JP7751572B2 - Dispersant, colored dispersion, inkjet printing ink, ink set, printed hydrophobic fiber, and method for printing hydrophobic fiber - Google Patents

Description

The present invention relates to a dispersant, a colored dispersion, an ink for inkjet printing, an ink set, printed hydrophobic fibers, and a method for printing hydrophobic fibers.

As information becomes increasingly digitalized, inkjet printing has become widespread as a printing machine for both offices and homes, but in recent years it has also been widely expanded for use in commercial printing, textile printing, and other applications. As the uses of inkjet printing expand, the colorants used in inks have also shifted from traditional water-soluble dyes such as acid dyes and direct dyes to water-insoluble colorants such as disperse dyes and pigments, depending on the application.

Disperse dyes, on the other hand, are widely used in the industrial dyeing of hydrophobic fibers such as polyester. Water-insoluble dyes are dispersed in a dye bath or color paste and used for dyeing. Under high-temperature conditions, the dye penetrates and diffuses into the interior of the fiber, and is dyed through hydrogen bonds and intermolecular forces between the fiber and dye. If the dye's dispersibility, especially at high temperatures, is poor, the dye can aggregate in the high-temperature dye bath, easily causing specks on the fiber (a phenomenon in which poorly dispersed dyes adhere to the fiber in dots during dyeing, causing stains on the dyed item).

Inkjet printing of polyester fibers using disperse dyes is also being carried out (see, for example, Non-Patent Documents 1 and 2). Two practical methods are currently in use: direct printing, in which dye ink is applied (printed) to the fibers and then heat-treated with steaming or other methods to fix the dye; and thermal transfer printing, in which dye ink is applied (printed) to an intermediate recording medium (specialized transfer paper) and then heat is used to sublimate and transfer the dye from the intermediate recording medium to the fibers.

To disperse the colorant dispersion, which is the coloring component of the disperse dye ink used in these printing processes, water-insoluble or poorly soluble disperse dyes are crushed to sizes ranging from several tens of nanometers to submicron sizes using a bead mill or similar device. Then, a dispersant is used to disperse the dyes in an aqueous solvent. A dispersant is necessary to maintain a good dispersion state without the dyes settling or producing foreign matter. In recent years, there has been a strong demand for improved storage stability in inks that use disperse dyes. This requires improved storage stability and ink-forming resistance for the colorant dispersion, which is the coloring component. Ink-forming resistance refers to the significant decrease in dispersion stability caused by the shock of adding a component with a polarity different from that of the colorant dispersion when a component other than the colorant dispersion used in the ink is added to the colorant dispersion.

Anionic dispersants (see, for example, Patent Documents 1 and 2) and ethylene oxide adducts of linear alkyls (see, for example, Patent Document 3) have been used as dispersants for disperse dyes. However, none of these have satisfied the sedimentation stability, storage stability, and ejection stability of ink compositions from printers. Therefore, dispersants such as naphthalenesulfonic acid and ligninsulfonic acid have also been used. These dispersants are reported to be derived from coal-derived compounds such as naphthalene, anthracene, and phenanthrene, or alkylated naphthalene, which have been sulfonated with formaldehyde to form a formalin condensate, which is then polymerized and used as a dispersant.

For example, condensates of naphthalenesulfonic acid and ligninsulfonic acid are good dispersants, but color dispersions and inks containing them can have a distinctive odor. Since sublimation transfer inks are transferred by heat, using such dispersants can sometimes cause odor problems.

One method to solve this problem is to use a dispersant other than a naphthalenesulfonic acid-based dispersant (e.g., Patent Documents 1 and 2). However, as mentioned above, this method is insufficient in terms of storage stability, etc. Therefore, there is a need to remove the odor from naphthalenesulfonic acid-based dispersants.

Japanese Patent Application Publication No. 9-291235 Japanese Patent Application Publication No. 8-333531 Japanese Patent Application Laid-Open No. 2003-246954 Japanese Patent Application Publication No. 8-291266

Journal of the Imaging Society of Japan, Vol. 41, No. 2, pp. 68-74 (2002) Senshoku Keizai Shimbun, January 28, 2004, pp. 18-21

The object of the present invention is to provide a color dispersion liquid having excellent low odor properties, as well as an inkjet printing ink, an ink set, printed hydrophobic fibers, and a method for printing hydrophobic fibers using the same.

After extensive research, the inventors discovered that a dispersant containing a compound represented by the following formula (1), in which the contents of 1-methylnaphthalene and 2-methylnaphthalene are both 50 ppm or less when made into an aqueous solution with a solids concentration of 30% by mass, solves the above-mentioned problems, leading to the present invention.

That is, the present invention relates to 1) to 23).

1)
A dispersant containing a compound represented by the following formula (1), in which the contents of 1-methylnaphthalene and 2-methylnaphthalene are both 50 ppm or less when the dispersant is made into an aqueous solution having a solid content concentration of 30 mass %:
(In formula (1), ^R1 and ^R2 each independently represent an alkyl group having 1 to 8 carbon atoms; n represents an integer of 1 to 500; and M each independently represents hydrogen, a metal ion, or an ammonium ion.)

