JP2018104589A - Inkjet printing ink and inkjet printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet printing ink that has proper pH stability and proper print dryability even when containing a vinyl sulfone reactive dye in high concentrations, and also has excellent printing stability and long-term storage stability, and an inkjet printing method using the same.SOLUTION: An inkjet printing ink contains a reactive dye containing a vinyl sulfone reactive dye, urea, a cyclic urea compound, and water and has a pH of 3-5.5.SELECTED DRAWING: None

Description

  The present invention relates to an inkjet printing ink and an inkjet printing method.

  Conventionally, screen printing or roller printing using a plate has been performed as a printing method. However, in these printings, since it is necessary to prepare a plate prior to dyeing, the production efficiency is low. In recent years, since it is not necessary to produce a plate and the production efficiency is high, so-called ink jet textile printing, in which an image is formed on a recording medium such as a fabric by an ink jet method, has been performed.

  In inkjet printing, fine ink droplets are ejected from an inkjet recording head and landed on a recording medium such as a cloth to form an image. Examples of the color material contained in the ink used in ink jet textile printing include acid dyes, disperse dyes, and reactive dyes. A reactive dye may be used for forming an image on a fabric mainly composed of cellulose.

  In recent years, with the increase in speed of ink jet textile printers, higher ink density is being demanded. In order to increase the concentration of the ink, it is effective to use a vinyl sulfone reactive dye having high solubility in water or a water-soluble organic solvent. However, vinylsulfone type reactive dyes generate acid during the process (reaction of formula (1) described later) in which sulfatoethylsulfone (SES) changes to vinylsulfone (VS) during storage. There was a problem that the pH stability was low. Further, an image formed using an ink containing a vinyl sulfone reactive dye has a problem that it easily retains water and a water-soluble organic solvent and is difficult to dry (the dryness of a printed matter is low).

  For example, Patent Document 1 discloses a water-based ink for ink-jet recording containing carbon black, urea, and a pyridine derivative (water-soluble organic solvent) as a method for improving the drying property of a printed matter. Thus, it is said that the drying property of a printed matter can be improved by using a pyridine derivative as a water-soluble organic solvent.

  As a method for stabilizing the pH, it is known to add urea. For example, Patent Document 2 discloses an inkjet ink for textile printing containing a monochlorotriazine reactive dye, urea, 2-imidazolidinone, and an organic buffer.

JP-A-11-228894 JP 2010-116566 A

However, when a large amount of urea is added to the ink containing the vinyl sulfone reactive dye, the amino group constituting the urea attacks the sulfatoethyl sulfone (SES) of the vinyl sulfone reactive dye, and the following formula (1) It is easy to proceed.
_{D-SO 2 -CH 2 CH 2} -O-SO 3 M (SES body)
_{→ D-SO 2 CH = CH} 2 (VS _{body) + HO-SO 3 M ···} (1)
As a result, the hydrolysis reaction (reaction of the following formula (2)) of the vinyl sulfone body (VS body) easily proceeds in competition with the reaction between the vinyl sulfone body (VS body) and the fabric.
D—SO ₂ CH═CH ₂ (VS form) + H ₂ O
_{→ D-SO 2 -CH 2 CH} 2 -OH (Hy body) (2)
As a result, the content ratio of the non-reactive hydroxyethylsulfone (Hy form) in the ink is increased, and the content of the reactive vinylsulfone (VS form) is decreased. In addition, there is a problem that the density tends to decrease and the print stability tends to decrease.

  Further, under acidic conditions, urea is easily altered (decomposed) and solidified, so that there is a problem that the ink tends to thicken under long-term storage and the long-term storage stability is likely to deteriorate.

  Patent Document 1 mainly relates to an ink containing a pigment and a direct dye, and Patent Document 2 mainly relates to an ink containing a monochlorotriazine type reactive dye, both of which contain a vinyl sulfone type reactive dye. There is no suggestion of a problem of deterioration in print stability (print stability due to hydrolysis reaction of vinyl sulfone (VS)), which is a problem with ink.

  The present invention has been made in view of the above circumstances, and has an appropriate pH stability and drying property of printed matter even when the vinylsulfone type reactive dye is contained at a high concentration, and has good print stability. Another object of the present invention is to provide an inkjet printing ink having long-term storage stability and an inkjet printing method using the same.

[1] An ink jet textile printing ink comprising a reactive dye containing a vinyl sulfone reactive dye, urea, a cyclic urea compound, and water, and having a pH of 3.0 to 5.5.
[2] The inkjet textile printing ink according to [1], wherein the cyclic urea compound is solid at room temperature.
[3] The inkjet textile printing ink according to [1] or [2], wherein the content of the reactive dye is 15 to 30% by mass with respect to the total mass of the ink.
[4] The inkjet textile printing ink according to any one of [1] to [3], wherein the total content of the urea and the cyclic urea compound is 8 to 20% by mass with respect to the total mass of the ink.
[5] The inkjet textile printing ink according to any one of [1] to [4], wherein the urea content is 2 to 10% by mass with respect to the total mass of the ink.
[6] The inkjet printing according to any one of [1] to [5], wherein the content ratio of the urea and the cyclic urea compound is urea: cyclic urea compound = 10: 90 to 50:50 (mass ratio). ink.
[7] The inkjet textile printing ink according to any one of [1] to [6], wherein the cyclic urea compound is ethylene urea.
[8] The vinyl sulfone reactive dye is C.I. I. The inkjet textile printing ink in any one of [1]-[7] containing Reactive Black 5.
[9] A step of forming an image on a fabric provided with a hydrophilic resin having a hydroxy group by discharging droplets of the inkjet textile printing ink according to any one of [1] to [8] from a recording head; And a step of fixing the image by heating the fabric on which the image is formed.
[10] The inkjet printing method according to [9], wherein the fabric includes cellulose fiber or protein fiber.

