JP6809214B2 - Ink-printing ink and inkjet printing method - Google Patents

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, but in these printings, it is necessary to prepare a plate prior to dyeing, so that 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 inkjet printing, in which an image is formed on a recording medium such as a cloth by an inkjet method, has been performed.

In inkjet printing, minute droplets of ink are ejected from an inkjet recording head and landed on a recording medium such as a cloth to form an image. Types of coloring materials contained in inks used in inkjet printing include acid dyes, disperse dyes, and reactive dyes. Reactive dyes may be used to form images on fabrics containing cellulose as the main component.

In recent years, as the speed of inkjet printing printers has increased, there has been a demand for higher ink densities. In order to increase the concentration of the ink, it is effective to use a vinyl sulfone type reactive dye having high solubility in water or a water-soluble organic solvent. However, since the vinyl sulfone type reactive dye generates an acid in the process of changing the sulfatoethyl sulfone (SES form) to the vinyl sulfone (VS form) during storage (the reaction of the formula (1) described later). , There was a problem that pH stability was low. Further, the image formed by using the ink containing the vinyl sulfone type reactive dye has a problem that it easily retains water and a water-soluble organic solvent and is difficult to dry (the dryness of the printed matter is low).

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

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

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

However, when a large amount of urea is added to the ink containing the vinyl sulfone type reactive dye, the amino groups constituting the urea attack the sulfatoethyl sulfone (SES form) of the vinyl sulfone type reactive dye, and the following formula (1) Reaction 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 of the vinyl sulfone (VS body) (the reaction of the following formula (2)) easily proceeds in competition with the reaction between the vinyl sulfone (VS body) and the fabric.
D-SO ₂ CH = CH ₂ (VS body) + H ₂ O
→ D-SO _2- CH ₂ CH _2- OH (Hy form) ... (2)
As a result, the content ratio of the non-reactive hydroxyethyl sulfone (Hy form) increases in the ink, and the content ratio of the reactive vinyl sulfone (VS form) decreases, so that the color of the image is tinted. There is a problem that the density tends to decrease and the print stability tends to decrease.

Further, under acidic conditions, urea is easily denatured (decomposed) and solidified, so that the ink tends to thicken under long-term storage and the long-term storage stability tends to decrease.

Patent Document 1 mainly relates to an ink containing a pigment or 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. No problem of deterioration of print stability (print stability due to hydrolysis reaction of vinyl sulfone (VS form)), which is a problem with ink, has not been suggested.

The present invention has been made in view of the above circumstances, and even if a vinyl sulfone type reactive dye is contained in a high concentration, it has appropriate pH stability and dryness of a printed matter, and has good print stability. An 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 inkjet printing ink containing a reactive dye containing a vinyl sulfone type reactive dye, urea, a cyclic urea compound, and water, and having a pH of 3.0 to 5.5.
[2] The inkjet printing ink according to [1], wherein the cyclic urea compound is a solid at room temperature.
[3] The inkjet 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 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 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 to the cyclic urea compound is urea: cyclic urea compound = 10: 90 to 50:50 (mass ratio). ink.
[7] The inkjet printing ink according to any one of [1] to [6], wherein the cyclic urea compound is ethylene urea.
[8] The vinyl sulfone type reactive dye is C.I. I. The inkjet printing ink according to any one of [1] to [7], which comprises Reactive Black 5.
[9] A step of ejecting a droplet of the inkjet printing ink according to any one of [1] to [8] from a recording head to form an image on a cloth to which a hydrophilic resin having a hydroxy group is applied. An inkjet printing method comprising a step of heating a fabric on which an image is formed to fix the image.
[10] The method for inkjet printing according to [9], wherein the fabric contains cellulose fibers or protein fibers.

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

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

The present inventors replace a part of urea with a cyclic urea compound in an ink containing a vinyl sulfone type reactive dye; that is, by combining urea and a cyclic urea compound, appropriate pH stability and printed matter are obtained. It was found that print stability and long-term storage stability can be improved while maintaining drying property.

