JP2013224498A - Inkjet printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet printing method having excellent stability in density and color tone of a formed image by suppressing decomposition of a reactive dye contained in an ink during storage or after impacting of a fabric, and adjusting a dyeing property between a cyan ink and ink other than the cyan ink.SOLUTION: An inkjet printing method comprises the step of: discharging a droplet of each ink in an ink set from an inkjet recording head to a fabric, the ink set including a cyan ink containing at least a vinylsulfon-based reactive dye and a buffer, and ink other than the cyan ink, containing a monochlorotriazine-based reactive dye and a buffer.

Description

  The present invention relates to an inkjet printing method.

  The ink jet image printing method is a method in which fine droplets of ink are ejected from an ink jet recording head and landed on a recording medium to be printed. The ink jet method is advantageous in that its mechanism is relatively simple, inexpensive, and can form a high-definition and high-quality image. Development of a so-called ink-jet printing method in which an image is formed on a fabric by the ink-jet method, taking advantage of the ink-jet method, has been promoted.

  Ink-jet textile printing methods generally include a pre-treatment step for imparting a resin component or an alkali component to a fabric, a step for ejecting textile printing ink by the ink-jet method to land on the fabric, and fixing the dye in the landed ink by heat treatment, etc. A step of color development and a cleaning step of removing excess printing ink and pretreatment agent components in the fabric are performed. Unlike the conventional roller textile printing, the ink jet textile printing method does not require the production of a plate. In addition, an image rich in gradation can be formed. Furthermore, the amount of ink used in the ink jet textile printing method is only the amount necessary for image formation. Therefore, the inkjet textile printing method is an excellent image forming method with less waste liquid as compared with the conventional method.

  The types of color materials used in inkjet printing inks are mainly acid dyes, disperse dyes, reactive dyes or pigments. As an image forming method for a fabric mainly composed of cellulose, an ink jet printing method using a reactive dye has been proposed. In general, the reactive dye contained in the textile printing ink is preferably a monochlorotriazine reactive dye excellent in hue and image fastness (see Patent Document 1).

  However, phthalocyanine-based monochlorotriazine-based reactive dyes are inferior to other fabrics in monochromatic triazine-based reactive dyes (so-called dyed feet are slower). For this reason, an image formed with a cyan ink containing a phthalocyanine-based monochlorotriazine reactive dye is insufficiently colored in the color development step as compared with an image of another color under the same color development conditions. In addition, the color tone of the secondary color including cyan tends to vary due to the influence of slight fluctuations in the coloring conditions. On the other hand, it is known that the dye used for cyan ink is a vinyl sulfone reactive dye having higher reactivity, so that the dyeing feet with other colors can be aligned.

JP-A-2005-47990

  However, since the vinyl sulfone reactive dye is inferior in stability over time as compared with the monochlorotriazine reactive dye, the storage stability of the ink is deteriorated. Further, after the ink has landed on the fabric, decomposition of the reactive dye in the ink is promoted by the alkali component contained in the pretreatment agent. As a result, the density and color tone of the image may vary.

  The present invention has been made in view of the above circumstances, suppresses decomposition of reactive dyes contained in ink after storage or after landing on a fabric, and dyeability of cyan ink and inks other than cyan ink Is intended to provide an ink-jet printing method that is excellent in the stability of the density and color tone of the formed image.

The above object of the present invention is achieved by the following configurations.
[1] Ink droplets of each ink of an ink set including at least a cyan ink containing a vinylsulfone reactive dye and a buffer and an ink other than a cyan ink containing a monochlorotriazine reactive dye and a buffer An ink-jet printing method comprising a step of discharging a recording head onto a fabric.
[2] The inkjet printing method according to [1], wherein the content of the buffer in the cyan ink is larger than the content of the buffer in the ink other than the cyan ink.
[3] The inkjet printing method according to [1] or [2], wherein the cyan ink has a pH of 2.5 to 5.5.
[4] The inkjet printing method according to any one of [1] to [3], wherein the pH of the ink other than the cyan ink is 7 to 9.
[5] The buffer contained in the cyan ink is at least a first phosphoric acid, a second phosphoric acid, a third phosphoric acid, acetic acid, oxalic acid, boric acid, phthalic acid, or citric acid, or a sodium salt, potassium salt, or ammonium salt thereof. The inkjet printing method according to any one of [1] to [4], comprising one.
[6] The content of the buffer in the cyan ink is 0.1 to 2.0% by mass with respect to the entire ink, according to any one of [1] to [5] The inkjet printing method as described.

