB 360 was added, followed by 9.875 wt % of DO 25, 2.52 wt % of DY54 and 2.73 wt. % of DR 60. The predispersion obtained was mixed for 30 minutes. The DynoMill-RL mill was filled to 42 % with 0.4 mm yttrium-stabilized zirconium oxide beads ("high wear-resistant zirconium oxide grinding media" from TOSOH Co.). The predispersion was pumped into a bead mill and ground in a recirculation mode at a rotational speed of 11.8 m / s. After a residence time of 25 minutes, the mill was emptied by pumping the obtained dispersion into a container.

[0141] D.4. Ink formulation

[0142] The dispersion prepared in D.3 was used to formulate cyan inventive inks and comparative inks according to Table 5. The amounts in Table 5 are in weight % relative to the total mass of the ink.

[0143] INKCOMP-1 is a cyan ink without lignin sulfonate. INKINV-1 is the same as INKCOMP-1, but contains lignin sulfonate (VANI) added freely to the ink composition. In this case, the lignin sulfonate is first dissolved in water (25% solution), after which it can be added to the ink formulation. INKINV-2 has the same composition as INKINV-1, but the lignin sulfonate (VANI) is added via dispersion during grinding.

[0144] Table 5

[0145] Compound INKCOMP-1 INKINV-1 INKINV-2 GLY 16.0 16.0 16.0 PD 20.0 20.0 20.0 SURF 0.67 0.67 0.67 VANI 0 1.5 0 BDDD-1 24.0 24.0 0 BDDD-2 0 0 24.0 Deionized water To 100% margin Margin to 100% To 100% margin

[0146] The dispersion prepared in D.3. was used to formulate black inventive and comparative inks according to Table 6. When the lignin sulfonate was added freely, the lignin sulfonate was first dissolved in water (25% solution) before it could be added to the formulation.

[0147] INKCOMP-2 and INKINV-3 to INKINV-5 contain surfactants, the other black inks in Table 6 do not contain surfactants. INKCOMP-2, -3 and -4 do not contain lignin sulfonate. INKINV-3, -4 and -6 contain freely added lignin sulfonate. INKINV-5, -7 and -8 contain lignin sulfonate added via dispersion during the grinding step. When added via the grinding step, the lignin sulfonate content in the ink is lower than the freely added lignin sulfonate content. INKCOMP-4 and INKINV-8 use Edaplan 482 as the second dispersant, while the other inks use Disperbyk 2010 as the second dispersant.

[0148] Table 6

[0149]

[0150] D.5. Evaluation

[0151] The cyan and black inks prepared in §D.4. were evaluated as described in §D.2.

[0152] As can be seen from Table 7, both cyan inks with lignin sulfonate added via dispersion or freely added to the ink composition showed lower L values ​​of the ink coating and showed improved ink stability by reducing particle size growth. In addition, they also showed less feathering than the control ink.

[0153] Table 7

[0154]

[0155] As can be seen in Table 8, the black inks with lignin sulfonate added either via dispersion or freely added to the ink composition showed lower L values ​​for the coating and did show improved feathering. For those inks, the lignin sulfonate had limited effect on particle size. In this case, the presence of the surfactant had a greater effect on storage stability / particle size growth.

[0156] Table 8

[0157] L value Feathering INKCOMP-2 C C INKINV-3 A B INKINV-4 B B INKINV-5 B B INKCOMP-3 C C INKINV-6 A A INKINV-7 B A INKCOMP-4 C B INKINV-8 B A

Claims

1. An aqueous ink for textile printing, comprising disperse dyes, a first dispersant and a second dispersant, wherein the first dispersant is selected from alkali metal salts of aromatic sulfonic acids, alkali metal salts of aromatic sulfonic acid-formalin condensates, alkali metal salts of β-naphthalenesulfonic acid and alkali metal salts of β-naphthalenesulfonic acid-formalin condensates, and the second dispersant is a copolymer of acrylate and alkylene oxide. 2 . The aqueous ink according to claim 1 , wherein the alkylene oxide is ethylene glycol or propylene glycol.

3. Aqueous ink according to any one of the preceding claims, wherein the aromatic sulfonic acid is a lignin sulfonate.

4. Aqueous ink according to any one of the preceding claims, wherein the ink is a black ink and the disperse dye is a mixture of a blue disperse dye and at least one other disperse dye.

5. The aqueous ink according to claim 4, wherein the disperse dye is a mixture of DO 25 or DBr 27, DY54 and DB360.

6. The aqueous ink according to any one of the preceding claims, wherein the amount of the first dispersant is 1 to 5 wt% relative to the total weight of the ink.

7. Aqueous ink according to any one of the preceding claims, wherein the disperse dye is dispersed via a grinding or high pressure homogenisation step.

8. An aqueous ink according to any one of the preceding claims, wherein the second dispersant and the aromatic sulfonic acid are present during a grinding or high pressure homogenisation step in the preparation of a disperse dye dispersion.

9. The aqueous ink according to any one of the preceding claims, further comprising a water-soluble organic solvent.

10. Aqueous ink according to any one of the preceding claims, further comprising a surfactant based on acetylenic diols (alcohols).

11. An aqueous inkjet ink set, wherein at least one aqueous inkjet ink comprises a disperse dye, a first dispersant and a second dispersant, wherein the first dispersant is selected from an alkali metal salt of an aromatic sulfonic acid, an alkali metal salt of an aromatic sulfonic acid-formalin condensate, an alkali metal salt of β-naphthalenesulfonic acid and an alkali metal salt of β-naphthalenesulfonic acid-formalin condensate, and the second dispersant is a copolymer of an acrylate and an alkylene oxide.

12. The aqueous inkjet ink set according to claim 11, wherein at least one aqueous inkjet ink is a black ink, a cyan ink or a magenta ink.

13. An inkjet recording method comprising the following steps: a) jetting the aqueous inkjet ink according to claim 1 to claim 10 onto a fabric comprising hydrophobic fibers to obtain an image comprising disperse dyes; and b) applying heat to the fabric to fix the disperse dye to the hydrophobic fibers.

14. An inkjet recording method comprising the following steps: a) jetting the aqueous inkjet ink according to claim 1 to claim 10 onto a transfer medium to obtain an image containing disperse dyes; and b) contacting the transfer medium with a fabric comprising hydrophobic fibers; and c) applying heat to the transfer medium and / or the fabric to fix the disperse dye to the hydrophobic fibers of the fabric.

15. A method for preparing the aqueous inkjet ink according to any one of claims 1 to 10, comprising the following steps: a) preparing a disperse dye dispersion by applying high shear force or grinding to a mixture comprising water, a first dispersant selected from alkali metal salts of aromatic sulfonic acids, alkali metal salts of aromatic sulfonic acid-formalin condensates, alkali metal salts of β-naphthalenesulfonic acid and alkali metal salts of β-naphthalenesulfonic acid-formalin condensates, and a second dispersant and a disperse dye, wherein the second dispersant is a copolymer of an acrylate and an alkylene oxide; and b) adding water, a water-soluble organic solvent and a surfactant to the disperse dye dispersion of step a).

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