2)
1) The dispersant according to 1), wherein the content of at least one of the 1-methylnaphthalene and the 2-methylnaphthalene is 20 ppm or less.
3)
A color dispersion comprising the dispersant according to 1) or 2), a water-insoluble colorant, and water.
4)
3) The colored dispersion according to 3), wherein the water-insoluble colorant is a water-insoluble dye.
5)
4) The colored dispersion liquid according to 4), wherein the water-insoluble dye is a disperse dye.
6)
5) The colored dispersion liquid according to 5), wherein the disperse dye is at least one disperse dye selected from the group consisting of disperse dyes having a coumarin skeleton, disperse dyes having an azo skeleton, and disperse dyes having an anthraquinone skeleton.
7)
5) The colored dispersion liquid according to 5), wherein the disperse dye is a disperse dye having a coumarin skeleton.

8)
The colored dispersion liquid according to 6) or 7), wherein the disperse dye having a coumarin skeleton is a disperse dye represented by the following formula (2):
(In formula (2), ^R3 represents a substituent, and m represents an integer of 0 to 3.)

9)
8) The colored dispersion liquid according to 8), wherein the disperse dye represented by the formula (2) is C.I. Disperse Yellow 232.
10)
5) The colored dispersion liquid according to 5), wherein the disperse dye is a disperse dye having an azo skeleton.

11)
10) The colored dispersion liquid according to 10), wherein the disperse dye having an azo skeleton is a disperse dye represented by the following formula (3):
(In formula (3), ^R4 represents a substituent, and n represents an integer of 0 to 6.)

12)
11) The colored dispersion liquid according to 11), wherein the disperse dye represented by the formula (3) is C.I. Disperse Orange 25.
13)
5) The colored dispersion liquid according to 5), wherein the disperse dye is a disperse dye having an anthraquinone skeleton.

14)
13) The colored dispersion liquid according to 13), wherein the disperse dye having an anthraquinone skeleton is a dye represented by the following formula (4):
(In formula (4), ^R5 represents a substituent, and p represents an integer of 0 to 6.)

15)
14) The colored dispersion liquid according to 14), wherein the disperse dye represented by the formula (4) is C.I. Disperse Red 60.
16)
16) The color dispersion according to any one of 3) to 15), further comprising an anionic dispersant.
17)
16) The colored dispersion according to 16), wherein the anionic dispersant is a sodium naphthalene sulfonate formalin condensate.
18)
17) The colored dispersion according to 17), wherein the formalin condensate of sodium naphthalenesulfonate is a formalin condensate of creosote oil sulfonic acid.
19)
19) The color dispersion according to any one of 3) to 18), further comprising a phytosterol compound.
20)
An inkjet printing ink comprising the color dispersion liquid according to any one of 3) to 19).
21)
20) An ink set comprising the ink for ink-jet textile printing according to 20) above and at least one ink selected from the group consisting of a yellow ink, a magenta ink, and a cyan ink.
22)
20) A hydrophobic fiber printed using the inkjet printing ink according to 20) or the ink set according to 21).
23)
20) A method for printing hydrophobic fibers, comprising: step A of depositing ink droplets onto a hydrophobic fiber by an inkjet printer using either the ink for ink-jet printing described in 20) or the ink set described in 21); step B of fixing the water-insoluble colorant in the ink droplets deposited in step A to the fiber by heat; and step C of washing away any unfixed water-insoluble colorant remaining in the fiber.

The present invention provides a colored dispersion liquid with excellent low odor properties, as well as an inkjet printing ink using the same, an ink set, hydrophobic fibers printed using the ink set, and a method for printing hydrophobic fibers.

The present invention is described in detail below.

<Dispersant>
The present invention relates to a dispersant containing the compound represented by formula (1) above, which, when made into an aqueous solution with a solid content of 30% by mass, contains 1-methylnaphthalene and 2-methylnaphthalene in an amount of 50 ppm or less.

In the above formula (1), R ¹ and R ² each independently represent an alkyl group having 1 to 8 carbon atoms. Examples of the alkyl group include linear alkyl groups such as methyl, ethyl, n-propyl, n-butyl, and n-octyl groups; branched alkyl groups such as isopropyl, sec-butyl, and tert-butyl groups; and cyclic alkyl groups such as cyclobutyl and cyclohexyl groups. A linear alkyl group having 1 to 5 carbon atoms is preferred, a linear alkyl group having 1 to 4 carbon atoms is more preferred, and a methyl group is particularly preferred. It is also preferred that both R ¹ and R ² are methyl groups.

In the above formula (1), n represents an integer of 1 to 500, preferably 1 to 300, more preferably 1 to 150, particularly preferably 1 to 100, particularly preferably 1 to 75, extremely preferably 1 to 50, and most preferably 1 to 30.