The reason for this is not clear, but it can be considered as follows. That is, since the cyclic urea compound does not have a highly basic amino group, it does not promote the reaction for producing a vinyl sulfone (VS form) (the reaction of the above formula (1)), and as a result, vinyl. It does not promote the hydrolysis reaction of the sulfone (VS compound) (the reaction of the above formula (2)). As a result, it is possible to suppress an excessive increase in non-reactive hydroxyethyl sulfone (Hy form) in the ink, so that it is easy to reduce variations in the color and density of the image (it is easy to improve print stability). ..
Further, since the cyclic urea compound is not easily deteriorated (decomposed) even under acidic conditions, the ink is not easily thickened even under long-term storage, and the long-term storage stability is not easily impaired.
Therefore, even an ink containing a vinyl sulfone-type reactive dye at a relatively high concentration can improve print stability and long-term storage stability while having 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 the ink contains a vinyl sulfone type reactive dye, the drying property of the printed matter can be improved. The present invention has been made based on these findings.

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

(Reactive dye)
The reactive dye contained in the inkjet 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"). Vinyl sulfone-type reactive dyes have higher solubility in water and water-soluble organic solvents than reactive dyes having a monochlorotriazine group and no vinyl sulfone groups (hereinafter, also referred to as "monochlorotriazine-type reactive dyes"). Therefore, not only is it easy to increase the concentration of the reactive dye in the ink, but it also has high dyeability.

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 pigment base. Examples of the dye matrix include pyrazolone azos, γ-acid azos, acrylate azos, anthraquinones, and dysazo silicates. 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 with 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 dyeing property on the fabric, but one or more of the two or more functional groups may be a vinyl sulfone group. Just do it. Reactive dyes in which one or more of the two or more functional groups are vinyl sulfone groups are referred to as reactive dyes having two vinyl sulfone groups in one molecule (hereinafter, also referred to as "vinyl sulfone type homogenous bifunctional reactive dyes"). 1. A reactive dye having one vinyl sulfone group and one monochlorotriazine group in one molecule (hereinafter, also referred to as “heterogeneous bifunctional reactive dye”) is included. The vinyl sulfone type reactive dye used in the present invention is preferably a vinyl sulfone type homogenous bifunctional reactive dye from the viewpoint of further enhancing the dyeing property on the fabric.

When a heterogeneous bifunctional reactive dye is used as the vinyl sulfone type reactive dye, the reaction between the reactive dye and the fabric may cause not only the above-mentioned nucleophilic addition reaction but also a nucleophilic substitution reaction. This is caused by the nucleophilic substitution reaction of the monochlorosubstituted 1,3,5-triazine-2-yl skeleton chloro group of the heterologous bifunctional dye with the hydroxyl group of the fabric.

Examples of vinyl sulfone-type reactive dyes include C.I. I. Reactive Yellow 15, C.I. I. Reactive Yellow 37, C.I. I. Reactive Yellow 42; C.I. 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; C.I. 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. I. Reactive Black 5 is preferred.

The reactive dye contained in the inkjet 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. When the content of the reactive dye is 15% by mass or more with respect to the total mass of the ink, the concentration of the ink is likely to be high, and when it is 30% by mass or less, the ink is difficult to thicken, so that 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 type reactive dye is preferably 50% by mass or more with respect to 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 dyeability can be 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, based on the total mass of the reactive dye.

