JP2016010931A - Inkjet recording method and ink set - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording method which removes ink adhered to the tip part of a nozzle or its adhered product with a cleaning liquid without impairing storage stability of the ink and improves the injection stability and an ink set.SOLUTION: An inkjet recording method uses an aqueous ink comprising a disperse dye, a resin and water and includes a step of discharging droplets of the aqueous ink from an inkjet recording head to impart onto a recording medium and a step of cleaning the inkjet recording head with a cleaning liquid containing an organic solvent. The average SP value of the organic solvent contained in the aqueous ink is 16 or greater and smaller than 22, and the average SP value of the organic solvent contained in the cleaning liquid is 10 or greater and smaller than 15.

Description

  The present invention relates to an ink jet recording method and an ink set.

  Printing an image by an inkjet method is performed by ejecting fine ink droplets from an inkjet recording head and landing on a recording medium to be printed. The inkjet system has the advantage that its mechanism is relatively simple, inexpensive, and can form a high-definition and high-quality image. Therefore, an inkjet printing method for forming an image on a fabric by the inkjet system has been studied.

  A disperse dye ink is known as an ink-jet ink applicable to an ink-jet textile printing method (for example, Patent Document 1). The disperse dye ink is obtained by dispersing and stabilizing a disperse dye, which is a water-insoluble dye, in water with a disperse resin. Disperse dyes are generally used for dyeing hydrophobic fibers mainly composed of polyester. The dispersion resin usually has moderately hydrophilic anionic functional groups; the anionic functional groups are neutralized with a base or the like so as to be soluble in water.

  In such a disperse dye ink, when water or a solvent component in the ink evaporates, the disperse dye or the disperse resin in the ink is likely to be fixed to the nozzle tip portion of the ink jet recording head and clogged. Such clogging is liable to cause injection defects such as injection bends and missing nozzles, and to cause streaks in the image.

  The fixed matter at the nozzle tip of the ink jet recording head is usually removed by wiping with a cloth or blade soaked with a cleaning liquid. As a cleaning liquid for disperse dye ink, a cleaning liquid containing a silicon-based antifoaming agent and an antifungal agent is known (for example, Patent Document 2). As a cleaning liquid for pigment ink, a cleaning liquid containing water, an alkylene glycol monoalkyl ether, and a polyhydric alcohol compound such as glycerin (for example, Patent Document 3); water and a water-soluble organic solvent having an ether bond; A cleaning liquid (for example, Patent Document 4) containing a basic compound and an antioxidant; and a cleaning liquid (Patent Document 5) containing a solvent having a surface tension of less than 35 mN / m and a basic compound. Are known.

JP 2006-124854 A JP 2000-328093 A Japanese Patent Laid-Open No. 2005-7703 JP 2011-156818 A JP 2009-233911 A

  However, since the cleaning liquid of Patent Document 3 contains an organic solvent having a high SP value as a main component, there is a problem that it is difficult to sufficiently dissolve a fixed substance such as a dispersion resin and the cleaning property is not sufficient. On the other hand, the cleaning liquids of Patent Documents 4 and 5 contain an organic solvent having a low SP value above a certain level, so that a fixed substance such as a dispersion resin can be dissolved, but when the cleaning liquid is mixed with the disperse dye ink, the disperse dye There was a problem that the agglomeration (Ostwald growth) was likely to occur. Although the cleaning liquid of Patent Document 2 has a certain detergency, further improvement in detergency is required.

  As described above, in order to improve the injection stability, the fixed matter at the tip of the nozzle can be sufficiently removed by the cleaning liquid, and when the cleaning liquid and the disperse dye ink are mixed, the Ostwald growth of the disperse dye contained in the ink is performed. It is required not to produce.

  The present invention has been made in view of the above circumstances, and can remove the ink adhering to the nozzle tip portion by the cleaning liquid or its fixed substance without impairing the storage stability of the disperse dye ink, thereby improving the injection stability. It is an object to provide an ink jet recording method and an ink set.

[1] An ink jet recording method using a water-based ink containing a disperse dye, a resin, an organic solvent, and water, wherein the water-based ink droplets are ejected from an ink-jet recording head on a recording medium. And the step of cleaning the inkjet recording head with a cleaning liquid containing an organic solvent, wherein the average SP value of the organic solvent contained in the water-based ink is 16 or more and less than 22, and the cleaning liquid contains The inkjet recording method whose average SP value of the organic solvent contained is 10 or more and less than 15.
[2] The organic solvent contained in the cleaning liquid contains at least one selected from the group consisting of glycol monoalkyl ether, polyhydric alcohol, cyclic amide, lactone, cyclic carbonate, cyclic sulfone, and sulfoxide. Inkjet recording method.
[3] The resin according to [1] or [2], wherein the resin includes an anionic group selected from the group consisting of a carboxyl group, a phosphate group, and a sulfonate group, and has an acid value of 3 to 100 mgKOH / g. Inkjet recording method.
[4] The inkjet recording method according to any one of [1] to [3], wherein the organic solvent contained in the cleaning liquid includes a glycol monoalkyl ether having 4 to 7 carbon atoms.
[5] The inkjet recording method according to any one of [1] to [4], wherein the total content of the organic solvent contained in the cleaning liquid is 10% by mass or more based on the entire cleaning liquid.
[6] Any one of [1] to [5], wherein a difference between an average SP value of the organic solvent contained in the water-based ink and an average SP value of the organic solvent contained in the cleaning liquid is 5.5 or more. Inkjet recording method.
[7] The inkjet recording method according to any one of [1] to [6], wherein the surface tension of at least one organic solvent contained in the cleaning liquid at 25 ° C. is in the range of 25 to 35 mN / m.
[8] The inkjet recording method according to any one of [1] to [7], wherein the recording medium is a fabric.

  [9] An ink set including a disperse dye, a resin, an organic solvent, an aqueous ink containing water, and a cleaning liquid containing an organic solvent, and an average SP value of the organic solvent contained in the aqueous ink Is an ink set in which the average SP value of the organic solvent contained in the cleaning liquid is 10 or more and less than 15.

  According to the present invention, there is provided an ink jet recording method and an ink set that can remove the ink or its fixed matter attached to the nozzle tip portion by a cleaning liquid without impairing the storage stability of the disperse dye ink, and can improve the ejection stability. can do.

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

  As described above, when the water-based ink containing the disperse dye and the resin adheres to the tip portion of the nozzle of the ink jet recording head, clogging or injection bending is likely to occur. In particular, when the moisture or solvent component of the ink adhering to the nozzle tip portion evaporates and the disperse dye or resin in the adhering ink adheres, clogging or ejection bending is more likely to occur. The resin can usually have an anionic functional group neutralized with a base. Since the base that neutralizes the anionic functional group also evaporates in the process of evaporating moisture and solvent components, the resin becomes a free H-type resin insoluble in water, and is more easily fixed.