In the above formula (1), M's each independently represent hydrogen, a metal ion, or an ammonium ion, and may be the same or different. For example, when M is hydrogen, the compound is sulfonic acid (—SO ₃ H).

Examples of the metal ion include sodium ion, potassium ion, calcium ion, magnesium ion, etc., and sodium ion is preferred. When M is a sodium ion, the compound becomes sodium sulfonate ( _--SO.sub.3Na ).

Examples of the ammonium ion include ammonium ion, methylammonium ion, dimethylammonium ion, trimethylammonium ion, tetramethylammonium ion, and tetra-n-butylammonium ion.

The compound represented by formula (1) above may be commercially available or synthesized. Commercially available compounds include, for example, Molwet (registered trademark) D-425 Powder, Molwet (registered trademark) D-400 Powder, and Molwet (registered trademark) D-809 Powder (all manufactured by Lion-Akzo Co., Ltd.), Polity (registered trademark) N-100K (manufactured by Lion Corporation), Supragil (registered trademark) MNS/90, and Supragil (registered trademark) RM/210-EI (all manufactured by Rhodia Nikka Co., Ltd.). The compound represented by formula (1) above can be used alone or in combination.

The method for synthesizing the compound represented by formula (1) above is not particularly limited, but examples include a method comprising the steps of adding formaldehyde to an aromatic compound having a substituent such as a sulfo group, an alkyl group having 1 to 6 carbon atoms, or a salt thereof, and polymerizing the aromatic compound with formaldehyde.

The amount of formaldehyde used is not particularly limited, but can be, for example, 0.5 to 1.5 mol per 1 mol of the aromatic compound having the substituent R ¹ (e.g., methylnaphthalenesulfonic acid) and the aromatic compound having the substituent R ² (e.g., methylnaphthalenesulfonic acid) in total.

The reaction temperature for polymerization using formaldehyde is not particularly limited, but can be, for example, 90 to 100°C. The addition time for formaldehyde is also not particularly limited, but can be, for example, 2 to 3 hours. The reaction time is also not particularly limited, but can be, for example, approximately 10 hours. However, during the polymerization reaction, the raw materials, formaldehyde and aromatic compounds, are included as impurities, causing an odor. Research has shown that among aromatic compounds, methylnaphthalene, and among methylnaphthalenes, 1-methylnaphthalene and 2-methylnaphthalene, have a strong odor. By purifying the dispersant after recovery and removing these odor-causing substances, the dispersant can be made to have low odor in addition to initial dispersibility and storage stability over time.

The method for recovering and purifying the dispersant obtained after the reaction is not particularly limited, but for example, a method of removing unreacted components and solvent under reduced pressure as described in Patent Document 5, etc., or other known purification methods can be used.

The method for obtaining a low-odor dispersant is not particularly limited, but can be any conventional method, such as extraction (e.g., solid-liquid extraction, liquid-liquid extraction, reflux extraction, Soxhlet extraction), or immersion or stirring. These methods can be used alone or in combination, for example, solid-liquid extraction and liquid-liquid extraction can be combined. In such cases, the order of the methods can be determined as desired depending on the extraction efficiency and other objectives. Liquid-liquid extraction accompanied by stirring can also be used to shorten the extraction time.

When performing the liquid-liquid extraction described above, an organic solvent can be used as the extraction solvent. The organic solvent may be either hydrophilic or hydrophobic. Examples of organic solvents include monohydric, dihydric, or polyhydric alcohols and their aqueous solutions; ketones such as acetone and methyl ethyl ketone; esters such as methyl acetate and ethyl acetate; linear ethers such as diethyl ether; saturated or unsaturated hydrocarbons such as pentane and hexane; aromatic hydrocarbons such as benzene and toluene; halogenated hydrocarbons such as dichloromethane, chloroform, dichloroethane, and carbon tetrachloride; carbon dioxide; supercritical carbon dioxide; edible oils such as rapeseed oil and soybean oil; fats and oils such as diacylglycerol (DAG), medium-chain fatty acid oils, squalane, and squalene; or mixtures thereof. Of the above extraction solvents, methyl ethyl ketone is particularly preferred.

The extraction conditions are not particularly limited as long as they allow for sufficient extraction. For example, the amount of solvent used for extraction is preferably 1 to 100 mL per 1 g of dispersant. The extraction time can generally be longer if the solvent is at a low temperature, or shorter if the solvent is at a higher temperature. The extraction operation may also be performed two or more times. Preferred extraction conditions include, for example, performing the extraction three times for 1 to 2 hours at 15 to 40°C.

Since organic solvent usually remains in the dispersant layer after the extraction process, an additional process of removing the solvent under reduced pressure may be performed. The degree and duration of the pressure reduction are not particularly limited, but an example of this is 80 mbar for one hour. This series of operations allows for the production of a dispersant with the odor removed.