(urea)
Urea can maintain the pH of the ink in a predetermined range, make it difficult for water in the ink to volatilize on the nozzle surface, and improve injection 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, the pH of the ink is easily stabilized, and when it is 10% by mass or less, it is possible to suppress an excessive hydrolysis reaction of the vinyl sulfone (VS form). Therefore, the print stability is not easily impaired. Further, since the thickening of the ink due to the decomposition of urea under long-term storage is unlikely to occur, the long-term storage stability is not easily impaired. Further, since the content ratio of the solid component in the ink does not increase too much, the ink is less likely to thicken and the injection stability is less likely to be 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% by mass, more preferably 15 to 40% by 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 injection 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 room temperature or liquid at room temperature. The cyclic urea compound is preferably solid at room temperature, and 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 the ink itself from drying, so that it is easy to improve the injection stability. Further, since the content ratio of the liquid component in the ink can be relatively reduced, the drying property of the printed matter can be easily improved. 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 does not increase too much, so that the ink is less likely to thicken and the injection stability is less likely to be 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, more preferably 50 to 100% by mass, based on 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 hydrolysis of the vinyl sulfone (VS form) is not excessively promoted, and print stability can be easily obtained. Specifically, the content ratio of urea to 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 form) is not promoted too much, so that the print stability is improved. Cheap. Further, since it is easy to suppress the thickening of the ink due to the decomposition of urea under long-term storage, the long-term storage stability is not easily impaired. The content ratio of urea to 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 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 (eg, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol);
Amines (eg, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholin, N-ethylmorpholin, 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 (eg, dimethyl sulfoxide) and the like are included.

(Other additives)
The inkjet printing ink of the present invention may further contain other additives such as surfactants, preservatives, fungicides, and pH adjusters.

[Surfactant]
Examples of surfactants that may be used in the present invention include dialkyl sulfosuccinates, alkylnaphthalene sulfonates, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene poly. Includes oxypropylene block copolymers, alkylamine salts, quaternary ammonium salts, silicon-based surfactants, fluorine-based surfactants, and the like. Among these, the acetylene glycol-based surfactant has a relatively low foaming property and can adjust the surface tension of the ink. Therefore, the ejection property of the ink from the inkjet recording head is improved.

[Preservatives, fungicides]
Examples of preservatives and fungicides that may be used in the present invention include aromatic halogen compounds (eg, 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 fungicides enhance the storage stability of ink.

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

(Physical characteristics of ink)
The pH of the inkjet 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-mentioned vinyl sulfone type reactive dye tends to be stably present, but also corrosion of the nozzle and the like can be suppressed. The pH of the ink can be measured at 25 ° C. using the HM-20S type manufactured by DKK-TOA CORPORATION.

The inkjet printing 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 property from an inkjet recording head. It is more preferably 40 mPa · s, and particularly preferably 5 to 20 mPa · s. The viscosity of the ink can be measured with a cone plate type 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. When the surface tension of the ink is 30 mN / m or more, the wettability of the ink to the cloth does not become too high, so that it is easy to suppress the blurring of the image. On the other hand, when the surface tension is 60 mN / m or less, the wettability of the ink to the cloth is not too low, so that the penetrating power of the ink is not easily impaired.

(Ink preparation)
The inkjet printing ink of the present invention is produced through the steps of mixing the above-mentioned reactive dye, urea, a cyclic urea compound, water, and if necessary, other components.

2. 2. Inkjet printing method In the inkjet printing method using the inkjet printing ink of the present invention, droplets of the inkjet printing ink of the present invention are ejected from a recording head to form an image on a fabric to which a hydrophilic resin having a hydroxy group is applied. It includes a step and a step of heating the fabric on which the image is formed to fix the image on the fabric. The fabric to which the hydrophilic resin having a hydroxy group is attached can be obtained by applying a pretreatment agent containing the hydrophilic resin having a hydroxy group to the fabric.