  On the other hand, there is a method of adding a solvent having a low SP value capable of dissolving a fixed matter such as a resin to the water-based ink itself; specifically, a solvent having an SP value of less than 15. However, since a solvent having an SP value of less than 15 dissolves not only the resin but also the disperse dye, the Ostwald growth of the disperse dye occurs in the water-based ink, and coarse particles are generated, resulting in a decrease in the dispersion stability of the ink. It's easy to do. Therefore, in order not to impair the dispersion stability (storage stability) of the ink, the SP value of the solvent contained in the ink needs to be 16 or more; and the SP value of the solvent contained in the cleaning liquid needs to be less than 15.

  On the other hand, if the SP value of the solvent contained in the cleaning liquid is too low, when the water-based ink and the cleaning liquid are mixed, the disperse dye contained in the water-based ink is dissolved, and Ostwald growth of the disperse dye tends to occur. For example, when the nozzle surface of an ink jet recording head is wiped with an absorbing member impregnated with a cleaning liquid; and when the cleaning liquid is passed through the ink flow path of the ink jet recording head for cleaning, the water-based ink remaining in the head and the cleaning liquid May mix. When the water-based ink and the cleaning liquid are mixed as described above, Ostwald growth of the disperse dye contained in the water-based ink occurs, and clogging is likely to occur. In order to suppress such clogging, the SP value of the solvent contained in the cleaning liquid needs to be 10 or more.

  That is, the ink set of the present invention includes an aqueous ink containing a disperse dye, a resin, an organic solvent, water, and a cleaning liquid containing an organic solvent; the average SP value of the organic solvent contained in the aqueous ink is 16 And the average SP value of the organic solvent contained in the cleaning liquid is 10 or more and less than 15.

The SP value (solubility parameter) in the present invention is a value represented by the square root of molecular cohesive energy. F. It can be calculated by the method described in Fedors, Polymer Engineering Science, 14, p147 (1974). The unit is (MPa) ^1/2 and indicates a value at 25 ° C.

  The average SP value in the present invention is a total value obtained by multiplying the SP value of each organic solvent by the content ratio of the solvent to the whole organic solvent. For example, when the composition of the organic solvent contained in the cleaning liquid is solvent A (SP value 10.9): solvent B (SP value 13.0) = 30: 70 (mass ratio), the organic solvent contained in the cleaning liquid The average SP value is 10.9 × 0.3 + 13.0 × 0.7 = 12.37.

1. Ink Set The ink set of the present invention includes water-based ink and a cleaning liquid.

(1) Water-based ink The water-based ink contains at least a disperse dye, a resin, an organic solvent, and water.

<Disperse dye>
Examples of disperse dyes include
C. I. Disperse Yellow: 3, 4, 5, 7, 9, 13, 23, 24, 30, 33, 34, 42, 44, 49, 50, 51, 54, 56, 58, 60, 63, 64, 66, 68 71, 74, 76, 79, 82, 83, 85, 86, 88, 90, 91, 93, 98, 99, 100, 104, 108, 114, 116, 118, 119, 122, 124, 126, 135 140, 141, 149, 160, 162, 163, 164, 165, 179, 180, 182, 183, 184, 186, 192, 198, 199, 202, 204, 210, 211, 215, 216, 218, 224 227, 231, 232,
C. I. Disperse Orange: 1, 3, 5, 7, 11, 13, 17, 20, 21, 25, 29, 30, 31, 32, 33, 37, 38, 42, 43, 44, 45, 46, 47, 48 49, 50, 53, 54, 55, 56, 57, 58, 59, 61, 66, 71, 73, 76, 78, 80, 89, 90, 91, 93, 96, 97, 119, 127, 130 139, 142,
C. I. Disperse Red: 1, 4, 5, 7, 11, 12, 13, 15, 17, 27, 43, 44, 50, 52, 53, 54, 55, 56, 58, 59, 60, 65, 72, 73 74, 75, 76, 78, 81, 82, 86, 88, 90, 91, 92, 93, 96, 103, 105, 106, 107, 108, 110, 111, 113, 117, 118, 121, 122 126, 127, 128, 131, 132, 134, 135, 137, 143, 145, 146, 151, 152, 153, 154, 157, 159, 164, 167, 169, 177, 179, 181, 183, 184 , 185, 188, 189, 190, 191, 192, 200, 201, 202, 203, 205, 206, 207, 210, 221, 224, 22 5, 227, 229, 239, 240, 257, 258, 277, 278, 279, 281, 288, 298, 302, 303, 310, 311, 312, 320, 324, 328, 337, 343
C. I. Disperse Violet: 1, 4, 8, 23, 26, 27, 28, 31, 33, 35, 36, 38, 40, 43, 46, 48, 50, 51, 52, 56, 57, 59, 61, 63 69, 77,
C. I. Disperse Green 9,
C. I. Disperse Brown: 1, 2, 4, 9, 13, 19
C. I. Disperse Blue: 3, 7, 9, 14, 16, 19, 20, 26, 27, 35, 43, 44, 54, 55, 56, 58, 60, 62, 64, 71, 72, 73, 75, 77 79, 79: 1, 79: 2, 81, 82, 83, 87, 91, 93, 94, 95, 96, 102, 106, 108, 112, 113, 115, 118, 120, 122, 125, 128 , 130, 139, 141, 142, 143, 146, 148, 149, 153, 154, 158, 165, 167, 171, 173, 174, 176, 181, 183, 185, 186, 187, 189, 197, 198 , 200, 201, 205, 207, 211, 214, 224, 225, 257, 259, 267, 268, 270, 281, 284, 285, 287 288, 291, 291: 1, 293, 295, 297, 301, 315, 330, 333, 373
C. I. Disperse Black 1, 3, 10, 24,
Etc. are included.

  The average particle diameter of the disperse dye is preferably 50 to 200 nm, more preferably 130 to 150 nm, from the viewpoint of dispersion stability.

  The content of the disperse dye can be 0.3% by mass or more and 20% by mass or less, and preferably 0.5% by mass or more and 10% by mass or less with respect to the entire ink. When the content of the disperse dye is a certain level or more, the obtained image density can be increased. On the other hand, when the content of the disperse dye is not more than a certain value, the viscosity of the ink does not increase excessively and the ejection stability is not easily impaired.

<Resin>
The resin may be a resin for easily dispersing a water-insoluble disperse dye in water. From the viewpoint of facilitating dispersion of the disperse dye, the resin preferably includes a hydrophilic structural unit (a) having an affinity for water and a hydrophobic structural unit (b) having an affinity for the disperse dye; More preferred is a block copolymer comprising a structural unit (a) and a hydrophobic structural unit (b).

Hydrophilic structural unit (a)
The hydrophilic structural unit (a) is derived from a hydrophilic group-containing monomer. The hydrophilic group contained in the hydrophilic group-containing monomer is preferably an ionic group (dissociable group), more preferably an anionic group, from the viewpoint of stability of the emulsified or dispersed state. Examples of the anionic group include a carboxyl group, a phosphoric acid group, and a sulfonic acid group. From the viewpoint of dispersion stability of the resin in the ink, a carboxyl group is preferable.