  According to the inkjet textile printing method of the present invention, the decomposition of the reactive dye contained in the ink after storage or after landing on the fabric is suppressed, and the dyeing properties of cyan ink and ink other than cyan ink are combined, It is possible to provide an ink-jet printing method that is excellent in the density and color tone stability of a formed image.

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

1. Ink-jet printing ink The printing ink used in the present invention includes at least a cyan ink containing a vinylsulfone reactive dye and a buffer, and an ink other than a cyan ink containing a monochlorotriazine reactive dye and a buffer. . These inks may further contain a water-soluble organic solvent and other additives.

<Cyan ink>
(Vinyl sulfone reactive dye)
The vinyl sulfone reactive dye contained in the cyan ink used in the present invention is a cyan dye having a vinyl sulfone group. The pigment matrix of the cyan dye is preferably phthalocyanine. An ink containing a vinyl sulfone reactive dye with respect to a monochlorotriazine reactive dye is characterized by high dyeing properties. .

The vinyl sulfone reactive dye has an equilibrium relationship between the following general formula (1) and the structure of the following general formula (1 ′).
D—SO ₂ —CH ₂ CH ₂ —O—SO ₃ Na (1) ⇔ D—SO ₂ CH═CH ₂ + HO—SO ₃ Na (1 ′)
[Wherein D represents a cyan dye matrix]

  The vinyl sulfone reactive dye reacts with the fabric. For example, the vinyl group of the vinyl sulfone reactive dye undergoes a nucleophilic addition reaction to the hydroxyl group of the fabric, and the vinyl sulfone dye is dyed onto the fabric.

  The vinyl sulfone reactive dye used in the present invention may have one or two or more vinyl sulfone groups.

  As the vinyl sulfone reactive dye, a cyan dye described in JP-A-62-18474 can be preferably used. Examples of vinyl sulfone reactive dyes include C.I. I. Reactive blue 19, 21, 38, 229 and the like are included.

  The content of the vinyl sulfone reactive dye contained in the cyan ink used in the present invention is preferably 3% by mass to 20% by mass with respect to the entire ink. In particular, when a plurality of printing inks of the same color are used, the content of the vinyl sulfone reactive dye in the printing ink having the highest dye concentration is preferably 10% by mass or more and less than 20% by mass. When the content of the vinyl sulfone reactive dye is less than 3% by mass, the color density on the fabric is low. On the other hand, when the reactive dye exceeds 20% by mass, the ink viscosity increases, and the ejectability from the ink jet recording head decreases.

  Phthalocyanine-based monochlorotriazine-based reactive dyes are inferior to other fabrics in monochromatic triazine-based reactive dyes (so-called dyed feet are slow). For this reason, in the color development step, color development is insufficient compared to images of other colors under the same color development conditions. In addition, the color tone of the secondary color including cyan is likely to vary due to the influence of slight variations in the coloring process. On the other hand, the cyan ink used in the present invention contains a vinyl sulfone reactive dye having a higher reaction speed even if it is a phthalocyanine dye. For this reason, it is possible to align the dyeing feet with the ink other than the cyan ink containing the monochlorotriazine-based reactive dye, and to suppress variations in the color tone of the formed image.

(Buffering agent)
The buffering agent is a solution having a property (buffering action) that the pH does not change greatly even when an acid or a base is added from the outside. In general, two or more kinds of buffering agents coexist with a weak acid (such as acetic acid) and a salt thereof (such as sodium acetate) or a weak acid salt (such as sodium carbonate). By including a buffer in the textile printing ink, even when some acid or base is added to the textile printing ink, or when the density of the ink composition changes due to evaporation or dilution of the textile printing ink, the pH hardly changes. The pH of the buffer can be determined freely to some extent by the combination of contained substances and the content ratio.

  The pH of the cyan ink is preferably 2.5 to 5.5 from the viewpoint of ink storage stability. Buffers for adjusting the pH of the cyan ink include primary phosphoric acid, secondary phosphoric acid, tertiary phosphoric acid, acetic acid, oxalic acid, boric acid, phthalic acid, or citric acid, or sodium, potassium, or ammonium salts thereof. At least one is preferred.