  According to the present invention, even if a vinylsulfone type reactive dye is contained at a high concentration, ink jet printing has an appropriate pH stability and a drying property of printed matter, and also has good printing stability and long-term storage stability. An ink and an inkjet printing method using the ink can be provided.

It is the partial schematic which shows an example of a structure of an inkjet textile printing apparatus.

  In the ink containing a vinyl sulfone type reactive dye, the present inventors have replaced a part of urea with a cyclic urea compound; that is, by combining urea with a cyclic urea compound, an appropriate pH stability and printed matter can be obtained. It has been found that the printing stability and long-term storage stability can be improved while having a drying property.

The reason for this is not clear, but is considered as follows. That is, since the cyclic urea compound does not have a highly basic amino group, it does not promote the formation reaction (reaction of the above formula (1)) of the vinyl sulfone form (VS form). The hydrolysis reaction of the sulfone body (VS body) (the reaction of the above formula (2)) is not accelerated. As a result, it is possible to suppress an excessive increase in the non-reactive hydroxyethylsulfone (Hy) in the ink, so it is easy to reduce variations in image color and density (easily improve print stability). .
Furthermore, since cyclic urea compounds are unlikely to be altered (decomposed) even under acidic conditions, the ink is less likely to thicken even under long-term storage, and long-term storage stability is unlikely to be impaired.
Therefore, even if the ink contains a vinyl sulfone reactive dye at a relatively high concentration, the print stability and long-term storage stability can be enhanced while having an appropriate pH stability.

  Further, by using a cyclic urea compound that is solid at room temperature, the content ratio of the liquid component (water or water-soluble organic solvent) in the ink can be relatively reduced. Thereby, even if it is an ink containing a vinyl sulfone type reactive dye, the dryness of a printed matter can be improved. The present invention has been made based on these findings.

1. Inkjet Textile Ink The inkjet textile ink of the present invention contains a reactive dye, urea, a cyclic urea compound, and water. The inkjet textile printing ink of the present invention may further contain a water-soluble organic solvent, other additives, and the like as necessary.

(Reactive dye)
The reactive dye contained in the inkjet textile printing ink of the present invention includes a reactive dye having a vinyl sulfone group (hereinafter also referred to as “vinyl sulfone type reactive dye”). The vinyl sulfone reactive dye has a monochlorotriazine group and is more soluble in water and water-soluble organic solvents than a reactive dye that does not have a vinyl sulfone group (hereinafter also referred to as “monochlorotriazine reactive dye”). Therefore, not only is it easy to increase the concentration of the reactive dye in the ink, but it also has high dyeing properties.

The vinyl sulfone type reactive dye reacts as follows in the presence of alkali.
_{D-SO 2 -CH 2 CH 2} -O-SO 3 M
_{→ D-SO 2 CH = CH} 2 + HO-SO 3 M ... (1)

  D in the formula (1) represents a dye matrix. Examples of the dye matrix include pyrazolone azo series, gamma acid azo series, H acid azo series, anthraquinone series, and H acid disazo series. M represents a monovalent metal cation. Examples of monovalent metal cations include Na ions.

  In the vinyl sulfone type reactive dye, the vinyl group of the vinyl sulfone type reactive dye undergoes a nucleophilic addition reaction to the hydroxyl group of the fabric and reacts with the fabric.

  The vinyl sulfone type reactive dye has one or more vinyl sulfone groups. The vinyl sulfone-type reactive dye may have two or more functional groups that react with the fabric from the viewpoint of enhancing the dyeability to the fabric, but one or more of the two or more functional groups may be vinyl sulfone groups. That's fine. Reactive dyes in which one or more of two or more functional groups are vinyl sulfone groups include reactive dyes having two vinyl sulfone groups in one molecule (hereinafter also referred to as “vinyl sulfone type homobifunctional reactive dyes”) and A reactive dye having one vinyl sulfone group and one monochlorotriazine group in one molecule (hereinafter also referred to as “heterobifunctional reactive dye”) is included. The vinyl sulfone type reactive dye used in the present invention is preferably a vinyl sulfone type homobifunctional reactive dye from the viewpoint of further improving the dyeability on the fabric.

  When a heterobifunctional reactive dye is used as the vinyl sulfone reactive dye, the reaction between the reactive dye and the fabric can cause not only the above nucleophilic addition reaction but also a nucleophilic substitution reaction. This is caused by nucleophilic substitution reaction of the chloro group of the monochloro-substituted 1,3,5-triazin-2-yl skeleton possessed by the heterobifunctional reactive dye with the hydroxyl group of the fabric.