  That is, the hydrophilic group-containing monomer is preferably an anionic group-containing monomer; more preferably an anionic group-containing monomer having an anionic group and an ethylenically unsaturated bond. Examples of such hydrophilic group-containing monomers include unsaturated carboxylic acid monomers, unsaturated sulfonic acid monomers, and unsaturated phosphoric acid monomers. One type of hydrophilic group-containing monomer may be used, or two or more types may be used in combination.

  Examples of the unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, 2-methacryloyloxymethyl succinic acid and the like. Examples of unsaturated sulfonic acid monomers include styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, 3-sulfopropyl (meth) acrylate, bis- (3-sulfopropyl) -itaconate, and the like. . Examples of unsaturated phosphoric acid monomers include vinyl phosphonic acid, vinyl phosphate, bis (methacryloxyethyl) phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acrylic acid. Leuoxyethyl phosphate and the like are included. Among these, from the viewpoint of dispersion stability and the like, an unsaturated carboxylic acid monomer is preferable, and acrylic acid and methacrylic acid are more preferable.

  The anionic group in the hydrophilic structural unit (a) is preferably neutralized with a volatilizable base component from the viewpoint of improving the fixing property of the disperse dye. The neutralizing base can be an alkali metal-containing base (eg, sodium hydroxide, potassium hydroxide, etc.) or an amine (eg, ammonia, alkanolamine, alkylamine, etc.). Among these, neutralization with amines having a boiling point of less than 200 ° C. is preferable from the viewpoint of improving image durability.

Hydrophobic structural unit (b)
The hydrophobic structural unit (b) is derived from a hydrophobic group-containing monomer. The hydrophobic group-containing monomer may be vinyl monomers such as styrenes and vinyl esters, (meth) acrylates such as alkyl (1 to 4 carbon) esters of (meth) acrylic acid, and the like. One type of hydrophobic group-containing monomer may be used, or two or more types may be used in combination.

  Examples of styrenes include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, isopropyl styrene, n-butyl styrene, tert-butyl styrene, methoxy styrene, butoxy styrene, acetoxy styrene, chlorostyrene, dichlorostyrene, bromo Styrene, chloromethyl styrene, methyl vinyl benzoate, α-methyl styrene, vinyl naphthalene, and the like are included, and styrene and α-methyl styrene are preferable.

  Examples of vinyl esters include vinyl acetate, vinyl chloroacetate, vinyl propionate, vinyl butyrate, vinyl methoxyacetate, vinyl benzoate and the like, preferably vinyl acetate.

  The (meth) acrylates may preferably be (meth) acrylic acid alkyl esters. The alkyl part of the (meth) acrylic acid alkyl ester is linear or branched; the alkyl part of the (meth) acrylic acid alkyl ester preferably has 1 to 12 carbon atoms, preferably 4 to 8 carbon atoms. Is more preferable. Examples of (meth) acrylic acid alkyl esters include methyl (meth) acrylate, ethyl (meth) acrylate, (iso) propyl (meth) acrylate, (iso or tertiary) butyl (meth) acrylate, benzyl (meth) acrylate Etc.

  Examples of the resin containing the hydrophilic structural unit (a) and the hydrophobic structural unit (b) include a styrene-acrylic acid-acrylic acid alkyl ester copolymer, a styrene-acrylic acid copolymer, and a styrene-maleic acid copolymer. Polymers, styrene-maleic acid-acrylic acid alkyl ester copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylic acid alkyl ester copolymers, and the like are included. Examples of commercially available products include JONCRYL series such as JONCRYL586 (manufactured by BASF), JONCRYL67 (manufactured by BASF), JONCRYL819 (manufactured by BASF), and Disperbyk series manufactured by BYK Chemie.

  The content ratio (molar ratio) between the hydrophilic structural unit (a) and the hydrophobic structural unit (b) is determined from the viewpoint of achieving both dispersion stability and dyeing stability. Hydrophilic structural unit (a): hydrophobic structural unit ( b) = 5: 95 to 50:50 is preferable, and 8:92 to 20:80 is more preferable. If the content ratio of the hydrophilic structural unit (a) is a certain value or more, the dispersion stability is easily improved, and if the content ratio of the hydrophobic structural unit (b) is a certain value or more, the dyeing stability is easily improved.

  The acid value of the resin is preferably 3 to 100 mgKOH / g, and more preferably 5 to 85 mgKOH / g. A resin having an acid value of a certain value or more is likely to have high solubility in water or an organic solvent. In addition, a resin having an acid value of a certain value or more can contain many acidic groups neutralized with a base. Therefore, when the base evaporates as the ink is dried, the solubility of the resin in the organic solvent is reduced, and the resin tends to adhere to the nozzle surface of the inkjet recording head as a precipitate. As described above, the present invention is particularly effective for an ink containing a resin having a certain amount or more of acid groups neutralized with a base. From such a viewpoint, the acid value of the resin is more preferably 50 to 85 mgKOH / g, and further preferably 66 to 85 mgKOH / g. In addition, when the acid value of the resin is below a certain level, the affinity with the surface of the disperse dye having hydrophobicity is hardly impaired.

  The acid value of the resin is the number of milligrams of potassium hydroxide (mg KOH / g) required to neutralize the acidic component contained in 1 g of the resin; it can be measured by acid value measurement according to JIS K 0070.

The acid value according to JIS K0070 can be measured by the following method. That is, 10 g of resin is weighed into a 300 ml Erlenmeyer flask, and about 50 ml of a mixed solvent of ethanol: benzene = 1: 2 is added to dissolve the resin. Subsequently, this solution is titrated with a 0.1 mol / L potassium hydroxide ethanol solution standardized in advance using a phenolphthalein indicator. And the acid value (mgKOH / g) is calculated | required by the following formula (1) from the quantity of the potassium hydroxide ethanol solution used for titration.
If the resin does not dissolve in about 50 ml of a mixed solvent of ethanol: benzene = 1: 2, the same titration is performed using either 50 ml of ethanol or about 50 ml of a mixed solvent of ethanol / pure water = 1: 1. I do.

Formula (1)
A = (B × f × 5.611) / S
(In the formula, A is the acid value of the resin (mgKOH / g), B is the amount (ml) of 0.1 mol / L potassium hydroxide ethanol solution used for titration, and f is 0.1 mol / liter potassium hydroxide ethanol solution. Factor, S is resin mass (g), 5.611 is 1/10 of the formula weight of potassium hydroxide (56.11 / 10))

  The weight average molecular weight of the resin is preferably 3000 to 30000, and more preferably 7000 to 20000. When the weight average molecular weight is 3000 or more, not only the effect of improving the dispersibility of the color material is easily obtained, but also the fixing ability of the ink to the recording medium is easily improved. On the other hand, when the weight average molecular weight (Mw) is 30000 or less, the viscosity of the ink is not excessively increased, and the ejection stability is hardly impaired.

The weight average molecular weight of the resin can be measured using gel permeation chromatography. The measurement conditions can be as follows.
(Measurement condition)
Solvent: Tetrahydrofuran Column: Tosoh TSKgel G4000 + 2500 + 2000HXL
Column temperature: 40 ° C
Injection volume: 100 μl
Detector: RI Model 504 (GL Science Co., Ltd.)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0 ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 100000 to 500-sample calibration curves are used. Thirteen samples are used at approximately equal intervals.