  From the viewpoint of suppressing variations in density and color tone of the formed image, it is preferable that the content of the cyan ink buffer is 0.1 to 2.0 mass% with respect to the entire ink. Further, the content is preferably larger than the content of the buffer of the ink other than the cyan ink described later. When the content of the buffer is less than 0.1% by mass, it is difficult to keep the pH of the printing ink constant. On the other hand, when the content of the buffering agent is more than 2.0% by mass, the buffering agent may precipitate in the ink and clog the nozzles of the ink jet recording head.

(Water-soluble organic solvent)
The cyan ink used in the present invention may further contain a water-soluble organic solvent.

Examples of water-soluble organic solvents 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, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.),
Heterocycles (for example, 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.

  The content of the water-soluble organic solvent is preferably 5 to 50% by mass with respect to the whole ink. By setting the content of the water-soluble organic solvent in the above range, clogging due to drying on the ink jet recording head nozzle surface can be suppressed.

(Other additives)
[Urea compound]
The cyan ink used in the present invention may further contain a urea compound as a dyeing assistant in order to increase the dyeing efficiency of the dye on the fabric. The urea compound may be urea, thiourea, alkyl-substituted urea, alkylthioureas and the like. More specific examples include urea, ethylene urea, dimethyl urea, monomethyl thiourea, thiourea, dimethyl thiourea, and the like. From the viewpoint of ink storage stability, ethylene urea is preferred. The content of the urea compound is preferably 0.1 to 10% by mass with respect to the whole ink.

[Surfactant]
The cyan ink used in the present invention may further contain a surfactant. Examples of surfactants include dialkyl sulfosuccinates, alkyl naphthalene sulfonates, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene / polyoxypropylene block copolymers, alkyls Amine salts, quaternary ammonium salts, silicon surfactants, fluorine surfactants and the like are included. Among these, acetylene glycol surfactants are preferable from the viewpoint of injection stability because they have relatively low foaming properties and can adjust surface tension. The content of the surfactant is preferably adjusted so that the surface tension of the ink is 30 to 60 mN / m. Specifically, it is preferably 0.0001 to 5% by mass with respect to the entire ink.

[Preservatives, antifungal agents]
The cyan ink used in the present invention may further contain a preservative and an antifungal agent from the viewpoint of long-term storage stability of the ink. Examples of antiseptics and antifungal agents include aromatic halogen compounds (for example, Preventol CMK), methylene dithiocyanate, halogen-containing nitrogen sulfur compounds, 1,2-benzisothiazolin-3-one (for example, PROXEL GXL), etc. Is included.

(Preparation method of cyan ink)
The cyan ink used in the present invention is produced through a step of mixing a vinyl sulfone reactive dye, a buffer, and other components as required.

<Ink other than cyan ink>
(Monochlorotriazine reactive dye)
The ink other than the cyan ink used in the present invention can be a yellow ink, a magenta ink, a black ink, or the like. At least one ink other than the cyan ink contains a monochlorotriazine reactive dye. From the viewpoint of image fastness and the like, it is preferable that all inks other than cyan ink contain a monochlorotriazine reactive dye.

  The monochlorotriazine reactive dye is a reactive dye having a monochloro-substituted 1,3,5-triazin-2-yl skeleton.

  The monochlorotriazine reactive dye reacts with the fabric. For example, the chloro group of the monochlorotriazine reactive dye undergoes a nucleophilic substitution reaction with the hydroxyl group of the fabric, so that the monochlorotriazine reactive dye is dyed onto the fabric.

  The monochlorotriazine group of the monochlorotriazine reactive dye contained in the ink other than cyan ink may be one or two or more.

Examples of monochlorotriazine reactive dyes include
C. I. Reactive Yellow 3, 6, 12, 18, 95, 99,
C. I. Reactive Orange 2, 5, 9, 12, 13, 20,
C. I. Reactive Red 3, 4, 7, 15, 16, 24, 29, 31, 32, 33,
43, 45, 46, 58, 59, 226, 245,
C. I. Reactive violet 1, 2,
C. I. Reactive Blue 2, 3, 5, 7, 13, 14, 15, 25, 26, 39, 40, 41, 46, 49, 176,
C. I. Reactive Green 5, 8,
C. I. Reactive Brown 1, 2, 7, 8, 9, 11, 14,
C. I. Reactive black 1, 3, 8, 10, 12, 13, 39, etc. are included.