That is, in the inkjet printing method of the present invention, (1) a step of applying a pretreatment agent containing a hydrophilic resin having a hydroxy group (pretreatment step) to the cloth, and (2) a cloth to which the pretreatment agent is applied. Includes a step of ejecting droplets of printing ink to form an image (ink application step) and (3) a step of heating the cloth on which the image is formed to fix the image on the cloth (color development step). If necessary, (4) a step of drying the cloth after applying ink (pre-drying step), (5) a step of removing dyes and pretreatment agents that could not be dyed on the cloth (cleaning step), and ( 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 methods for applying the pretreatment agent to the fabric include a pad method, a coating method, a spray method, an inkjet method and the like. By these methods, the pretreatment agent can be applied onto the fabric. Examples of the fabric to which the pretreatment agent is applied include fabrics having an ink receiving layer described in JP-A-62-53492, and anti-reduction agents and alkaline agents described in JP-A-3-46589. The contained cloth and the like are included.

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

The pretreatment agent preferably contains at least a resin component, an alkaline agent, and a hydrotropy agent, and may further contain additives such as an antioxidant, a preservative, and 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 beans, starches, seaweeds such as sodium alginate and furinate, plant skins such as pectic acid, methyl fiber, ethyl fiber, and hydroxy. Fiber element 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 silat gum and roast bean gum, argin derivatives, poly Includes synthetic glues such as vinyl alcohol and polyacrylic acid ester, emulsions and the like.

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 hydrogen carbonate). Alternatively, it includes alkali metal bicarbonate and the like, organic acid metal salts such as calcium acetate and barium acetate, ammonia and ammonia compounds, and sodium trichloroacetate which is an alkaline agent under steaming or dry heat. 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, more preferably 0.5 to 5% by mass, based on the total mass of the fabric. The presence of an appropriate alkaline agent on the fabric makes it possible to reliably dye the printing ink containing the reactive dye. Therefore, it is preferable that the fabric contains an alkaline agent in advance.

Examples of hydrotropy agents include alkyl ureas such as urea, ethylene urea, dimethylurea, thiourea, monomethylthiourea and dimethylthiourea. This is because the image density is improved by adding the hydrotropy agent.

The amount of the pretreatment agent applied (squeezing ratio) 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 an antioxidant, a preservative, or a chelating agent, if necessary. The anti-reduction agent may be sodium m-nitrobenzene sulfonate or the like. The preservative may be the preservative exemplified as the preservative of the printing ink, or may be the same. The chelating agent may be ethylenediaminetetraacetate, nitrilotriacetate, hexametaphosphate, pyrophosphate, metaphosphate or the like.

The pretreatment agent applied to the fabric can also be heat-dried using warm 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 (as a pretreatment agent) is applied, but in terms of improving dyeability, fibers that can be dyed with a reactive dye; that is, , It is preferable to contain a fiber having a hydroxy group. Examples of fibers having a hydroxy group include cellulose fibers such as cotton and protein fibers such as silk. The cloth may be in any form of these fibers, such as a woven cloth, a non-woven fabric, and a knitted cloth. Further, the fabric that can be used in the present invention may be composed of only fibers that can be dyed with a reactive dye, but may be a blended woven fabric or a blended non-woven fabric with rayon, polyurethane, polyester, acrylic or the like. .. The thickness of the fibers constituting the fabric is preferably in the range of 10 to 100d.

(Ink application process)
The ink application step is a step of ejecting droplets of the inkjet printing ink from the inkjet recording head toward the fabric to form an image before color development. While moving the cloth relative to the head carriage on which a plurality of inkjet recording heads are mounted, droplets of the inkjet printing ink set are ejected 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. From the viewpoint of suppressing fluctuations in ink viscosity due to fluctuations in ink temperature, it is preferable to keep the ink temperature at 25 ° C.

(Preliminary drying process)
The pre-drying step is a step of drying the fabric after applying the ink. Although not particularly limited, the pre-drying preferably involves 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, an irradiation method and the like. Specifically, ink may be applied to the fabric, and the fabric may be dried under the above conditions and methods before the fabric is wound up.

(Coloring process)
The color development step is to heat the fabric after applying the ink (after pre-drying when the pre-drying step is included) to dye the fabric with a reactive dye that is not sufficiently dyed into the fabric, and to dye the fabric with the original ink. This is a step of expressing a hue.