  The glass transition temperature (Tg) of the resin is preferably -30 ° C to 100 ° C, and more preferably -20 ° C to 80 ° C.

  The content of the resin is preferably 0.5% by mass or more and 10% by mass or less, and more preferably 1% by mass or more and 6% by mass or less with respect to the entire ink. When the content of the resin is above a certain level, not only can the dispersibility of the disperse dye be sufficiently improved, but it can also function sufficiently as a binder. That is, an increase in viscosity (decrease in fluidity) after ink landing can be realized quickly, and ink mixing can be suppressed. On the other hand, when the resin content is below a certain level, the viscosity of the ink does not increase excessively, and the injection stability is hardly impaired.

  The disperse dye / resin mass ratio of the disperse dye / resin is preferably 100/150 to 100/15, more preferably 100/100 to 100/20. When the resin is above a certain level, the disperse dye is easily dispersed well. If the resin is below a certain level, the viscosity of the ink will not increase too much.

<Organic solvent>
The organic solvent contained in the water-based ink is a water-soluble organic solvent and can be selected so that the average SP value is in the range of 16 to 22.

Examples of organic solvents contained in water-based ink include
Alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, t-butanol, etc.);
Polyhydric alcohols (eg, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol, etc.);
Amines such as ethanolamine and 2- (dimethylamino) ethanol;
Amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.);
Heterocycles (for example, 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexyl pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, etc.) and the like. These organic solvents may be used alone or in combination of two or more.

  Among these, polyhydric alcohols such as ethylene glycol (SP value: 16.3) and glycerin (SP value: 21.1) are easy to adjust the average SP value of the organic solvent contained in the water-based ink to the above range. It is preferable to contain. The content ratio of the polyhydric alcohol to the whole organic solvent is preferably 70% by mass or more, and more preferably 80% by mass or more.

  The organic solvent contained in the water-based ink may further contain an organic solvent having an average SP value in the above range, for example, an SP value of less than 16 (such as a glycol ether alkyl ether as described later).

  The content of the organic solvent is preferably 10% by mass to 60% by mass and more preferably 20% by mass to 45% by mass with respect to the entire ink. By setting the content of the organic solvent to a certain level or higher, it is possible to increase the moisture retention of the ink and to prevent the ink from drying on the nozzle surface of the inkjet recording head and impairing the ejection stability.

<Other ingredients>
The water-based ink may further contain a surfactant, an antiseptic, an antifungal agent, and the like as necessary.

  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, silicone surfactants, fluorine surfactants and the like are included. The content of the surfactant is preferably adjusted so that the surface tension of the ink is 25 to 60 mN / m. Specifically, it may be about 0.0001 to 5% by mass with respect to the whole ink.

  Examples of preservatives or antifungal agents include aromatic halogen compounds (eg, Preventol CMK), methylene dithiocyanate, halogen-containing nitrogen sulfur compounds, 1,2-benzisothiazolin-3-one (eg, PROXEL GXL), etc. Is included.

<Ink physical properties>
The viscosity at 25 ° C. of the water-based ink is preferably 1 to 40 mPa · s, more preferably 5 to 40 mPa · s, and more preferably 5 to 20 mPa · s from the viewpoint of obtaining the injection stability of the ink. Is more preferable. The viscosity of the ink can be measured with an E-type viscometer at 25 ° C. and 1 rpm.

  The surface tension of the ink at 25 ° C. is preferably 25 to 60 mN / m. When the surface tension is less than 25 mN / m, the wettability of the ink with respect to a recording medium such as a 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 a recording medium such as a cloth is lowered, and the ink penetration force is likely to be lowered.

(2) About washing | cleaning liquid A washing | cleaning liquid contains water and an organic solvent, and may further contain other components, such as an antifungal agent, as needed.

<Organic solvent>
The organic solvent contained in the cleaning liquid is selected so that the average SP value is less than 15 from the viewpoint of dissolving the fixed matter on the nozzle surface of the ink jet recording head; and the disperse dye is not dissolved when mixed with the water-based ink. From the viewpoint, the average SP value can be selected to be 10 or more. That is, the organic solvent contained in the cleaning liquid can be selected so that the average SP value is 10 or more and less than 15, more preferably 10.5 or more and 13 or less, and further preferably 10.6 or more and 12 or less.

  The organic solvent contained in the cleaning liquid preferably contains one or more selected from the group consisting of glycol monoalkyl ether, polyhydric alcohol, cyclic amide, lactone, cyclic carbonate, cyclic sulfone and sulfoxide.

a) Glycol monoalkyl ether The glycol ether alkyl ether may be a monoalkyl ether of glycol. Glycols include diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, and the like; preferably diethylene glycol, triethylene glycol, propylene glycol.

  The SP value of the glycol ether alkyl ether can be adjusted by the carbon number of the main chain portion of the glycol and the carbon number of the alkyl ether portion. From the viewpoint of the viscosity of the organic solvent and the stability of dissolution with water, the total number of carbon atoms of the glycol ether alkyl ether is preferably 4 or more and 10 or less, and more preferably 4 or more and 7 or less.

Examples of glycol ether alkyl ethers include
Diethylene glycol monomethyl ether (11.2), diethylene glycol monoethyl ether (10.9), diethylene glycol monopropyl ether (10.7), diethylene glycol monobutyl ether (10.5); triethylene glycol monomethyl ether (10.8), triethylene glycol Ethylene glycol monoethyl ether (10.6), triethylene glycol monopropyl ether (10.5); tetraethylene glycol monomethyl ether (10.6), tetraethylene glycol monoethyl ether (10.4); propylene glycol monomethyl ether (10.4), propylene glycol monoethyl ether (10.9); dipropylene glycol monomethyl ether (9.6), dipropylene glycol Propyl ether (8.6), and the like. Of these, diethylene glycol monoethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, and propylene glycol monoethyl ether are preferred because they have less odor and good detergency. Numerical values in parentheses represent SP values (the same applies to the following).

b) Polyhydric alcohol The polyhydric alcohol may be selected from compounds having a structure in which two or more hydroxyl groups are substituted on a linear or branched alkylene chain having 4 to 6 carbon atoms. Examples of polyhydric alcohols include 1,4-butanediol (15.0), 1,5-pentanediol (14.2), 1,6-hexanediol (13.5), 1,2-hexanediol (13.4), 2-methyl-2,4-pentanediol (13.1), 3-methyl-1,5-pentanediol (13.4) and the like. Of these, 2-methyl-2,4-pentanediol (13.1) is preferable.

c) Cyclic Amides Examples of cyclic amides include 2-pyrrolidone (12.6), N-methylpyrrolidone (11.5), N-ethylpyrrolidone (11.1), 2-piperidone (12.0), ε -Caprolactam (11.6) etc. are mentioned. Of these, N-methylpyrrolidone is preferable.

d) Lactones Examples of lactones include γ-butyrolactone (10.5), δ-valerolactone (10.2), ε-caprolactone (10.0) and the like. Of these, γ-butyrolactone is preferable.

e) Cyclic carbonates Examples of cyclic carbonates include propylene carbonate (10.5), ethylene carbonate (11.2), and the like. Of these, propylene carbonate is preferred.

f) Cyclic sulfone or sulfoxide Examples of cyclic sulfone or sulfoxide include sulfolane, dimethyl sulfoxide (12.9) and the like. Of these, dimethyl sulfoxide is preferable.