  Examples of the vinyl sulfone type reactive dye include C.I. I. Reactive Yellow 15, C.I. I. Reactive Yellow 37, C.I. I. Reactive yellow 42; I. Reactive Orange 16, C.I. I. Reactive Orange 78, C.I. I. Reactive Orange 107; C.I. I. Reactive Red 23, C.I. I. Reactive Red 35, C.I. I. Reactive Red 106, C.I. I. Reactive Red 180; C.I. I. Reactive Violet 5, C.I. I. Reactive Blue 19, C.I. I. Reactive Blue 21, C.I. I. Reactive Blue 38, C.I. I. Reactive blue 229; I. Reactive brown 18; C.I. I. Reactive Black 5, C.I. I. Reactive Black 14, C.I. I. Reactive black 31 and the like are included. Among these, C.I. is a vinyl sulfone type homobifunctional reactive dye. I. Reactive black 5 is preferred.

  The reactive dye contained in the inkjet textile printing ink of the present invention may further contain a reactive dye other than the vinyl sulfone type reactive dye. Examples of other reactive dyes include monochlorotriazine type reactive dyes.

  The content of the reactive dye is preferably 15 to 30% by mass with respect to the total mass of the ink. If the reactive dye content is 15% by mass or more with respect to the total mass of the ink, the concentration of the ink is easily increased, and if it is 30% by mass or less, the ink is difficult to thicken, and the injection stability is impaired. Hateful. The content of the reactive dye is more preferably 20 to 30% by mass with respect to the total mass of the ink.

  The content of the vinyl sulfone reactive dye is preferably 50% by mass or more based on the total mass of the reactive dye. When the content of the vinyl sulfone type reactive dye is 50% by mass or more with respect to the total mass of the reactive dye, high dyeing properties are easily obtained. The content of the vinyl sulfone type reactive dye is more preferably 70% by mass or more, and may be 100% by mass with respect to the total mass of the reactive dye.

(urea)
Urea can maintain the pH of the ink within a predetermined range and can make it difficult for the water in the ink to volatilize on the nozzle surface, thereby improving the ejection stability.

  The urea content is preferably 2 to 10% by mass with respect to the total mass of the ink. When the urea content is 2% by mass or more, it is easy to stabilize the pH of the ink. When the urea content is 10% by mass or less, excessive hydrolysis reaction of the vinyl sulfone (VS) can be suppressed. Therefore, the print stability is not easily lost. In addition, since the ink does not thicken due to the decomposition of urea under long-term storage, long-term storage stability is not easily impaired. Furthermore, since the content ratio of the solid component in the ink is not relatively increased, the ink is difficult to thicken and the ejection stability is not easily impaired. The urea content is more preferably 5 to 8% by mass with respect to the total mass of the ink.

  The urea content is preferably 5 to 50 mass%, more preferably 15 to 40 mass%, based on the total mass of the reactive dye.

(Cyclic urea compound)
The cyclic urea compound makes it difficult for water in the ink to volatilize on the nozzle surface, and can improve ejection stability. The cyclic urea compound is a cyclic urea compound having no amino group adjacent to the carbonyl carbon in the molecule. Examples of the cyclic urea compound include ethylene urea, propylene urea, dimethylethylene urea and the like.

  The cyclic urea compound may be solid at normal temperature or liquid at normal temperature. The cyclic urea compound is preferably solid at room temperature, more preferably ethylene urea, from the viewpoint of easily improving the drying property and injection stability of the printed matter.

  The total content of urea and the cyclic urea compound is preferably 8 to 20% by mass with respect to the total mass of the ink. When the total content of urea and the cyclic urea compound is 8% by mass or more, it is easy to prevent drying of the ink itself, and thus it is easy to improve ejection stability. Further, since the content ratio of the liquid component in the ink can be relatively reduced, it is easy to improve the drying property of the printed matter. When the total content of urea and the cyclic urea compound is 20% by mass or less, the content ratio of the solid component in the ink is not relatively increased, so that the ink is difficult to thicken and the ejection stability is not easily impaired. The total content of urea and the cyclic urea compound is more preferably 8 to 20% by mass with respect to the total mass of the ink.

  The total content of urea and the cyclic urea compound is preferably 10 to 100% by mass and more preferably 50 to 100% by mass with respect to the total mass of the reactive dye.

  The content of the cyclic urea compound is preferably the same as or higher than the content of urea. This is because the printing stability is easily obtained without excessively promoting the hydrolysis of the vinyl sulfone (VS). Specifically, the content ratio of urea and the cyclic urea compound is preferably urea: cyclic urea compound = 10: 90 to 50:50 (mass ratio). When the content ratio of urea and the cyclic urea compound is within the above range, the pH of the ink is stabilized to some extent, but the hydrolysis reaction of the vinyl sulfone (VS) is not promoted too much, so that the printing stability is improved. Cheap. In addition, since it is easy to suppress ink thickening due to decomposition of urea under long-term storage, long-term storage stability is not easily impaired. The content ratio of urea and the cyclic urea compound is more preferably urea: cyclic urea compound = 20: 80 to 50:50 (mass ratio).