A dispersant containing a compound represented by formula (1) above may further contain 1-methylnaphthalene and 2-methylnaphthalene in addition to the compound represented by formula (1). However, from the standpoint of odor reduction, when the dispersant is made into an aqueous solution with a solids concentration of 30% by mass, it is preferable that the contents of 1-methylnaphthalene and 2-methylnaphthalene are both 50 ppm or less by mass, and that the content of at least one of the 1-methylnaphthalene and 2-methylnaphthalene is 20 ppm or less. Furthermore, by reducing the contents of 1-methylnaphthalene and 2-methylnaphthalene in the dispersant, a dispersant with even lower odor can be obtained.

The above dispersant has excellent properties such as low odor, initial dispersibility, and storage stability over time.

<Colored dispersion>
The present invention also includes a color dispersion containing the above dispersant, a water-insoluble colorant, and water.

(Water-insoluble colorant)
The water-insoluble colorant contained in the colored dispersion is not particularly limited as long as it can be used as a water-insoluble colorant. For example, known disperse dyes, oil-soluble dyes, carbon black, organic pigments, etc. can be used, but water-insoluble dyes are preferred, and disperse dyes are most preferred.
The content of the water-insoluble colorant in the color dispersion is preferably 0.1 to 25% by mass, more preferably 0.5 to 20% by mass.

Specifically, C.I. Disperse Yellow 3, 4, 5, 7, 8, 9, 13, 23, 24, 30, 33, 34, 39, 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, 114, 116, 11 8, 119, 122, 124, 126, 135, 140, 141, 149, 160, 162, 163, 164, 165, 179, 180, 182, 183, 186, 192, 198, 199, 200, 202, 204, 210, 211, 215, 216, 218, 224, 232, 237, C. I. Disperse Orange 1, 1:1, 3, 5, 7, 11, 13, 17, 20, 21, 23, 25, 29, 30, 31, 32, 33, 37, 38, 42, 43, 44, 45, 47, 48, 49, 50, 53, 54 , 55, 56, 57, 58, 59, 61, 66, 71, 73, 76, 78, 80, 86, 89, 90, 91, 93, 96, 97, 118, 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, 55:1, 56, 58, 59, 60, 65, 70, 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, 1 53,154,157,158,159,164,167,169,177,179,181,183,184,185,188,189,190,191,192,200,201,202,203,205,206,207,210,2 21,224,225,227,229,239,240,257,258,277,278,279,281,283,288,298,302,303,310,311,312,320,323,324,328,359,364,C. I. Disperse Violet 1, 4, 8, 11, 17, 23, 26, 27, 28, 29, 31, 33, 35, 36, 38, 40, 43, 46, 48, 50, 51, 52, 56, 57, 59, 61, 63, 69, 77, 97, C. I. Disperse Green 9,C. I. Disperse Brown 1, 2, 4, 9, 13, 19, C. I. Disperse Blue 3, 5, 7, 9, 14, 16, 19, 20, 26, 26:1, 27, 35, 43, 44, 54, 55, 56, 58, 60, 62, 64, 64:1, 71, 72, 72:1, 73, 75, 77, 79, 79:1, 82, 83, 87, 91, 93, 94, 95, 96, 102, 106, 108, 112, 113, 115, 118, 120, 122, 125, 128, 130, 131, 139, 141, 142, 143, 145, 146, 148, 149, 153, 154, 158, 165, 165:1, 165:2, 167, 171, 173, 174, 176, 181, 183, 185, 186, 187, 189, 197, 198, 200, 201, 205, 207, 211, 214, 224, 225, 257, 259 ,266,267,270,281,284,285,287,288,291,293,295,297,301,315,330,333,341,353,354,358,359,360,364,365,366,368,C. I. Disperse Brack 1, 3, 10, 24, C. I. Solvent Yellow 114, C. I. Solvent Orange 60, 67, C. I. Solvent Red 146, C. I. Solvent Blue 36, 63, 83, 105, 111, C. I. Reactive Yellow 2, 3, 18, 81, 84, 85, 95, 99, 102, C. I. Reactive Orange 5, 9, 12, 13, 35, 45, 99, C. I. Reactive Brown 2, 8, 9, 17, 33, C. I. Reactive Red 3, 3:1, 4, 13, 24, 29, 31, 33, 125, 151, 206, 218, 226, C. I. Reactive Violet 1, 24, C. I. Reactive Blue 2, 5, 10, 13, 14, 15, 15:1, 49, 63, 71, 72, 75, 162, 176, C. I. Reactive Green 5, 8, 19, C. I. Reactive Black 1, 8, 23, 39, C. I. Direct Yellow 2, 3, 4, 9, 10, 11, 12, 13, 15, 16, 50, 66, 73, 84, 86, 87, 88, 89, 91, 110, 127, 128, 129, 130, 132, 138, 139, 141, 142, 145, C. I. Direct Orange 20, 25, 35, 38, 39, 41, C. I. Direct Brown 187, 195, 196, 202, 208, 209, 210, 213, C. I. Direct Red 76, 88, 89, 92, 101, 209, 220, 222, 224, 225, 226, 227, 234, 235, 238, 240, 243, 245, 247, C. I. Direct Blue 52,55,57,76,80,84,86,87,92,102,105,106,108,110,112,197,199,200,202,205,220,231,233,235,237,238,240,245,248,250,C. I. Examples of suitable dyes include, but are not limited to, C.I. Direct Green 55, 57, 59, 60, 77, 80, 82, and 90, and C.I. Direct Black 12, 19, 20, 22, and 23, 105, 107, 110, 112, 115, 117, 120, 125, 129, 132, 135, and 136.