  The content of the monochlorotriazine reactive dye contained in the ink other than the cyan ink used in the present invention is preferably 3% by mass to 20% by mass with respect to the entire ink. In particular, when a plurality of printing inks of the same color are used, the content of the monochlorotriazine reactive dye in the printing ink having the highest dye concentration is preferably 10% by mass or more and less than 20% by mass. When the content of the monochlorotriazine reactive dye is less than 3% by mass, the color density on the fabric is low. On the other hand, when the reactive dye exceeds 20% by mass, the ink viscosity increases, and the ejectability from the ink jet recording head decreases.

(Buffering agent)
The pH of the ink other than the cyan ink is preferably 7 to 9 from the viewpoint of the storage stability of the ink. The buffer for adjusting the pH of inks other than cyan ink is a weak acid (such as acetic acid) and a salt thereof (such as sodium acetate) or a salt of a weak acid (such as sodium carbonate), similar to the buffer contained in cyan ink. In general, two or more of these are allowed to coexist. Buffers contained in inks other than cyan ink are primary phosphoric acid, second phosphoric acid, third phosphoric acid, acetic acid, succinic acid, boric acid, phthalic acid, citric acid, tartaric acid, succinic acid, N, N-diethylaniline sulfone. It may be at least one of an acid or a sodium salt, potassium salt or ammonium salt thereof; an alkali metal carbonate or hydrogencarbonate.

  The content of the buffer of the ink other than the cyan ink is preferably 0.1 to 1.0% by mass with respect to the whole ink.

(Other additives)
The ink other than the cyan ink may further contain a water-soluble organic solvent, a urea compound, a surfactant, a preservative, or an antifungal agent, similarly to the cyan ink.

(Preparation method of ink other than cyan ink)
Inks other than the cyan ink used in the present invention are produced through a step of mixing a monochlorotriazine reactive dye, a buffer, and other components as required.

<Physical properties of textile printing ink>
The cyan ink and the ink other than the cyan ink used in the present invention both preferably have an ink viscosity at 25 ° C. of 1 to 40 mPa · s, and 5 to 40 mPa · s, from the viewpoint of ejection properties from the inkjet recording head. More preferably, it is more preferably 5 to 20 mPa · s.

  The surface tension of the ink at 25 ° C. is preferably 30 to 60 mN / m. When the surface tension is less than 30 mN / m, the wettability of the ink with respect to the fabric is too high, so that the image tends to bleed. On the other hand, when the surface tension is more than 60 mN / m, the wettability of the ink with respect to the fabric is lowered, and the penetrating power of the ink is likely to be lowered.

2. Inkjet textile printing apparatus and inkjet textile printing method using the same The inkjet textile printing method of the present invention comprises (1) a step of applying a pretreatment agent to a fabric (pretreatment step), and (2) a fabric to which a pretreatment agent is applied. A step of ejecting droplets of printing ink (image forming step); and (3) a step of fixing the dye landed on the fabric to the fiber (coloring step). And a step of removing the pretreatment agent (washing step) and (5) a step of drying the washed fabric (drying step). The fabric used in the present invention is preferably a cellulose-based fiber or a amide-based fiber. Specifically, it is preferable to use a cloth made of fibers such as cotton, hemp, wool, silk, viscose rayon, cupra rayon, polynosic, vinylon, or nylon. In the ink jet textile printing method of the present invention, these fabrics may be conventionally known or pretreated.

<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, or an ink jet method. By these application methods, the pretreatment agent can be applied on the fabric.

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

  Examples of resin components include natural gums such as guar and locust bean, starches, seaweeds such as sodium alginate, funari, plant skins such as pectic acid, methyl fibrin, ethyl fibrin, hydroxyethylcellulose, carboxymethylcellulose, etc. Fibrin derivatives, roasted starch, alpha starch, carboxymethyl starch, carboxyethyl starch, hydroxyethyl starch, and other processed starches, processed natural gum, roast bean gum and other natural gums, algin derivatives, polyvinyl alcohol, polyacrylic Synthetic pastes such as acid esters, emulsions and the like are included.

  Examples of the alkaline agent include sodium carbonate, sodium hydrogen carbonate, sodium hydroxide, tribasic sodium phosphate, sodium acetate and the like. This is because an appropriate alkaline substance is preferably present in order to ensure that the textile printing ink containing the reactive dye is dyed onto the fabric.

  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 rate) 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.

  In order to dry the pretreatment agent applied to the fabric, warm air, a hot plate, a heat roller, or the like can be used.