(Water-soluble organic solvent)
Each of the inkjet textile printing inks of the present invention may contain a water-soluble organic solvent. The water-soluble organic solvent is not particularly limited as long as it can dissolve the reactive dye.
Examples of water-soluble organic solvents that may be used in the present invention include
Alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, t-butanol);
Polyhydric alcohols (for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol);
Amines (e.g., ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyl Diethylenetriamine, tetramethylpropylenediamine);
Amides (eg, N, N-dimethylformamide, N, N-dimethylacetamide, etc.);
Heterocycles (eg, 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexylpyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, etc.);
Sulfoxides (for example, dimethyl sulfoxide) and the like are included.

(Other additives)
The inkjet textile printing ink of the present invention may further contain other additives such as a surfactant, an antiseptic, an antifungal agent, and a pH adjuster.

[Surfactant]
Examples of surfactants that may be used in the present invention include dialkyl sulfosuccinates, alkyl naphthalene sulfonates, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene poly Oxypropylene block copolymers, alkylamine salts, quaternary ammonium salts, silicon surfactants, fluorine surfactants and the like are included. Among these, acetylene glycol surfactants have relatively low foaming properties and can adjust the surface tension of the ink. For this reason, the ink ejectability from the ink jet recording head is enhanced.

[Preservatives, antifungal agents]
Examples of preservatives and antifungal agents that may be used in the present invention include aromatic halogen compounds (for example, Preventol CMK), methylene dithiocyanate, halogen-containing nitrogen-sulfur compounds, 1,2-benzisothiazolin-3-one. (For example, PROXEL GXL) and the like are included. Preservatives and antifungal agents increase the storage stability of the ink.

[PH adjuster]
An example of a pH adjuster that may be used in the present invention may be sodium hydroxide.

(Ink physical properties)
The pH of the inkjet textile printing ink of the present invention preferably satisfies the range of 3.0 to 5.5. When the pH is within the above range, not only the above-described vinyl sulfone reactive dye is likely to exist stably, but also corrosion of the nozzle can be suppressed. The pH of the ink can be measured at 25 ° C. using a HM-20S type manufactured by Toa DKK Corporation.

  The ink jet textile ink of the present invention preferably has an ink viscosity at 25 ° C. of 1 to 100 mPa · s, more preferably 1 to 40 mPa · s, from the viewpoint of ejection properties from the ink jet recording head. More preferably, it is 40 mPa * s, and it is especially preferable that it is 5-20 mPa * s. The viscosity of the ink can be measured with a cone plate viscometer, for example, a TVE-33LT viscometer manufactured by Toki Sangyo Co., Ltd.

  The surface tension of the ink at 25 ° C. is preferably 30 to 60 mN / m. If the surface tension of the ink is 30 mN / m or more, the wettability of the ink with respect to the fabric does not become too high, and it is easy to suppress bleeding of the image. On the other hand, when the surface tension is 60 mN / m or less, the wettability of the ink with respect to the fabric is not too low, so that the ink penetration force is not easily impaired.

(Preparation of ink)
The ink-jet printing ink of the present invention is produced through a step of mixing the above-mentioned reactive dye, urea, a cyclic urea compound, water, and other components as required.

2. Inkjet Textile Printing Method The inkjet textile printing method using the inkjet textile printing ink of the present invention forms an image on a fabric provided with a hydrophilic resin having a hydroxy group by discharging droplets of the inkjet textile printing ink of the present invention from a recording head. And a step of heating the fabric on which the image is formed to fix the image on the fabric. A fabric provided with a hydrophilic resin having a hydroxy group can be obtained by applying a pretreatment agent containing a hydrophilic resin having a hydroxy group to the fabric.

  That is, the inkjet printing method of the present invention includes (1) a step of applying a pretreatment agent containing a hydrophilic resin having a hydroxy group (pretreatment step) and (2) a fabric provided with the pretreatment agent. A step of forming an image by ejecting droplets of textile printing ink (ink applying step), and (3) a step of heating the fabric on which the image is formed and fixing the image on the fabric (coloring step). If necessary, (4) a step of drying the fabric after application of ink (preliminary drying step), (5) a step of removing dyes and pretreatment agents that could not be dyed on the fabric (washing step), ( 6) A step of drying the washed fabric (drying step) may be further included.

(Pretreatment process)
The pretreatment step is a step of applying a pretreatment agent to the fabric. Examples of the method for applying the pretreatment agent to the fabric include a pad method, a coating method, a spray method, and an ink jet method. By these methods, the pretreatment agent can be applied onto the fabric. Examples of fabrics to which a pretreatment agent has been added include fabrics having an ink receiving layer described in JP-A No. 62-53492, and anti-reduction agents and alkaline agents described in JP-B-3-46589. Included fabrics and the like are included.

  From the viewpoint of obtaining a uniform image, before applying the pretreatment agent to the fabric, natural impurities (oils, waxes, pectic substances, natural pigments, etc.) adhering to the fabric fibers, and residues of the chemicals used in the fabric manufacturing process ( It is preferable to clean the adhesive or the like) or the dirt attached to the fabric. The cleaning agent for cleaning the fabric includes an alkali agent such as sodium hydroxide or sodium carbonate, an anionic or nonionic surfactant, or an enzyme.

  The pretreatment agent preferably contains at least a resin component, an alkali agent, and a hydrotropic agent, and may further contain additives such as a reduction inhibitor, a preservative, or a chelating agent.