  Among these, glycol monoalkyl ether is preferable from the viewpoint of easy adjustment of the average SP value of the organic solvent contained in the cleaning liquid to the above range, good cleaning properties, and safety and odor. A glycol monoalkyl ether of 10 or less is preferred.

  The content ratio of one or more solvents selected from the group consisting of glycol monoalkyl ethers, polyhydric alcohols, cyclic amides, lactones, cyclic carbonates, cyclic sulfones and sulfoxides to the whole organic solvent is preferably 60% by mass or more, more preferably. May be 80 mass% or more, more preferably 100 mass%.

  The organic solvent contained in the cleaning liquid may further contain another organic solvent as long as the average SP value of the whole organic solvent satisfies the above range.

  In order to suppress the Ostwald growth of the disperse dye contained in the water-based ink when the cleaning liquid and the water-based ink are mixed, the difference between the SP value of the organic solvent in the cleaning liquid and the SP value of the organic solvent in the ink is a certain value or more. Preferably there is. Specifically, the difference between the SP value of the organic solvent in the cleaning liquid and the SP value of the organic solvent in the ink can be 3.0 or more, preferably 5.5 or more.

  At least one of the organic solvents contained in the cleaning liquid; preferably the total surface tension at 25 ° C. is 25 to 35 mN / m. The cleaning liquid containing such an organic solvent tends to have a surface tension of a certain level or less. Therefore, the cleaning liquid easily penetrates into the disperse dye or the fixed substance of the resin, and good cleaning properties are easily obtained.

  Examples of organic solvents having a surface tension of 25 to 35 mN / m at 25 ° C. include diethylene glycol monoethyl ether (31.8), diethylene glycol monobutyl ether (33.6), and dipropylene glycol monomethyl. Alkylene glycol monoethers such as ether (28.8), tripropylene glycol monomethyl ether (30.0), propylene glycol monomethyl ether (27.1); 1,2-hexanediol (28.1), 2- Polyhydric alcohols such as methyl-2,4-pentanediol (27.0) are included. The numerical value in the parenthesis represents the surface tension value (mN / m).

  The surface tension of organic solvents is, for example, New Experimental Chemistry Course Vol. 18 (Interface and Colloid), edited by the Chemical Society of Japan, published by Maruzen Co., Ltd. 68-117 can be referred to and can be measured by a vertical plate method (Wilhelmy method). Specifically, the surface tension of the organic solvent can be measured in a 25 ° C. atmosphere using a surface tension meter CBVP type A-3 (Kyowa Science Co., Ltd.).

  The content ratio of the organic solvent contained in the cleaning liquid may be 3% by mass or more, preferably 5% by mass or more, preferably 10% by mass or more with respect to the entire cleaning liquid. By setting the content ratio of the organic solvent to a certain value or more, the fixed matter on the nozzle surface of the ink jet recording head can be sufficiently dissolved. The content ratio of the organic solvent can be 60% by mass or less with respect to the entire cleaning liquid.

<Other ingredients>
The cleaning liquid may further contain additives such as preservatives and antifungal agents as necessary. Such preservatives and antifungal agents can be the same as the preservatives or antifungal agents that can be included in the aqueous ink described above.

2. Inkjet Recording Method The inkjet recording method of the present invention is an inkjet recording method using the above-described ink set, and 1) a step of ejecting the above-described aqueous ink droplets from an inkjet recording head and applying the droplets to a recording medium; And 2) a step of cleaning the ink jet recording head with the above-described cleaning liquid.

<About step 1)>
Water-based ink droplets are ejected from an inkjet recording head and applied to a recording medium. The recording medium may be heated as necessary to suppress bleeding of the pre-colored image.

  Recording media are plain paper, fabric, inkjet exclusive paper, inkjet glossy paper, cardboard, wood, coated paper such as printing paper, resin base material (for example, polystyrene, acrylonitrile-butadiene-styrene copolymer (ABS resin), vinyl chloride) , Hydrophobic resin base materials such as polyethylene terephthalate (PET)), metal base materials, glass base materials, fabrics, and the like, and preferably fabrics.

  A fabric mainly composed of cellulose fiber, amide fiber, polyester fiber, polyurethane fiber, acrylic fiber, or the like can be used. Specifically, fabrics made of fibers such as cotton, hemp, wool, silk, viscose rayon, cupra rayon, polynosic, vinylon, nylon, acrylic, polyurethane, rayon polyurethane, polyester, acetate, etc. can be used, preferably. Is a fabric mainly composed of polyester fiber. The fibers constituting the fabric may be one type or a combination of two or more types.

  The fabric may be previously treated with a pretreatment agent or the like, as will be described later, from the viewpoint of preventing water-based ink from bleeding and making it easier to obtain a clear image.

<About step 2)>
In the step 2), the above-described cleaning liquid is applied to the inkjet recording head to clean the inkjet recording head. Specifically, the above-described cleaning liquid is applied to the nozzle surface or ink flow path (preferably the nozzle surface) of the ink jet recording head for cleaning. Cleaning with the cleaning liquid may be performed periodically; it may be performed when an injection failure such as nozzle clogging or injection bending occurs. Thereby, the water-based ink adhered to the ink jet recording head or the fixed matter thereof can be satisfactorily removed. The fixed matter of the water-based ink means a material in which at least a part of the water or the solvent component of the water-based ink is evaporated.

  The method of applying the cleaning liquid to the nozzle surface is not particularly limited, but is a method of wiping the absorbing member soaked with the cleaning liquid (for example, a sponge roller or cloth) against the nozzle surface; after spraying the cleaning liquid under liquid pressure And a method of wiping with an absorbing member (cloth or the like); a method of immersing the nozzle surface in a storage tank storing the cleaning liquid and applying vibration. Further, scraping with a blade may be performed before and after the step of applying the cleaning liquid.

  In the present invention, the average SP value of the organic solvent contained in the cleaning liquid is adjusted to be less than 15. Thereby, the fixed matter of the water-based ink adhered to the nozzle surface can be sufficiently dissolved or swollen, and the nozzle surface can be cleaned well.

  Furthermore, the average SP value of the organic solvent contained in the cleaning liquid is adjusted to 10 or more. Thereby, even if the cleaning liquid applied to the nozzle surface or the ink flow path of the ink jet recording head is mixed with the remaining aqueous ink, dissolution of the disperse dye contained in the ink can be suppressed. Thereby, Ostwald growth of the disperse dye can be suppressed, and good injection stability can be maintained. Further, since it is not necessary for the water-based ink itself to contain a solvent having a low average SP value, the dispersion stability (storage stability) of the water-based ink is not impaired.