The pigment is a white or colored powder that is insoluble in water, organic solvents, etc., and includes organic pigments and inorganic pigments. In the present invention, either an organic pigment or an inorganic pigment may be used, but organic pigments are preferred. Specifically, C.I. Pigment Yellow 74, 120, 128, 138, 151, 185, 217, C.I. Pigment Orange 13, 16, 34, 43, C.I. Pigment Red 122, 146, 148, C.I. Pigment Violet 19, 23, C.I. Pigment Blue 15, 15:1, 15:2, 15:3, 15:4, 15:5, 15:6, C.I. Pigment Green 7 and 8.
In the present invention, dyes are more preferred.

The colorants may be in the form of powdered or lumped dry colorants, wet cakes, or slurries. They may contain small amounts of dispersants, such as surfactants, to prevent aggregation of colorant particles during or after colorant synthesis. These commercially available colorants are available in grades for industrial dyeing, resin coloring, ink, toner, and inkjet printing, each with different manufacturing methods, purity, and pigment particle size. Smaller particle sizes are preferred to prevent aggregation after pulverization, and fewer impurities are preferred due to their impact on dispersion stability and ink jetting accuracy. Dyes can be used as black colorants by blending a blue dye primarily with orange and red dyes. Small amounts of other water-insoluble colorants may also be included within the range of color tone adjustment.

The above water-insoluble colorants may be blended together. For example, in preparing black ink, a blue water-insoluble colorant may be primarily blended with an orange water-insoluble colorant and a red water-insoluble colorant to achieve a black color, which can then be used as the black water-insoluble colorant. Furthermore, multiple water-insoluble colorants may be blended together to fine-tune the color tone of, for example, blue, orange, red, violet, or black to a more preferred color tone.

The above disperse dye is preferably at least one disperse dye selected from disperse dyes having a coumarin skeleton, disperse dyes having an azo skeleton, disperse dyes having an anthraquinone skeleton, disperse dyes having a quinophthalone skeleton, and disperse dyes having a thioindigo skeleton, and more preferably at least one disperse dye selected from disperse dyes having a coumarin skeleton, disperse dyes having an azo skeleton, and disperse dyes having an anthraquinone skeleton.

(Disperse dyes having a coumarin skeleton)
A preferred embodiment of the disperse dye is a disperse dye having a coumarin skeleton and represented by the formula (2).

In the above formula (2), R ³ represents a substituent, and m represents an integer of 0 to 3.

In the above formula (2), examples of ^R3 include a hydrogen atom, a cyano group, a nitro group, a hydroxy group, a carboxy group, a sulfo group, a halogen atom, an alkyl group having 1 to 8 carbon atoms, an aromatic hydrocarbon group having 6 to 24 carbon atoms, a heterocyclic group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, etc. The alkyl group having 1 to 8 carbon atoms may be the same as those described in the above formula (1).

The above-mentioned halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms, with chlorine atoms being preferred.

Examples of the aromatic hydrocarbon group having 6 to 24 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, and an anthracenyl group. The aromatic hydrocarbon group having 6 to 24 carbon atoms may further have an optional substituent.

Examples of the heterocyclic group include a thiophenyl group, a furan group, a pyridinyl group, a piperazinyl group, a thiazole group, a thiadiazole group, and an azole group. The heterocyclic group may further have an optional substituent.

The substituted or unsubstituted amino group may be an amino group, a methylamino group, an ethylamino group, a phenylamino group, a dimethylamino group, a diethylamino group, a diphenylamino group, a methylphenylamino group, or the like, with a diethylamino group being preferred. Furthermore, the substituted amino group may further have an optional substituent.

Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, an n-butoxy group, a sec-butoxy group, and a tert-butoxy group. The alkoxy group may further have an optional substituent.

Examples of the aryloxy group include a phenoxy group and a naphthoxy group. The aryloxy group may further have an optional substituent.

In the above formula (2), m is preferably 1 to 3, more preferably 2 to 3, and particularly preferably 2.

It is highly preferred that the disperse dye represented by the above formula (2) is C.I. Disperse Yellow 232.

(Disperse dyes having an azo skeleton)
A preferred embodiment of the disperse dye is a disperse dye having an azo skeleton and represented by the formula (3).

In the above formula (3), R ⁴ represents a substituent, and n represents an integer of 0 to 6.