  The resin component preferably contains a hydrophilic resin having a hydroxy group. Examples of hydrophilic resins having a hydroxy group include natural gums such as guar and locust bean, starches, seaweeds such as sodium alginate and funari, plant skins such as pectic acid, methyl fibrin, ethyl fibrin, hydroxy Fibrin derivatives such as ethyl cellulose and carboxymethyl cellulose, processed starches such as roasted starch, alpha starch, carboxymethyl starch, carboxyethyl starch and hydroxyethyl starch, processed natural gums such as shiraz gum and roast bean gum, algin derivatives and poly Synthetic pastes such as vinyl alcohol and polyacrylic acid esters, and emulsions are included.

  Examples of alkaline agents include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, amines such as mono, di, and triethanolamine, and carbonates such as sodium carbonate, potassium carbonate, and sodium bicarbonate (sodium bicarbonate). Alternatively, alkali metal bicarbonates, organic acid metal salts such as calcium acetate and barium acetate, ammonia and ammonia compounds, sodium trichloroacetate which becomes an alkali agent under steaming or dry heat, and the like are included. Among these, sodium carbonate and sodium hydrogen carbonate are preferable. The amount of the alkaline agent applied is preferably 0.1 to 10% by mass and more preferably 0.5 to 5% by mass with respect to the total mass of the fabric. The presence of an appropriate alkaline agent in the fabric allows the printing ink containing the reactive dye to be reliably dyed. Therefore, it is preferable that the fabric contains an alkali agent in advance.

  Examples of the hydrotropic agent include urea, ethyleneurea, dimethylurea, thiourea, monomethylthiourea, alkylurea such as dimethylthiourea, and the like. This is because the image density is improved by the addition of the hydrotropic agent.

  The application amount (squeezing ratio) of the pretreatment agent or the amount of the resin component contained in the pretreatment agent is appropriately set according to the type of fabric and its use.

  The pretreatment agent may further contain a reduction inhibitor, a preservative, or a chelating agent as necessary. The reduction inhibitor may be sodium m-nitrobenzenesulfonate or the like. The preservative may be the preservative exemplified as the preservative for printing ink, or may be the same. The chelating agent may be ethylenediaminetetraacetate, nitrilotriacetate, hexametaphosphate, pyrophosphate, or metaphosphate.

  The pretreatment agent applied to the fabric can be heat-dried using hot air, a hot plate, a heat roller, or the like.

  The fiber material constituting the fabric is not particularly limited as long as a hydrophilic resin having a hydroxy group is provided (as a pretreatment agent), but in terms of enhancing dyeability, a fiber that can be dyed with a reactive dye; It is preferable to include a fiber having a hydroxy group. Examples of the fiber having a hydroxy group include cellulose fibers such as cotton and protein fibers such as silk. The fabric may be any form of these fibers such as a woven fabric, a nonwoven fabric, and a knitted fabric. The fabric that can be used in the present invention may be composed only of fibers that can be dyed with reactive dyes, but may be a blended woven fabric or a blended nonwoven fabric with rayon, polyurethane, polyester, acrylic, or the like. . Moreover, it is preferable that the thickness of the fiber which comprises a fabric exists in the range of 10-100d.

(Ink application process)
The ink application step is a step of forming a pre-colored image by discharging ink-jet textile ink droplets from the ink-jet recording head toward the fabric. While moving the cloth relative to a head carriage on which a plurality of ink jet recording heads are mounted, droplets of the ink jet printing ink set are discharged and landed on the cloth. The surface temperature of the fabric when the ink droplets land is not particularly limited, but it is preferably heated in the range of 35 to 70 ° C. from the viewpoint of suppressing bleeding of the pre-colored image. Note that it is preferable to keep the ink temperature at 25 ° C. from the viewpoint of suppressing fluctuations in ink viscosity due to fluctuations in ink temperature.

(Preliminary drying process)
The preliminary drying step is a step of drying the fabric after ink application. Although not particularly limited, the preliminary drying is preferably performed by drying the fabric at 150 ° C. or lower for 0.5 to 30 minutes. Examples of the drying method include an air convection method, a heating roll direct attachment method, and an irradiation method. Specifically, ink may be applied to the fabric, and the fabric may be dried under the above conditions and method before the fabric is wound.

(Coloring process)
The color development step refers to heating the fabric after ink application (after predrying when it includes a predrying step) to dye reactive dyes that are not sufficiently dyed into the fabric, This is a step of developing a hue.

  Although the color development temperature (heating temperature) depends on the color development method (heating method), it is preferably 95 ° C. or higher and lower than 220 ° C., and 95 ° C. or higher and 190 ° C. or higher from the viewpoint of strengthening the dyeing of the reactive dye onto the fabric. More preferably, it is 100 degrees C or less, and it is still more preferable that it is 100 degreeC or more and 180 degrees C or less.

  The color development method (heating method) may be a conventionally known method, and is appropriately selected depending on textile printing ink, fabric, or the like. For example, steaming; baking with dry heat; thermosol; HT steamer with superheated steam. Among these, a method (steaming method) and a dry heat method (baking method) in which reactive dyes in the ink are fixed by high-heat steam are preferable.