<About other processes>
The inkjet recording method of the present invention may further include other steps as necessary. For example, when a fabric is used as the recording medium, the inkjet recording method of the present invention may further include 3) a step of applying a pretreatment agent to the fabric (pretreatment step) before the step 1).

<Pretreatment process>
The pretreatment step is a step of treating the fabric with a pretreatment agent in advance in order to prevent ink bleeding on the fabric and obtain a clear image. The pretreatment method is not particularly limited, and a method suitable for the material and ink of the fabric can be appropriately selected from conventionally known methods. For example, a method of applying a pretreatment agent to a fabric by a pad method, a coating method, a spray method or the like can be mentioned. The application amount (squeezing ratio) of the pretreatment agent may be, for example, 0.2% by mass to 90% by mass with respect to the total mass of the fabric, although it depends on the type of fabric and its application.

  The pretreatment agent includes at least one selected from a water-soluble polymer, a water-soluble metal salt, a polycation compound, a surfactant, and a water repellent, preferably a water-soluble polymer.

  The water-soluble polymer can be a natural water-soluble polymer or a synthetic water-soluble polymer. Examples of natural water-soluble polymers include starches such as corn and wheat, cellulose derivatives such as carboxymethylcellulose, methylcellulose and hydroxyethylcellulose; polysaccharides such as sodium alginate, guar gum, tamarind gum, locust bean gum and gum arabic; Protein substances such as gelatin, casein and keratin are included. Examples of the synthetic water-soluble polymer include polyvinyl alcohol, polyvinyl pyrrolidone, acrylic acid polymer and the like.

  Examples of water-soluble metal salts include inorganic salts or organic acid salts such as alkali metals or alkaline earth metals. Examples of the polycation compound include polymers or oligomers of various quaternary ammonium salts, polyamine salts, and the like. Among water-soluble metal salts and polycation compounds, there are those that change the color tone of the fabric or reduce the light fastness, and therefore it is preferable to select them according to the type of the fabric.

  Examples of the surfactant include anionic, cationic, amphoteric and nonionic ones. Examples of anionic surfactants include higher alcohol sulfates and sulfonates of naphthalene derivatives; examples of cationic surfactants include quaternary ammonium salts; amphoteric surfactants Examples of the agent include imidazoline derivatives and the like; examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene propylene block polymer, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, and acetylene alcohol. Ethylene oxide adducts and the like are included.

  Examples of water repellents include silicon water repellents, fluorine water repellents, and wax water repellents.

  These water-soluble polymers and surfactants are preferably stable even in a high-temperature environment so as not to cause tarring or other stains when coloring at high temperature after image formation. In addition, the water-soluble polymer and the surfactant are preferably those that can be easily removed from the fabric by a cleaning treatment after color formation at a high temperature after image formation.

  The pretreatment agent preferably further contains a pH adjusting agent. The pH adjuster is preferably an acid, and specific examples thereof include citric acid, malic acid, tartaric acid and the like. By adding an acid as a pH adjuster to the pretreatment agent, a clear image can be formed at a higher density.

  The pretreatment agent may further contain optional components such as a reduction inhibitor, a chelating agent, a preservative, and a softening agent as necessary. Examples of the reducing agent include sodium m-nitrobenzenesulfonate. Examples of chelating agents include aminopolycarboxylates, hydroxycarboxylates, polycarboxylates, ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid, diethylenetriaminepentaacetic acid, and the like. The preservative may be the same as the preservative exemplified for the ink, or may be the same.

  The inkjet recording method of the present invention may further include a step of fixing the droplets applied on the recording medium in the above 1) to the recording medium. Specifically, it may further include 4) a step of fixing the dye landed on the fabric to the fiber (coloring step); if necessary, 5) a step of removing the dye or pretreatment agent that could not be dyed on the fabric. (Washing step) and 6) a step of drying the washed fabric (drying step) may further be included.

<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, for example, a steaming method, an HT steaming method, an HP 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. Etc., and is appropriately selected depending on textile printing ink, fabric, or the like. For example, the polyester fiber is preferably treated at 160 to 180 ° C. for 5 to 10 minutes when subjected to high temperature steam with an HT steamer; about 30 at 130 to 140 ° C. when subjected to high pressure steam with an HP steamer. It is preferable that the treatment is performed for a minute. 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, soaping method, or the like can be used, and is appropriately selected depending on the type of the ink-jet ink or fabric. For example, a cloth mainly composed of polyester fibers can be generally washed with a mixed solution of caustic soda, a surfactant and hydrosulfite.

<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 recording apparatus>
Hereinafter, an example of an ink jet recording apparatus used in the ink jet recording method will be described.

  FIG. 1 is a partial schematic diagram illustrating an example of the configuration of an inkjet recording apparatus. The ink jet recording apparatus includes a transport unit 2 that transports a fabric, a head carriage 5 that mounts a plurality of ink jet recording heads (not shown) that ejects ink jet ink onto the fabric, and a warm air applying unit 6 that applies warm air to the fabric. And have.

  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 recording apparatus may include an ink control unit (not shown) that controls ejection of each color ink in accordance with set image forming conditions.

  The ink jet recording apparatus preferably further includes a cleaning means (not shown) for cleaning the surface having the nozzle hole portion of the ink jet recording head. As described above, the cleaning unit may be a wipe unit having an ink absorbing member that absorbs ink and a function of supplying a cleaning liquid containing an organic solvent to the ink absorbing member, a blade wipe, or the like. Specific examples of the configuration of the wipe unit include the configuration described in International Publication No. 2012/117742.

  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 the water-based ink droplets described above and landes on a predetermined region (landing possible region) of the fabric to which the pretreatment agent is applied, thereby forming an image. 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.

  Thereafter, while the discharge of the water-based ink is stopped, the nozzle surface is cleaned by the cleaning unit. For example, the nozzle surface of the wipe unit can be cleaned by rubbing the nozzle surface of the recording head with a polyester cloth impregnated with a cleaning liquid.

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

1. Preparation of ink <Ink material>
(Disperse dye)
Y dye: CI Disperse Yellow 114
R dye: CI Disperse Red 343
B dye: CI Disperse Blue 165
C dye: CI Disperse Blue 60

(resin)
Dispersion resin 1: Styrene / (meth) acrylic block copolymer (styrene / butyl acrylate / methyl methacrylate / acrylic acid = 26/16/50/8 molar ratio, weight average molecular weight: 14500, acid value: 75 mgKOH / g)
Dispersing resin 2: Disperbyk-190 (by Big Chemie Japan, acid value 10 mgKOH / g)
Dispersion resin 3: benzyl methacrylate / ethylene oxide / methacrylic acid copolymer (benzyl methacrylate / ethylene oxide / methacrylic acid = 4/60/1 (molar ratio), weight average molecular weight: 3700, acid value: 3 mgKOH / g)

  The acid value and weight average molecular weight of the dispersant were measured by the following methods, respectively.