<Image forming process>
The image forming step is a step of forming a pre-colored image by ejecting cyan ink and ink droplets other than cyan ink from the inkjet recording head toward the fabric. Cyan ink and ink droplets other than cyan ink are ejected and landed on the fabric while moving the fabric relative to a head carriage on which a plurality of inkjet recording heads are mounted. The ink droplets for each color may be ejected separately or simultaneously. The surface temperature of the fabric when the ink droplets are landed is not particularly limited, but is preferably heated in the range of 35 to 70 ° C. from the viewpoint of suppressing bleeding of the pre-colored image.

<Coloring process>
The color development step is a step in which a dye in an image before a color development reaction that is not sufficiently dyed in the fabric is dyed on the fabric to develop the original hue of the ink. The method may be a conventionally known method, and includes, for example, a steaming method, an HT steaming method, a thermofix method, an alkali pad steam method, an alkali blotch steam method, an alkali shock method, or an alkali cold fix method. It is appropriately selected depending on textile printing ink, fabric, or the like. For example, when fixing the dye in the ink with high heat steam (such as a steaming method), the cellulosic fiber is preferably treated at 95 to 105 ° C. for 5 to 15 minutes, and amides such as silk and wool The fibers are preferably treated at 95-105 ° C. for 20-40 minutes. In addition, the fabric on which the image before the color development reaction is formed may be colored immediately or may be colored after a lapse of time.

<Washing process>
The washing step is a step of removing dyes and pretreatment agents that could not be dyed on the fabric after the color development step of the fabric. As the cleaning method, a conventionally known water-washing method, a soaking method, or the like can be used, and it is appropriately selected depending on a printing ink, a cloth, or the like. For example, the cellulose fiber is 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.

<Drying process>
A drying process is a process performed after the said washing | cleaning process and drying the wash | cleaned fabric. Although the drying method is not particularly limited, the washed fabric is squeezed, dried, or dried using a dryer (heat roll, iron, etc.).

<Inkjet printing device>
Hereinafter, an apparatus for performing the pretreatment process and the image forming process will be described with reference to the drawings. However, the inkjet printing apparatus used in the inkjet printing method of the present invention is not limited to this.

  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 a cloth, a head carriage 5 on which a plurality of ink jet recording heads (not shown) for discharging cyan ink and ink other than cyan ink are mounted, and warm air is applied to the cloth. And hot air applying means 6 for

  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 arranged above the fabric P. The warm air applying means 6 includes a fan 6A and a heating element 6B inside, and can control the temperature. The ink jet recording head mounted on the head carriage 5 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 less than 10 μm, nozzle clogging due to insoluble matter is likely to occur. On the other hand, when it exceeds 100 μm, the sharpness of the formed image is lowered. The ink droplet size 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 less than 4 pl, the ejected ink droplets are easily affected by the airflow in the vicinity of the head. On the other hand, when it exceeds 150 pl, the granularity of the formed image is conspicuous.

  The ink jet printing apparatus applicable to the present invention may include a printing ink control unit (not shown) that controls ejection of each color printing ink in accordance with set image forming conditions.

  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 eject cyan ink and ink droplets other than cyan ink, land on a predetermined region (landing possible region) of the fabric to which the pretreatment agent is applied, and image Form. Next, the temperature controllable wind or warm air is blown from the warm air applying means 6 to dry the image formed on the fabric P.

  In the following, the invention will be described in more detail with reference to examples. These examples do not limit the scope of the present invention.

<Ink composition>
(Reactive dye)
C. I. Reactive Blue 19 (phthalocyanine, vinylsulfone)
C. I. Reactive Blue 72 (phthalocyanine, monochlorotriazine)
C. I. Reactive Yellow 95 (monochlorotriazine series)
C. I. Reactive Red 218 (Monochlorotriazine series)
C. I. Reactive Black 39 (monochrome rotriazine)
(Water-soluble organic solvent)
Ethylene glycol Propylene glycol Glycerin (buffering agent)
Phthalic acid and sodium phthalate Citric acid and sodium citrate Sodium dihydrogen phosphate and disodium hydrogen phosphate Sodium carbonate and sodium hydrogen carbonate (water)
Ion exchange water

<Preparation of ink set 1>
(Cyan ink C1)
As a reactive dye, C.I. I. 15 parts by weight of reactive blue 19, 24 parts by weight of ethylene glycol as a water-soluble organic solvent, 4 parts by weight of propylene glycol, and 1 part by weight of phthalic acid and sodium phthalate as a buffer were mixed. Cyan ink C1 was prepared by adding ion-exchanged water so that the total amount was 100 parts by mass. The mixing ratio of phthalic acid and sodium phthalate was adjusted so that the pH of the ink was 4. The pH of the ink was measured using a HM-20S type manufactured by Toa DKK Corporation.