  In the steaming method using high-temperature steam, if the heating temperature is too low, a large amount of liquid water exists, so reactive dyes contained in dark ink and light color ink are likely to hydrogen bond with liquid water in addition to fabrics. For this reason, it may be easily washed away with water and may not be sufficiently dyed. Therefore, from the viewpoint of strengthening the dyeing of the reactive dye onto the fabric, the heating temperature is preferably 95 ° C. or higher, and more preferably 100 ° C. or higher. For example, cellulosic fibers are preferably treated at 95-105 ° C. for 5-15 minutes; amide fibers such as silk and wool are preferably treated at 95-105 ° C. for 20-40 minutes. . In addition, the fabric to which the ink has been applied may be colored immediately or after a lapse of time.

  In the baking method by dry heat, from the viewpoint of easily obtaining sufficient dyeability and easily suppressing the decomposition of the dye, the heating temperature is preferably 150 ° C. or higher and lower than 220 ° C., 150 ° C. or higher and 190 ° C. Or less, more preferably 150 ° C. or more and 180 ° C. or less.

(Washing process)
The washing step is a step of removing reactive dyes and pretreatment agents that could not be dyed on the fabric after the color development step of the fabric. The removal of reactive dyes that could not be dyed on the fabric can be performed by a conventionally known cleaning method, and is appropriately selected depending on the printing ink, the fabric, or the like. For example, the cellulose fiber is generally washed with hot water and water after being treated with a soaping bath containing a nonionic detergent after washing with water and hot water. By removing the undyed reactive dye, the fastness to washing, the fastness to water, the fastness to sweat, and the like tend to be improved. If there is a reactive dye that could not be dyed on the fabric, it is difficult to obtain fastness to washing, fastness to water, fastness to sweat, and the like.

(Drying process)
A drying process is a process performed after the said washing | cleaning process and drying the wash | cleaned fabric. The drying method is not particularly limited, and may be a method of squeezing the washed fabric, drying it, or drying it using a dryer (heat roll, iron, etc.).

(Inkjet printing device)
Hereinafter, an apparatus for performing the ink application process and the preliminary drying process will be described with reference to the drawings. However, the inkjet printing apparatus is not limited thereto.

  FIG. 1 is a partial schematic diagram illustrating an example of the configuration of an inkjet textile printing apparatus. The ink jet textile printing apparatus includes a transport means 2 for transporting the cloth P, a head carriage 5 on which a plurality of ink jet recording heads (not shown) for ejecting ink jet textile ink droplets are mounted on the cloth P, and warm air on the cloth P. And hot air applying means 6 for applying.

  The transport unit 2 includes an adhesive belt 21, a support roller 22, a transport roller 23, and a nip roller 24. The adhesive belt 21 is held by the support roller 22 and the conveyance roller 23 and circulates between the support roller 22 and the conveyance roller 23. The nip roller 24 is disposed to face the conveying roller 23 with the adhesive belt 21 interposed therebetween.

  The warm air applying means 6 and the head carriage 5 are disposed above the fabric P. The warm air applying means 6 includes a fan 6A that blows wind on the fabric and a heating element 6B that can control the temperature. On the other hand, the head carriage 5 includes an ink jet recording head. The type of the ink jet recording head is not particularly limited, and may be either a thermal type or a piezo type. The nozzle diameter of the ink jet recording head is preferably 10 to 100 μm, and more preferably 10 to 50 μm. This is because if the nozzle diameter is 10 μm or more, nozzle clogging due to insoluble matter is unlikely to occur, and if it is 100 μm or less, the sharpness of the formed image is difficult to be lowered. Further, the droplet size of the ink to be ejected is preferably 4 to 150 pl, and more preferably 5 to 80 pl. This is because when the ink droplet size is 4 pl or more, the ejected ink droplets are not easily affected by the air flow in the vicinity of the head, and when the ink droplet size is 150 pl or less, the granularity of the formed image is not noticeable.

  When the transport roller 23 is driven, the fabric P disposed on the upper surface of the adhesive belt 21 is transported to the lower surface of the nip roller 24. The fabric P is pressed by the adhesive belt 21 and the nip roller 24 and fixed to the adhesive belt 21. The fabric P fixed to the adhesive belt 21 is conveyed below the head carriage 5. A plurality of ink jet recording heads mounted on the head carriage 5 ejects ink jet printing ink droplets, land on a predetermined region (landing possible region) of the fabric to which the pretreatment agent is applied, and form an image. Next, the temperature-controlled wind or warm air is blown from the warm air applying means 6 to dry the image formed on the fabric P.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

1. Ink material (Reactive dye)
VS dye: C.I. I. Reactive Black 5 (see formula below)

(Cyclic urea compound)
Ethylene urea (solid at room temperature)
Propylene urea (liquid at room temperature)
Dimethyl ethylene urea (liquid at room temperature)

(Water-soluble organic solvent)
Glycerin Ethylene glycol Propylene glycol

(Other ingredients)
Surfactant (E1010 manufactured by Nissin Chemical Industry Co., Ltd.)
Preservative (Lonza Japan Proxel GXL (S))

2. Ink Preparation and Evaluation (Example 1)
As a vinyl sulfone type reactive dye, C.I. I. 15 parts by mass of Reactive Black 5; 2.0 parts by mass of urea; 3.0 parts by mass of ethylene urea as a cyclic urea compound; 5 parts by mass of glycerin as a water-soluble organic solvent, 20 parts by mass of ethylene glycol, propylene glycol 10 parts by mass; 0.5 parts by mass of E1010 as a surfactant; 1 part by mass of Proxel GXL (S) as a preservative was mixed. Ion exchanged water was added to the resulting mixture so that the total amount was 100 parts by mass to prepare an ink.