(Acid value)
The acid value was measured by the following method according to JIS K0070.
10 g of resin was weighed into a 300 ml Erlenmeyer flask, and about 50 ml of a mixed solvent of ethanol: benzene = 1: 2 was added to dissolve the resin. Subsequently, this solution was titrated with a 0.1 mol / L potassium hydroxide ethanol solution standardized in advance using a phenolphthalein indicator. And the acid value (mgKOH / g) was calculated | required by the following formula (1) from the quantity of the potassium hydroxide ethanol solution used for titration.
Formula (1)
A = (B × f × 5.611) / S
(In the formula, A is the acid value of the resin (mgKOH / g), B is the amount (ml) of 0.1 mol / L potassium hydroxide ethanol solution used for titration, and f is 0.1 mol / liter potassium hydroxide ethanol solution. Factor, S is resin mass (g), 5.611 is 1/10 of the formula weight of potassium hydroxide (56.11 / 10))

(Weight average molecular weight)
The weight average molecular weight was measured using gel permeation chromatography. The measurement conditions were as follows.
(Measurement condition)
Solvent: Tetrahydrofuran Column: Tosoh TSKgel G4000 + 2500 + 2000HXL
Column temperature: 40 ° C
Injection volume: 100 μl
Detector: RI Model 504 (GL Science Co., Ltd.)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0 ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 100000 to 500 samples were used. Thirteen samples were used at approximately equal intervals.

(Organic solvent)
DMAE: Dimethylaminoethanol (SP value: 11.3)
DPGPE: Dipropylene glycol monopropyl ether (SP value: 8.6)
EG: ethylene glycol (SP value: 16.3)
DPG: Dipropylene glycol (SP value: 13.3)
Gly: Glycerin (SP value: 21.1)

SP value (solubility parameter) F. The calculation was performed by the method described in Fedors, Polymer Engineering Science, 14, p147 (1974). The unit was (MPa) ^1/2 , and the value at 25 ° C. was used.

(Other ingredients)
Antifungal agent: Proxel GXL (manufactured by Arch Chemical Co., Proxel GXL (S))

(water)
Ion exchange water

<Preparation of ink 1>
Disperse dye Y dye: 2 parts by weight of CI Disperse Yellow 114, R dye: 2 parts by weight of CI Disperse Red 343, B dye: 2 parts by weight of CI Disperse Blue 165 and C dye: 2 parts by weight of CI Disperse Blue 60 2.5 parts by mass of the dispersion resin 1 as a resin, 0.3 parts by mass of DMAE as an organic solvent, 5.0 parts by mass of DPGPE, 25 parts by mass of EG, 10 parts by mass of Gly, 0.25 of Proxel GXL Mass parts and 48.95 parts by mass of ion-exchanged water were added to make the total amount 100 parts by mass. This was put into a bead mill MiniCer manufactured by Ashizawa Finetech, and zirconia beads having a diameter of 0.3 mm were added, and the dispersion was dispersed until the average particle diameter of the disperse dye was within a range of 130 nm to 150 nm. The average particle size of the disperse dye was measured with a Zetasizer 1000 manufactured by Malvern. Thereafter, the zirconia beads were separated by filtration, and the resulting solution was filtered through a 5 μm membrane filter to obtain ink 1.

<Preparation of inks 2 to 6>
Inks 2 to 6 were obtained in the same manner as disperse dye ink 1 except that the ink composition was changed as shown in Table 1.

The compositions of inks 1 to 6 are shown in Table 1.

2. Preparation of cleaning liquid <Material of cleaning liquid>
(Organic solvent)
DEGEE: Diethylene glycol monoethyl ether (SP value: 10.9, surface tension: 31.8)
TEGME: Triethylene glycol monomethyl ether (SP value: 10.8)
TEGEE: Triethylene glycol monoethyl ether (SP value: 10.6)
PGME: Propylene glycol monomethyl ether (SP value: 10.4, surface tension: 27.1)
PGEE: Propylene glycol monoethyl ether (SP value: 10.9)
1,2-HDO: 1,2-hexanediol (SP value: 13.4)
2-Me-2,4-PDO: 2-methyl-2,4-pentanediol (SP value: 13.1, surface tension: 27.0)
3-Me-1,5-PDO: 3-methyl-1,5-pentanediol (SP value: 13.4)
NMP: N-methylpyrrolidone (SP value: 11.5, surface tension: 41.0)
2-PD: 2-pyrrolidone (SP value: 12.6, surface tension: 47.0)
PC: Propylene carbonate (SP value: 10.5)
γBL: γ-butyrolactone (SP value: 10.5, surface tension: 43.9)
DEGBE: Diethylene glycol monobutyl ether (SP value: 10.5)
DMSO: Dimethyl sulfoxide (SP value: 12.9, surface tension: 42.9)
DPGME: Dipropylene glycol monomethyl ether (SP value: 9.6, surface tension: 28.8)
TPGME: Tripropylene glycol monomethyl ether (SP value: 9.1, surface tension: 30.0)
TEGBE: triethylene glycol monobutyl ether (SP value: 9.6, surface tension: 32.1)
DPGPE: Dipropylene glycol monopropyl ether (SP value: 8.6)
EG: ethylene glycol (SP value: 16.3)
Gly: Glycerin (SP value: 21.1)

  The SP value (solubility parameter) is the same as described above for R.P. F. The calculation was performed by the method described in Fedors, Polymer Engineering Science, 14, p147 (1974).

  The surface tension was measured by a vertical plate method (Wilhelmy method) using a surface tension meter CBVP type A-3 (Kyowa Science Co., Ltd.) in an atmosphere at 25 ° C.

(Other ingredients)
Antifungal agent:
Proxel GXL (Arch Chemical Co., Proxel GXL (S))
Antifoam:
FS Anti-Form 92 (made by Dow Corning Asia)

(water)
Ion exchange water

<Preparation of cleaning liquid 1>
Add 0.05 parts by mass of proxel GXL as an antifungal agent, 0.1 parts by mass of FS antifoam 92 as an antifoaming agent, 10 parts by mass of DPGPE (dipropylene glycol monopropyl ether) as an organic solvent, and further add a total amount The ion-exchange water was added and mixed so that it might become 100 mass parts, and the cleaning liquid 1 was obtained.

<Preparation of cleaning liquids 2-28>
Cleaning solutions 2 to 28 were obtained in the same manner as the cleaning solution 1 except that the composition of the cleaning solution was changed as shown in Tables 2 to 4.

The compositions of the cleaning liquids 1 to 28 are shown in Tables 2 to 4.

3. Image Forming Method Using Ink Set (Example 1)
Image streaks, ink storage stability, and miscibility of ink and cleaning liquid were evaluated by the following methods using the ink set of ink 1 and cleaning liquid 7 prepared above.

(Image stripe)
A printer Nassenger-VII manufactured by Konica Minolta was prepared. One recording head of this printer was filled with ink 1, and continuous discharge for 15 minutes was performed for all nozzles (discharge process). Then, it rested for 2 hours. While this ejection was suspended, dry adhesion of the ink adhered to the nozzle surface proceeded. Thereafter, the foaming member containing the cleaning liquid 7 was brought into contact with the nozzle surface of the recording head and reciprocated once to perform wiping (removal step).