In the above formula (3), ^R4 may be the same as ^R3 described in the above formula (2), and is preferably a nitro group or a diethylamino group which may have a substituent, and more preferably a diethylamino group having one nitro group or one cyano group as a substituent.

In the above formula (3), n is preferably 1 to 4, more preferably 1 to 3, and particularly preferably 2.

It is highly preferred that the disperse dye represented by the above formula (3) is C.I. Disperse Orange 25.

(Disperse dyes having an anthraquinone skeleton)
A preferred embodiment of the disperse dye is a disperse dye having an anthraquinone skeleton and represented by the formula (4).

In the above formula (4), R ⁵ represents a substituent, and p represents an integer of 0 to 6.

In the above formula (4), R ⁵ may be the same as R ³ described in the above formula (2), and is preferably an amino group, a hydroxy group, or a phenoxy group.

In the above formula (4), p is preferably 1 to 4, more preferably 2 to 4, and particularly preferably 3.

It is highly preferred that the disperse dye represented by the above formula (4) is C.I. Disperse Red 60.

Preferably, the disperse dye used in the colored dispersion is C.I. Disperse Yellow 54, C.I. Disperse Yellow 232, C.I. Disperse Red 60, C.I. Disperse Red 364, C.I. Disperse Orange 25, C.I. Solvent Orange 60, C.I. Disperse Blue 359, or C.I. Disperse Blue 360.

The above colorants can be used alone or in combination, and can be blended according to the purpose.

In the color dispersion, the total content of the dispersant is preferably 1 to 120% by mass, more preferably 10 to 100% by mass, and even more preferably 20 to 80% by mass, relative to the total amount of the water-insoluble colorant. The color dispersion also contains water.

(Other ingredients)
The color dispersion may further contain, as other components, a dispersant other than the dispersant that can be used in combination (hereinafter, sometimes abbreviated as a combined dispersant), and additives such as antiseptics, antifungals, and antifoaming agents, which will be described later.

In the color dispersion, the mass ratio (total amount of dispersant/disperse dye) of the total amount of dispersant (total of dispersant and co-dispersant) to the disperse dye is preferably in the range of 1/10 to 10/1, more preferably 1/5 to 5/1, and even more preferably 1/5 to 3/1. By being within the above range, the effect of improving affinity for both the disperse dye and the solvent is appropriately exerted, and the dispersion stability of the disperse dye tends to be further improved even when exposed to long-term storage at high temperatures.

Furthermore, the total amount of dispersant in the above color dispersion is preferably 1 to 120% by mass, more preferably 10 to 100% by mass, and even more preferably 20 to 80% by mass, relative to the total amount of water-insoluble colorant.

(Dispersants that can be used in combination)
The co-dispersant may be any substance other than the above-mentioned dispersants that can disperse the water-insoluble colorant and the dye contained in the inkjet printing ink. Examples of such substances include known dispersants, surfactants, and resin dispersants. Furthermore, the co-dispersant and the surfactant are simply different names and may actually refer to the same substance. Examples of co-dispersants include anionic dispersants, nonionic dispersants, cationic dispersants, and amphoteric dispersants. These co-dispersants can be used alone or in combination. Among these, at least one dispersant selected from anionic dispersants and nonionic dispersants is preferred, and it is more preferred to include an anionic dispersant. It is particularly preferred to include both an anionic dispersant and a nonionic dispersant.

Preferred examples of the anionic dispersants include polymeric sulfonic acids, preferably formalin condensates of aromatic sulfonic acids, lignin sulfonic acid, formalin condensates of lignin sulfonic acid, or salts thereof, or mixtures thereof (hereinafter, unless otherwise specified, the term "formalin condensates of sulfonic acids" also includes "these salts or mixtures thereof"). Examples of "salts thereof" include sodium salts, potassium salts, lithium salts, and the like. Examples of formalin condensates of aromatic sulfonic acids include creosote oil sulfonic acid; cresol sulfonic acid; phenol sulfonic acid; sodium naphthalene sulfonate such as β-naphthalene sulfonic acid; β-naphthol sulfonic acid; β-naphthalene sulfonic acid and β-naphthol sulfonic acid; cresol sulfonic acid and 2-naphthol-6-sulfonic acid; and lignin sulfonic acid. Among these, sodium naphthalenesulfonate, formalin condensates of creosote oil sulfonic acid, β-naphthalenesulfonic acid, and ligninsulfonic acid are preferred. These are commercially available under various trade names. Examples of such products include Demol N, a formalin condensate of β-naphthalenesulfonic acid; Demol C and the Labelin W series, and the like, as formalin condensates of creosote oil sulfonic acid. Other examples include formalin condensates of methylnaphthalenesulfonic acid and formalin condensates of aromatic sulfonic acids other than those listed above. Examples of formalin condensates of aromatic sulfonic acids other than those listed above include Demol SN-B (all manufactured by Kao Corporation); and the Labelin AN series (all manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) as formalin condensates of methylnaphthalenesulfonic acid. Among these, Demol N, the Labelin AN series, and the Labelin W series are preferred, with Demol N and Labelin W being more preferred, and Labelin W being even more preferred. Examples of lignin sulfonic acids include Vanilex N, Vanilex RN, Vanilex G, and Pearlex DP (all manufactured by Nippon Paper Industries Co., Ltd.). Of these, Vanilex RN, Vanilex N, and Vanilex G are preferred.