(Examples 2 to 10 and Comparative Examples 1 to 4)
An ink was prepared in the same manner as in Example 1 except that the composition of the ink was changed to the composition shown in Table 1 or 2.

  The pH and long-term storage stability (pH stability, viscosity stability) of the obtained ink were evaluated by the following methods.

(PH, pH stability)
The pH of the obtained ink at 25 ° C. was measured using HM-20S type manufactured by Toa DKK Corporation. After the ink was stored at 25 ° C. for 4 weeks, the pH of the ink was measured in the same manner. The ink pH change ΔpH before and after storage (= ink pH before storage−ink pH after storage) was calculated and evaluated based on the following criteria.
A: ΔpH is ± 0.2 or less ○: ΔpH is more than ± 0.2 ± 0.3 or less ○ Δ: ΔpH is more than ± 0.3 ± 0.5 or less Δ: ΔpH is more than ± 0.5 ± 1. 0 or less x: ΔpH exceeds ± 1.0 It was judged that the pH of the ink was in the range of 3 to 5.5.
If the pH stability of the ink was Δ or more, it was judged to be satisfactory because it was a practically satisfactory level.

(Viscosity stability)
The viscosity of the obtained ink was measured at 25 ° C. with a TVE-33LT viscometer manufactured by Toki Sangyo Co., Ltd. After the ink was stored at 25 ° C. for 4 weeks, the viscosity of the ink was measured by the same method. The change in the viscosity of the ink before and after storage (= viscosity of ink before storage−viscosity of ink after storage) was calculated and evaluated based on the following criteria.
A: Viscosity change is ± 0.4 mPa · s or less ○: Viscosity change is more than ± 0.4 mPa · s ± 0.5 mPa · s or less ○ △: Viscosity change is more than ± 0.5 mPa · s 1.0 mPa・ S or less Δ: Viscosity change amount is more than 1.0 mPa · s 2.0 mPa · s or less ×: Viscosity change amount is more than 2.0 mPa · s or solidified and cannot be measured. The level was satisfactory and judged to be good.

  Furthermore, using the obtained ink, an image was formed by the inkjet printing method according to the following procedure.

<Inkjet printing method>
(Pretreatment process)
A 100% cotton fabric (with cotton broad sill, manufactured by Color & Color Co., Ltd.) was prepared, and the following pretreatment agent was applied at a drawing rate of 80% and then dried.
(Pretreatment agent)
Sodium alginate (resin component): 5 parts by weight Urea (hydrotropic agent): 10 parts by weight Sodium hydrogen carbonate (alkali agent): 5 parts by weight Ion exchange water: 80 parts by weight

(Ink application process)
The obtained ink was set in Nassenger V (manufactured by Konica Minolta). A solid image was formed using the obtained ink at main scanning 540 dpi × sub-scanning 540 dpi. In addition, dpi represents the number of ink droplets (dots) per 2.54 cm.

(Coloring process)
The fabric on which the image was formed was steam-treated for 8 minutes under the conditions of a relative humidity of 100% and a temperature of 103 ° C. to fix and develop the dye.

<Image evaluation>
Then, print stability, injection stability, and dryness of the printed material were evaluated by the following methods, respectively.

(Print stability)
The obtained ink was stored at 50 ° C. for 4 weeks, and then image formation was performed under the same conditions as described above. The color values (L *, a *, b *) of the solid image formed using the ink before storage and the solid image formed using the ink after storage are respectively measured using the colorimeter X-Rite 938. It was measured. Then, the color specification values (L ₁ *, a ₁ *, b ₁ *) of the ink before storage and the color specification values (L ₂ *, a ₂ *, b ₂ *) of the ink after storage are expressed by the following equations. By applying, ΔE was calculated.
ΔE = [(L ₂ ^* −L ₁ ^* ) ² + (a ₂ ^* −a ₁ ^* ) ² + (b ₂ ^* −b ₁ ^* ) ² ] ^1/2
The print stability was evaluated based on the following criteria.
A: ΔE <0.5
○: 0.5 ≦ ΔE <1.0
○ △: 1.0 ≦ ΔE <1.5
Δ: 1.5 ≦ ΔE <2.0
×: 2.0 ≦ ΔE
If it was more than (triangle | delta), it was a level which is satisfactory practically and was judged favorable.

(Injection stability)
The ink from the inkjet head was ejected for a certain time at 25 ° C. and 50% RH. Thereafter, the ink was allowed to stand for 30 minutes, and the ink was ejected again. The ejectability at that time was observed with a drop watcher. And the reinjection property after leaving for 30 minutes was evaluated based on the following criteria.
◎: Less than 200 shots can be re-injected with no defects by discarding (refreshing the ink on the nozzle surface by discarding) ○: More than 200 shots can be re-injected with no more than 500 shots △: Can be re-injected without defects by discharging more than 500 shots and 1000 or less ×: Cannot be handled by discharging, and maintenance (manual cleaning of the nozzle surface) is required. It was judged that it was good.