(Yellow ink Y2)
As a reactive dye, C.I. I. 11 parts by weight of Reactive Yellow 95, 24 parts by weight of ethylene glycol as a water-soluble organic solvent, 4 parts by weight of propylene glycol, 5 parts by weight of glycerin, 0.5 parts of citric acid and sodium citrate as a buffering agent Parts by mass were mixed. Ion exchange water was added to the resulting mixture so that the total amount was 100 parts by mass to prepare yellow ink Y1. The mixing ratio of citric acid and sodium citrate was adjusted so that the pH of the ink was 7.

(Magenta ink M1)
In the preparation of the yellow ink Y1, C.I. I. Reactive Yellow 95 (11 parts by mass) to C.I. I. Reactive Red 218 (10 parts by mass) was changed. The amount of propylene glycol and ion-exchanged water was adjusted so that the viscosity of the magenta ink M1 was 4.5 ± 0.5 mPa · s. Magenta ink M1 was prepared by adjusting the mixing ratio of citric acid and sodium citrate as shown in Table 1. The viscosity of the ink was measured using a rotational viscometer with a thermostat (manufactured by Toki Sangyo Co., Ltd .: VISCOMETER TV-33, VISCOMATE VM-150III). The viscosity at 1 minute after the start of the measurement was measured.

(Black ink K1)
In the preparation of the magenta ink M1, C.I. I. Reactive Red 218 (10 parts by mass) to C.I. I. It changed into reactive black 39 (14 mass parts). Ink compositions other than reactive dyes were prepared in the same manner as magenta ink M1.

<Preparation of ink sets 2 to 7>
Ink set 1 except that the type of reactive dye and the type / addition amount of the buffer were changed as shown in Table 1 and the mixing ratio of the buffer components was adjusted so that the pH of the ink was shown in Table 1. Similarly, ink sets 2 to 7 were prepared.

<Inkjet printer>
As an ink jet printer, Nassenger VII (manufactured by Konica Minolta IJ) was used.

<Pretreatment process>
Cotton broad was prepared as a cotton fabric, the following pretreatment agent was applied at a drawing rate of 70%, and then dried at 50 ° C.
(Pretreatment agent)
Carboxymethylcellulose (CMC Daicel 4830, manufactured by Daicel Finechem) 4 parts by weight Urea 5 parts by weight Sodium hydrogen carbonate 5 parts by weight Sodium m-nitrobenzenesulfonate 1 part by weight Ion-exchanged water 85 parts by weight

<Image forming process>
Using the printers set with ink sets 1 to 7, respectively, Y, M, C, K, B, G, R and mixed K (Y, M, C, K 100% each) in the maximum density Multiple images were formed. The formed image is a square image having a side of 30 mm. The fabric on which these images were formed was put in a drier and dried under a blowing drying condition of 70 ° C., and then wound into a roll.

<Coloring process>
The fabric wound up in the form of a roll was steam-treated for 15 minutes under conditions of a relative humidity of 100% and a temperature of 95 ° C. to fix and develop the dye.

<Washing process>
The colored fabric was washed with cold water for 5 minutes and with warm water at 65 ° C. for 5 minutes. Then, it was washed at 85 ° C. using a soaping agent, rinsed again with warm water at 65 ° C. for 5 minutes and with cold water for 5 minutes, and then dried.