The color development temperature (heating temperature) depends on the color development method (heating method), but from the viewpoint of strengthening the dyeing of the reactive dye on the fabric, it is preferably 95 ° C. or higher and lower than 220 ° C., and 95 ° C. or higher 190 ° C. The temperature is more preferably 100 ° C or higher, and further preferably 100 ° C or higher and 180 ° C or lower.

The color developing method (heating method) may be a conventionally known method, and is appropriately selected depending on the printing ink, the cloth, or the like. For example, steaming with steam; baking with dry heat, thermosol; HT steamer with superheated steam, etc. are included. Of these, a method of fixing the reactive dye in the ink with high-temperature steam (steaming method) and a dry heat method (baking method) are preferable.

In the steaming method using high-temperature steam, if the heating temperature is too low, a large amount of liquid water is present, so that the reactive dye contained in the dark ink or light ink tends to hydrogen bond with liquid water other than the cloth. Therefore, it becomes easy to be washed away with water, and it may not be possible to dye it sufficiently. Therefore, from the viewpoint of strengthening the dyeing of the reactive dye on the fabric, the heating temperature is preferably 95 ° C. or higher, more preferably 100 ° C. or higher. For example, cellulosic fibers are preferably treated at 95-105 ° C. for 5 to 15 minutes; amide fibers such as silk and wool are preferably treated at 95-105 ° C. for 20-40 minutes. .. Further, the cloth to which the ink has been applied may be colored immediately, or may be colored after a lapse of time.

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

(Washing process)
The washing step is a step of removing the reactive dye and the pretreatment agent that could not be dyed on the cloth after the color development step of the cloth. A conventionally known cleaning method can be used for removing the reactive dye that could not be dyed on the cloth, and it is appropriately selected depending on the printing ink, the cloth, and the like. For example, cellulose fibers are generally washed with water and hot water, then treated with a soaping bath containing a nonionic detergent, and then washed with hot water and water. By removing the undyed reactive dye, washing fastness, water fastness, sweat fastness, etc. tend to be improved. If there is a reactive dye that could not be dyed on the fabric, it is difficult to obtain washing fastness, water fastness, sweat fastness and the like.

(Drying process)
The drying step is a step performed after the washing step to dry the washed fabric. The drying method is not particularly limited, but may be a method of squeezing the washed cloth, drying it, or drying it using a dryer (heat roll, iron, etc.).

(Inkjet printing equipment)
In the following, an apparatus for performing the ink application step and the pre-drying step will be described with reference to the drawings, but the inkjet printing apparatus is not limited to this.

FIG. 1 is a partial schematic view showing an example of the configuration of an inkjet printing apparatus. The inkjet printing apparatus includes a transport means 2 for transporting the cloth P, a head carriage 5 equipped with a plurality of inkjet recording heads (not shown) for ejecting droplets of the inkjet printing ink onto the cloth P, and warm air to the cloth P. It has a warm air applying means 6 for applying.

The transporting means 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 transfer roller 23, and circulates between the support roller 22 and the transfer roller 23. The nip roller 24 is arranged so as to face the transport roller 23 via the adhesive belt 21.

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

When the transport roller 23 is driven, the fabric P arranged on the upper surface of the adhesive belt 21 is transported to the lower surface of the nip roller 24. The cloth 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. The plurality of inkjet recording heads mounted on the head carriage 5 eject droplets of the inkjet printing ink and land them on a certain area (landing area) of the fabric to which the pretreatment agent is applied to form an image. Next, the temperature-controlled air or warm air is blown from the warm air applying means 6 to dry the image formed on the cloth P.