Examples of the nonionic dispersants include alkylene oxide adducts of phytosterols, alkylene oxide adducts of cholestanols, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkylamines, glycerin fatty acid esters, oxyethyleneoxypropylene block polymers, and substituted derivatives thereof. Of these, alkylene oxide adducts of phytosterols and alkylene oxide adducts of cholestanol are preferred. As alkylene oxide adducts of phytosterols, C2-C4 alkylene oxide adducts of phytosterols are preferred, and ethylene oxide adducts are more preferred. When used herein, the term "phytosterols" is intended to include both phytosterols and/or hydrogenated phytosterols. For example, examples of ethylene oxide adducts of phytosterols include ethylene oxide adducts of phytosterols and/or ethylene oxide adducts of hydrogenated phytosterols. As alkylene oxide adducts of cholestanols, C2-C4 alkylene oxide adducts of cholestanols are preferred, with ethylene oxide adducts being more preferred. In this specification, the term "cholestanols" is intended to include both cholestanols and/or hydrogenated cholestanols. For example, examples of ethylene oxide adducts of cholestanols include ethylene oxide adducts of cholestanol and/or ethylene oxide adducts of hydrogenated cholestanol. The amount of alkylene oxide (preferably C2-C4 alkylene oxide, more preferably ethylene oxide) added per mole of phytosterols or cholestanols is preferably about 10 to 50 moles, and the HLB is preferably about 13 to 20. Specific examples of these include NIKKOL BPS-20, NIKKOL BPS-30 (ethylene oxide adducts of phytosterols); NIKKOL BPSH-25 (ethylene oxide adducts of hydrogenated phytosterols); and NIKKOL DHC-30 (ethylene oxide adducts of cholestanol).

Examples of the above-mentioned cationic dispersants include aliphatic amine salts, aliphatic quaternary ammonium salts, benzalkonium salts, benzethonium chloride, pyridinium salts, and imidazolinium salts.

Examples of the above-mentioned amphoteric dispersants include carboxybetaines, sulfobetaines, aminocarboxylates, imidazolinium betaine, etc.

The resin dispersant may be a copolymer that can be used as an anionic dispersant. Preferred resin dispersants include copolymers of a compound containing an aromatic hydrocarbon group and (meth)acrylic acid (ester); copolymers of a compound containing an aromatic hydrocarbon group and (meth)acrylic acid (ester) and maleic acid (anhydride); etc. In this specification, "(meth)acrylic acid (ester)" refers to acrylic acid, methacrylic acid, acrylic acid esters, and methacrylic acid esters, while "(maleic anhydride)" refers to maleic acid anhydride and maleic acid, respectively. Preferred copolymers of a compound containing an aromatic hydrocarbon group and (meth)acrylic acid (ester) are copolymers having hydrophilic and hydrophobic moieties in the molecule. When copolymerizing a compound containing an aromatic hydrocarbon group and (meth)acrylic acid (ester), a single compound or multiple compounds can be used. Furthermore, maleic acid (anhydride) can be added during copolymerization to form a copolymer of a compound containing an aromatic hydrocarbon group, (meth)acrylic acid (ester), and maleic acid (anhydride). For the purpose of strengthening the interaction with the dye, it is preferable to use a compound containing an aromatic hydrocarbon group as the hydrophobic portion of the copolymer molecule. The aromatic hydrocarbon group is preferably a phenyl group, a phenylene group, a naphthyl group, or a naphthalene-diyl group, more preferably a phenyl group or a phenylene group, and even more preferably a phenyl group. Specific examples of these copolymers include (α-methyl)styrene-acrylic acid copolymer, (α-methyl)styrene-acrylic acid-acrylic acid ester copolymer, (α-methyl)styrene-methacrylic acid copolymer, (α-methyl)styrene-methacrylic acid-acrylic acid ester copolymer, (α-methyl)styrene-maleic acid (anhydride) copolymer, acrylic acid ester-maleic acid (anhydride) copolymer, (α-methyl)styrene-acrylic acid ester-maleic acid (anhydride) copolymer, acrylic acid ester-allylsulfonic acid ester copolymer, acrylic acid ester-styrene sulfonic acid copolymer, (α-methyl)styrene-methacrylic acid sulfonic acid copolymer, polyester-acrylic acid copolymer, polyester-acrylic acid-acrylic acid ester copolymer, polyester-methacrylic acid copolymer, polyester-methacrylic acid-acrylic acid copolymer; and the like. Among these, compounds containing an aromatic hydrocarbon group are preferred that are styrene. In this specification, (α-methyl)styrene is used to include α-methylstyrene and styrene. Specific examples of these copolymers include JONCRYL 67, 68, 586, 611, 678, 680, 682, 683, and 690 manufactured by BASF Corp. Among these, JONCRYL 68, 678, 682, 683, and 690 are preferred.