<Image evaluation>
(Evaluation of ink storage stability)
Ink sets 1 to 7 were sealed in sealed containers and stored at 40 ° C. for 1 month. The L *, a *, and b * values of the square image formed by the above method were measured using a colorimeter X-Rite 938 using the ink set before and after storage. Add ΔE (ΔE: L * difference, a * difference, b * difference squared to each color image formed using the ink set before and after storage. The square root is taken. Table 2 shows the results of averaging the calculated values of all color images and evaluating them according to the following criteria.
○: ΔE ≦ 2
○ △: 2 <ΔE ≦ 3
Δ: 3 <ΔE ≦ 5
×: ΔE> 5

(Evaluation of image density stability)
The power of the ink jet printer in which each of ink sets 1 to 7 was set was turned on in the morning. Then, image formation was performed at a rate of 45 m ² per day, 5 m ² per hour. After that, the printer was turned off until the next morning. This was continued for 7 days to form a plurality of square images. The brightness (L *) of a total of 14 square images formed at the beginning and end of each day was measured using a colorimeter X-Rite 938, and the variation with respect to the average value of 14 data was calculated. Table 2 shows the results of averaging the calculated values of all color images and evaluating them according to the following criteria.
○: Variation in lightness for one week is within 3% ○ △: Lightness variation in one week is over 3% and within 5% △: Lightness variation in one week is over 5% and within 10% ×: Lightness in one week Variation more than 10%

(Evaluation of image color stability)
The L *, a *, and b * values of the 14 square images used for the above-described density stability evaluation were measured using a colorimeter X-Rite 938. For all square images, ΔE with the first image was calculated, and the maximum value of the calculated ΔE was obtained. Table 2 shows the results obtained by averaging the maximum values of ΔE of the images of all colors and evaluating them according to the following criteria.
○: ΔE ≦ 2
○ △: 2 <ΔE ≦ 3
Δ: 3 <ΔE ≦ 5
×: ΔE> 5

  An ink set containing a cyan ink containing a vinylsulfone reactive dye and a buffer and an ink other than cyan containing a monochlorotriazine reactive dye and a buffer showed good results in all evaluation items. (Examples 1 to 5). In particular, in Example 1, excellent results were obtained for all evaluation items. In contrast to Example 1, in Example 2, the content of the buffer for the cyan ink is the same as the content of the buffer for the ink other than the cyan ink, and it is difficult to suppress decomposition of the reactive dye on the fabric. Further, the pH of the cyan ink is slightly high, and the storage stability of the cyan ink is lowered. Compared to Example 1, Examples 3 and 4 differ in the buffer contained in the cyan ink, the pH of the cyan ink is high, and the storage stability of the cyan ink is lowered. Therefore, the evaluation results of Examples 2, 3 and 4 are lower than those of Example 1. On the other hand, in Example 5, the pH of cyan ink is the same as that of Example 1, but the pH of inks other than cyan ink is high. As a result, the storage stability of inks other than cyan ink is lowered, so the evaluation result of Example 5 is lower than that of Example 1.

  On the other hand, Comparative Example 1 in which the reactive dye of the cyan ink is monochlorotriazine is good in the storage stability of the ink, but is not stable in the density and color tone of the image. This is because the dye contained in the cyan ink is a phthalocyanine-based dye, so that the dyeing property of the cyan ink is low, and the density and color tone of the image vary.

  Moreover, even if it is a cyan ink containing a vinyl sulfone type reactive dye, the comparative example 2 which does not contain a buffering agent is inferior in all evaluation items. This is because the reactive dye is decomposed over time or on the fabric by not containing a buffer.

  According to the present invention, the density of the formed image can be reduced by suppressing the decomposition of the reactive dye contained in the ink after storage or after landing on the fabric, and combining the dyeing properties of the cyan ink and the ink other than the cyan ink. And an inkjet printing method having excellent color tone stability.

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 (6)

  Drop each ink droplet of an ink set including a cyan ink containing at least a vinyl sulfone reactive dye and a buffer and an ink other than a cyan ink containing a monochlorotriazine reactive dye and a buffer from the inkjet recording head. An ink jet textile printing method including a step of discharging onto a fabric.   The inkjet printing method according to claim 1, wherein the content of the buffer in the cyan ink is larger than the content of the buffer in the ink other than the cyan ink.   The inkjet printing method according to claim 1 or 2, wherein the cyan ink has a pH of 2.5 to 5.5.   The inkjet printing method according to any one of claims 1 to 3, wherein the pH of the ink other than the cyan ink is 7 to 9.   The cyan ink contains at least one of a first phosphoric acid, a second phosphoric acid, a third phosphoric acid, acetic acid, oxalic acid, boric acid, phthalic acid, or citric acid, or a sodium salt, potassium salt, or ammonium salt thereof. The inkjet printing method according to any one of claims 1 to 4, further comprising: The inkjet printing method according to any one of claims 1 to 5, wherein the content of the buffer in the cyan ink is 0.1 to 2.0 mass% with respect to the whole ink. .

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