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

1. 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)
Dimethylethylene 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. 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 an antiseptic. Ion-exchanged water was added to the obtained 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)
The 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 an HM-20S type manufactured by DKK-TOA CORPORATION. After storing this ink at 25 ° C. for 4 weeks, the pH of the ink was measured in the same manner. The amount of change in the pH of the ink before and after storage ΔpH (= pH of the ink before storage-pH of the ink after storage) was calculated and evaluated based on the following criteria.
⊚: ΔpH is ± 0.2 or less ○: ΔpH is more than ± 0.2 ± 0.3 or less ○ △: ΔpH is more than ± 0.3 ± 0.5 or less △: ΔpH is more than ± 0.5 ± 1. 0 or less ×: Δ pH is more than ± 1.0 The pH of the ink is judged to be good if it is in the range of 3 to 5.5.
If the pH stability of the ink was Δ or higher, it was judged to be good because there was no problem in practical use.

(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 storing this ink at 25 ° C. for 4 weeks, the viscosity of the ink was measured by the same method. The amount of change in ink viscosity before and after storage (= viscosity of ink before storage-viscosity of ink after storage) was calculated and evaluated based on the following criteria.
⊚: Viscosity change amount is ± 0.4 mPa · s or less ○: Viscosity change amount is more than ± 0.4 mPa · s ± 0.5 mPa · s or less ○ △: Viscosity change amount is ± 0.5 mPa · s more than 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 △ If it is more than practical It was judged to be good because it was at a level that was not a problem.

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

<Inkjet printing method>
(Pretreatment process)
A 100% cotton cloth (with cotton broad sill, manufactured by Color Dyeing 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 mass Urea (hydrotropy agent): 10 parts by mass Sodium hydrogen carbonate (alkali agent): 5 parts by mass Ion-exchanged water: 80 parts by mass

(Ink application process)
The obtained ink was set in Nassenger V (manufactured by Konica Minolta). A solid image was formed using the obtained ink in the main scan of 540 dpi and the sub scan of 540 dpi. Note that dpi represents the number of ink droplets (dots) per 2.54 cm.

(Coloring process)
The fabric on which the image was formed was steamed for 8 minutes under the conditions of 100% relative humidity and 103 ° C. to fix and color the dye.

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

(Print stability)
The obtained ink was stored at 50 ° C. for 4 weeks, and then an image was formed under the same conditions as described above. The colortric values (L *, a *, b *) of the solid image formed using the ink before storage and the solid image formed using the ink after storage were measured using the colorimeter X-Rite938, respectively. It was measured. Then, the color value of the ink before storage (L ₁ *, a ₁ *, b ₁ *) and the color value of the ink after storage (L ₂ *, a ₂ *, b ₂ *) are expressed by the following formulas. By applying, ΔE was calculated.
ΔE = [(L ₂ ^* −L ₁ ^* ) ² + (a ₂ ^* −a ₁ ^* ) ² + (b ₂ ^* −b ₁ ^* ) ² ] ^1/2
Then, the print stability was evaluated based on the following criteria.
⊚: ΔE <0.5
◯: 0.5 ≦ ΔE <1.0
○ Δ: 1.0 ≦ ΔE <1.5
Δ: 1.5 ≦ ΔE <2.0
X: 2.0 ≤ ΔE
If it is Δ or more, it is judged that there is no problem in practical use and it is good.

(Injection stability)
Ink from the inkjet head was ejected for a certain period of time at 25 ° C. and 50% RH. Then, it was left for 30 minutes, the ink was ejected again, and the ejection property at that time was observed with a drop watcher. Then, the re-injectability after being left for 30 minutes was evaluated based on the following criteria.
⊚: Re-injection is possible without defects by throwing out 200 shots or less (operation to refresh the ink on the nozzle surface by throwing away) ○: Re-injection is possible without defects by discharging more than 200 shots and 500 shots or less △: It is possible to re-inject without defects by throwing out more than 500 shots and 1000 shots or less. ×: It cannot be dealt with by throwing out, and maintenance (manual cleaning of the nozzle surface) is required. It was judged to be good.