  Thereafter, a solid image was formed on a polyester cloth with an appropriate amount of full liquid of 13 pL and a resolution of 540 dpi × 720 dpi. The fabric on which the image was formed was dried with a dryer at 120 ° C. for 5 minutes, then developed with an HT steamer at 175 ° C. for 5 minutes, and subjected to alkali reduction washing to obtain a final printed matter. The image quality of this printed matter was evaluated in five stages from 1 (poor) to 5 (excellent), and 3 or more were judged to be practically acceptable levels. If the inkjet nozzles are not sufficiently cleaned, ejection will be disturbed and appear as streaks in the image.

(Ink storage stability)
The produced ink 1 was stored at 50 ° C. for 2 weeks. And the average particle diameter before a preservation | save and the average particle diameter after a preservation | save were measured, and the change rate of the average particle diameter was calculated | required based on the following formula. The change rate of the average particle diameter was evaluated in 5 stages from 1 (poor) to 5 (excellent), and 3 or more were determined to be practically acceptable levels.
Average particle diameter change rate (%) = {(average particle diameter after storage−average particle diameter before storage) / average particle diameter before storage} × 100

(Mixability of ink and cleaning liquid)
The mixture was mixed so that the mass ratio of ink: cleaning liquid = 90: 10 was obtained. The average particle size of the obtained liquid mixture was measured in the same manner as described above. After this mixed solution was stored at 50 ° C. for 1 week, the average particle size of the mixed solution was measured in the same manner as described above. Then, in the same manner as described above, the change rate of the average particle size before and after storage was determined. The change rate of the average particle diameter was evaluated in 5 stages from 1 (poor) to 5 (excellent), and 3 or more were determined to be practically acceptable levels.

(Examples 2 to 26, Comparative Examples 1 to 9)
The same evaluation as in Example 1 was performed except that the combination of ink and cleaning liquid was changed as shown in Table 5.

Table 5 shows the evaluation results of Examples 1 to 26 and Comparative Examples 1 to 9.

  In Examples 1 to 26 using the ink sets 10 to 34 in which the average SP value of the organic solvent of the ink is 16 or more and less than 22 and the average SP value of the organic solvent of the cleaning liquid is 10 or more and less than 15, the image streak is It can be seen that there is little aggregation of the disperse dye when the ink and the cleaning liquid are mixed.

  On the other hand, it is understood that image streaks occur in Comparative Examples 1 to 6 using the ink sets 1 to 6 in which the average SP value of the organic solvent of the cleaning liquid is less than 10 or 15 or more. This is presumably because the Ostwald growth of the disperse dye occurred due to the mixing of the ink and the cleaning liquid, resulting in clogging. On the other hand, it can be seen that image streaks also occur in Comparative Examples 7 to 9 using the ink sets 7 to 9 in which the average SP value of the organic solvent of the ink is less than 16. This is probably because the SP value of the organic solvent in the cleaning liquids of Comparative Examples 7 to 9 was high, and the dispersion resin contained in the ink could not be sufficiently dissolved and removed.

  From the comparison of Examples 1 to 3 and 6 to 7, it can be seen that when the content ratio of the organic solvent in the cleaning liquid is 10% by mass or more, stable cleaning properties can be obtained and image streaks can be reduced.

  From the comparison between Examples 12 to 16, Examples 6 to 11 and 17 to 23, the average SP value of the organic solvent of the cleaning liquid is set to 11.8 or less, or the ΔSP value is set to 5.5 or more. It can be seen that image streaks can be further reduced.

  From the comparison of Examples 3, 24, and 25, it can be seen that the lower the acid value of the dispersed resin in the ink, the fewer the image streaks. This is presumably because the dispersion resin having a low acid value has few bases that neutralize acidic groups, so that the decrease in the solubility of the resin accompanying the evaporation of the solvent component of the ink is small, and the precipitates are difficult to adhere.

  From the comparison between Example 9 and Example 26, Example 9 using the cleaning liquid 13 containing glycol monoalkyl ether (TEGEE) having 7 or less carbon atoms contains alkyl ether (DEGBE) of glycol having more than 7 carbon atoms. It can be seen that the miscibility is better than that in Example 26 using the cleaning liquid 28. This is presumably because the cleaning solution 13 is less likely to have an excessively low average SP value of the organic solvent when mixed with ink than the cleaning solution 28, and the Ostwald ripening of the disperse dye hardly occurs.

  From the comparison between Examples 10 and 15, Example 10 using the cleaning liquid 14 having a surface tension of 35 mN / m or less has an image streak compared to Example 15 using the cleaning liquid 19 having a surface tension of more than 35 mN / m. It turns out that it is favorable. This is because the cleaning liquid 14 not only has a lower average SP value of the organic solvent than the cleaning liquid 19, but also has a lower surface tension, so that it can easily penetrate the fixed matter on the nozzle surface, and the fixed matter can be removed well. Conceivable.

  According to the present invention, there is provided an ink jet recording method and an ink set that can sufficiently remove the water-based ink adhering to the nozzle tip portion by the cleaning liquid and its fixed matter without impairing the storage stability of the ink, and can improve the ejection stability. can do.

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

Claims (9)

An inkjet recording method using an aqueous ink containing a disperse dye, a resin, an organic solvent, and water,
Discharging the water-based ink droplets from an inkjet recording head and applying the droplets onto a recording medium;
Cleaning the inkjet recording head with a cleaning liquid containing an organic solvent,
The inkjet recording method wherein the average SP value of the organic solvent contained in the water-based ink is 16 or more and less than 22, and the average SP value of the organic solvent contained in the cleaning liquid is 10 or more and less than 15.   2. The inkjet recording according to claim 1, wherein the organic solvent contained in the cleaning liquid includes one or more selected from the group consisting of glycol monoalkyl ether, polyhydric alcohol, cyclic amide, lactone, cyclic carbonate, cyclic sulfone, and sulfoxide. Method.   The ink jet recording method according to claim 1, wherein the resin contains an anionic group selected from the group consisting of a carboxyl group, a phosphoric acid group, and a sulfonic acid group, and has an acid value of 3 to 100 mgKOH / g.   The inkjet recording method according to any one of claims 1 to 3, wherein the organic solvent contained in the cleaning liquid includes a glycol monoalkyl ether having 4 to 7 carbon atoms.   The inkjet recording method according to claim 1, wherein the total content of the organic solvent contained in the cleaning liquid is 10% by mass or more with respect to the entire cleaning liquid.   The inkjet recording according to any one of claims 1 to 5, wherein a difference between an average SP value of the organic solvent contained in the water-based ink and an average SP value of the organic solvent contained in the cleaning liquid is 5.5 or more. Method.   The ink jet recording method according to claim 1, wherein the surface tension of at least one kind of organic solvent contained in the cleaning liquid at 25 ° C. is in the range of 25 to 35 mN / m.   The inkjet recording method according to claim 1, wherein the recording medium is a fabric. An ink set comprising a disperse dye, a resin, an organic solvent, a water-based ink containing water, and a cleaning liquid containing an organic solvent,
The ink set wherein the average SP value of the organic solvent contained in the water-based ink is 16 or more and less than 22, and the average SP value of the organic solvent contained in the cleaning liquid is 10 or more and less than 15.

Images