(Dryness of printed matter)
The printed matter on which the solid image was formed was dried at 80 ° C. for 1 minute (after the preliminary drying step), and then visually observed for the presence or absence of color transfer when the cloths were stacked. And it evaluated based on the following references | standards.
◎: No color transfer at all ○: Color transfer is slightly observed △: Color transfer is slightly recognized, but there is no problem in practical use ×: Level at which color transfer is recognized remarkably and becomes a problem in practical use △ or more In other words, it was judged to be satisfactory because the level was practically acceptable.

The evaluation results of the inks of Examples 1 to 10 are shown in Table 1; the evaluation results of the inks of Comparative Examples 1 to 4 are shown in Table 2. In the table, Gly represents glycerin, EG represents ethylene glycol, and PG represents propylene glycol. Moreover, the unit of the numerical value of the composition in a table | surface shall be a mass part.

  As shown in Table 1, the inks of Examples 1 to 10 have a good print stability while having an appropriate pH stability and a dryness of the printed matter even though they contain a vinyl sulfone type reactive dye. And long-term storage stability.

  In particular, it can be seen that increasing the urea content increases the pH stability and the dryness of the printed matter (comparison of the inks of Examples 3 and 10). However, it can be seen that when the urea content is too high, the hydrolysis reaction of the vinyl sulfone (VS) is likely to be accelerated, the print stability is slightly lowered, and the long-term storage stability is also slightly lowered (in the examples). Ink 4 and 10 contrast).

  Moreover, since the content ratio of the liquid component in the ink can be reduced by setting the total content of urea and the cyclic urea compound to 8% by mass or more, the drying property of the printed matter can be improved (Example 3, 4 to 7 and 10), by setting it to 20% by mass or less, it can be seen that the viscosity of the ink does not increase excessively and the ejection stability is hardly impaired (contrast of Examples 6 and 7).

  In addition, it can be seen that by increasing the content of the cyclic urea compound to be higher than the content of urea, the excessive hydrolysis reaction of the vinyl sulfone (VS) is suppressed, so that the printing stability is improved (Example) 5 and 6 ink contrast).

  It can also be seen that when the cyclic urea compound is ethylene urea that is solid at room temperature, it is easy to improve the drying property and the injection stability of the printed matter (contrast with Examples 8 to 10).

  On the other hand, as shown in Table 2, it can be seen that the inks of Comparative Examples 1, 2, and 4 have low ejection stability. This is presumably because the ink does not contain a cyclic urea compound, so the moisture retention of the ink is low, and the water contained in the ink evaporates near the nozzle and is easily dried. Furthermore, it can be seen that the ink of Comparative Example 4 has low print stability and long-term stability. The reason why the print stability was lowered is that urea is likely to promote the formation reaction of vinyl sulfone (VS), and accordingly, the hydrolysis reaction of vinyl sulfone (VS) is also facilitated. It is done. The reason why the long-term stability has decreased is considered to be that the urea has deteriorated (decomposed) during storage and the viscosity of the ink has increased.

  On the other hand, since the ink of Comparative Example 3 does not contain urea, it can be seen that the pH is low and the pH stability is also low.

  Ink-jet printing ink having moderate pH stability and drying property of printed matter even when vinylsulfone type reactive dye is contained at a high concentration, and having good printing stability and long-term storage stability, and The used ink jet printing method can be provided.

P Fabric 2 Conveying means 21 Adhesive belt 22 Support roller 23 Conveying roller 24 Nip roller 5 Head carriage 6 Warm air applying means 6A Fan 6B Heating element

Claims (10)

  An inkjet printing ink comprising a reactive dye containing a vinylsulfone type reactive dye, urea, a cyclic urea compound, and water, and having a pH of 3.0 to 5.5.   The inkjet printing ink according to claim 1, wherein the cyclic urea compound is solid at room temperature.   The inkjet textile printing ink according to claim 1 or 2 whose content of said reactive dye is 15-30 mass% to the total mass of ink.   The inkjet printing ink according to any one of claims 1 to 3, wherein a total content of the urea and the cyclic urea compound is 8 to 20% by mass with respect to a total mass of the ink.   The inkjet textile printing ink according to any one of claims 1 to 4 whose content of said urea is 2-10 mass% to the total mass of ink.   6. The ink-jet printing ink according to claim 1, wherein the content ratio of the urea and the cyclic urea compound is urea: cyclic urea compound = 10: 90 to 50:50 (mass ratio).   The inkjet textile printing ink as described in any one of Claims 1-6 whose said cyclic urea compound is ethylene urea.   The vinyl sulfone type reactive dye is C.I. I. The ink-jet textile printing ink according to any one of claims 1 to 7, comprising Reactive Black 5. A step of ejecting the droplets of the ink-jet printing ink according to any one of claims 1 to 8 from a recording head to form an image on a fabric provided with a hydrophilic resin having a hydroxy group;
And a step of fixing the image by heating the fabric on which the image is formed.   The ink-jet printing method according to claim 9, wherein the fabric includes cellulose fiber or protein fiber.

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