(Drying property of printed matter)
After the printed matter on which the solid image was formed was dried at 80 ° C. for 1 minute (after the pre-drying step), the presence or absence of color transfer when the cloths were stacked was visually observed. Then, the evaluation was made based on the following criteria.
◎: No color transfer ○: Slight color transfer is observed △: Color transfer is slightly observed, but there is no problem in practical use ×: Color transfer is noticeably observed, and the level is at least a problem in practical use △ For example, it was judged that there was no problem in practical use and it was good.

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 indicates glycerin, EG indicates ethylene glycol, and PG indicates propylene glycol. The unit of the numerical value of the composition in the table is a mass part.

As shown in Table 1, the inks of Examples 1 to 10 have good print stability even if they contain a vinyl sulfone type reactive dye, while having appropriate pH stability and dryness of the printed matter. It can be seen that it has long-term storage stability.

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

Further, by setting the total content of urea and the cyclic urea compound to 8% by mass or more, the content ratio of the liquid component in the ink can be reduced, so that the dryness of the printed matter can be improved (Example 3, Example 3). (Comparison of 4 to 7 and 10), it can be seen that when the content is 20% by mass or less, the viscosity of the ink does not increase too much and the ejection stability is not easily impaired (comparison between Examples 6 and 7).

Further, 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 form) is suppressed, so that the print stability is improved (Example). Comparison of inks 5 and 6).

Further, it can be seen that when the cyclic urea compound is ethylene urea which is solid at room temperature, it is easy to improve the drying property and injection stability of the printed matter (compared to 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 injection stability. It is considered that this is because the ink has low moisturizing property because it does not contain the cyclic urea compound, and the water contained in the ink evaporates in the vicinity of the nozzle and is easily dried. Further, it can be seen that the ink of Comparative Example 4 has low print stability and long-term stability. It is considered that the reason why the print stability is lowered is that urea tends to promote the production reaction of the vinyl sulfone (VS body), and accordingly, the hydrolysis reaction of the vinyl sulfone (VS body) is also easily promoted. Be done. It is considered that the decrease in long-term stability is due to the deterioration (decomposition) of urea during storage and the thickening of the ink.

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.

An inkjet printing ink that has appropriate pH stability and dryness of printed matter, and also has good print stability and long-term storage stability even if it contains a vinyl sulfone type reactive dye in a high concentration. The inkjet printing method used can be provided.

P Cloth 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 (9)

A reactive dye containing a vinyl sulfone type reactive dye, urea, a cyclic urea compound, and a water, a jet printing ink pH is Ru der 3.0 to 5.5,
The content of the vinyl sulfone type reactive dye is 15 to 30% by mass with respect to the total mass of the ink.
The urea content is 2 to 10% by mass with respect to the total mass of the ink.
The cyclic urea compound contains ethylene urea, propylene urea or dimethylethylene urea, and contains
The content ratio of the urea to the cyclic urea compound is urea: cyclic urea compound = 10: 90 to 50:50 (mass ratio).
Ink inkjet printing ink. The cyclic urea compound is solid at room temperature.
The inkjet printing ink according to claim 1. 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.
The inkjet printing ink according to any one of claims 1 or 2 . The cyclic urea compound is ethylene urea.
The inkjet printing ink according to any one of claims 1 to 3 . The vinyl sulfone type reactive dye is C.I. I. Including Reactive Black 5
The inkjet printing ink according to any one of claims 1 to 4 . The content ratio of the urea to the cyclic urea compound is urea: cyclic urea compound = 29: 71 to 50:50 (mass ratio).
The inkjet printing ink according to any one of claims 1 to 5 . The pH of the ink is 3.0 to 5.0.
The inkjet printing ink according to any one of claims 1 to 6 . A step of ejecting droplets of the inkjet printing ink according to any one of claims 1 to 7 from a recording head to form an image on a fabric to which a hydrophilic resin having a hydroxy group is applied.
Including a step of heating the fabric on which the image is formed to fix the image.
Inkjet printing method. The fabric contains cellulose fibers or protein fibers.
The inkjet printing method according to claim 8 .

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