Other resin dispersants include block copolymers, random copolymers, and graft copolymers composed of at least two monomers (at least one of which is a hydrophilic or water-soluble monomer) selected from styrene and its derivatives, vinyl naphthalene and its derivatives, aliphatic alcohol esters of α,β-ethylenically unsaturated carboxylic acids, acrylic acid and its derivatives, maleic acid and its derivatives, itaconic acid and its derivatives, fumaric acid and its derivatives, vinyl acetate, vinyl alcohol, vinylpyrrolidone, acrylamide, and its derivatives, and/or salts thereof.

(Inkjet printing ink)
The present invention also includes an inkjet printing ink containing the above-described colorant dispersion. In addition to the above-described colorant dispersion, the inkjet printing ink may contain ink preparation agents as needed. Examples of ink preparation agents include known additives such as water-soluble organic solvents, antiseptics and antifungals, pH adjusters, chelating agents, rust inhibitors, UV absorbers, viscosity adjusters, dye solubilizers, anti-fading agents, surface tension adjusters, defoamers, and water. Of these, the total content of the water-soluble organic solvents is typically 0% to 60%, preferably 5% to 40%, more preferably 10% to 35%, and even more preferably 10% to 20%, based on the total mass of the ink. The total content of ink preparation agents other than the water-soluble organic solvents is typically 0% to 10%, preferably 0.05 to 5%, based on the total mass of the ink.

Examples of water-soluble organic solvents include C1-C4 alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, and tert-butanol; amides such as N,N-dimethylformamide and N,N-dimethylacetamide; heterocyclic ketones such as 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethylimidazolidin-2-one, and 1,3-dimethylhexahydropyrimid-2-one; ketones or ketoalcohols such as acetone, methyl ethyl ketone, and 2-methyl-2-hydroxypentan-4-one; cyclic ethers such as tetrahydrofuran and dioxane; ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,5-pentanediol, 1,2-hexanediol, and 1,6 mono-, oligo-, or polyalkylene glycols or thioglycols having a C2-C6 alkylene unit, such as hexanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and thiodiglycol; polyols (preferably triols) such as glycerin, hexane-1,2,6-triol, and trimethylolpropane; C1-C4 monoalkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether (butyl carbitol), triethylene glycol monomethyl ether, and triethylene glycol monoethyl ether; γ-butyrolactone; and dimethyl sulfoxide.

Water-soluble organic solvents also include, for example, substances that are solid at room temperature. In other words, substances that are solid at room temperature but are water-soluble, and whose aqueous solutions exhibit similar properties to water-soluble organic solvents and can be used with the same expected effects, are considered water-soluble organic solvents in this specification. Examples of such substances include solid polyhydric alcohols, sugars, and amino acids.

Examples of antiseptic and antifungal agents include sodium dehydroacetate, sodium benzoate, sodium pyridinethione-1-oxide, zinc pyridinethione-1-oxide, 1,2-benzisothiazolin-3-one, amine salts of 1-benzisothiazolin-3-one, and Proxel GXL(S) manufactured by Lonza.

Any substance that can control the pH of the ink within the range of 6.0 to 11.0 can be used as a pH adjuster to improve the storage stability of the ink. Examples of pH adjusters include carbonates of Group 1 elements in the periodic table, such as lithium carbonate, sodium carbonate, and potassium carbonate; and aminosulfonic acids, such as taurine.

Examples of chelating agents include disodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, and sodium uracildiacetate.

Examples of rust inhibitors include acid sulfite, sodium thiosulfate, ammonium thioglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite.

Examples of UV absorbers include benzophenone compounds, benzotriazole compounds, cinnamic acid compounds, triazine compounds, and stilbene compounds. Compounds that absorb UV light and emit fluorescence, such as benzoxazole compounds, can also be used.

Viscosity adjusters include water-soluble organic solvents as well as water-soluble polymer compounds, such as polyvinyl alcohol, cellulose derivatives, polyamines, and polyimines.

Dye dissolving agents include, for example, urea, ε-caprolactam, ethylene carbonate, etc.

Anti-fading agents are used to improve the storage stability of images. Various organic and metal complex anti-fading agents can be used. Organic anti-fading agents include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, and heterocycles. Metal complex anti-fading agents include nickel complexes and zinc complexes.

Surface tension adjusters include surfactants. Examples of surfactant types include anionic, cationic, amphoteric, nonionic, silicone-based, and fluorine-based surfactants.

Anionic surfactants include alkyl sulfocarboxylates; α-olefin sulfonates; polyoxyethylene alkyl ether acetates; N-acylamino acids or their salts; N-acylmethyltaurines; alkyl sulfates, polyoxyalkyl ether sulfates; alkyl sulfates, polyoxyethylene alkyl ether phosphates; rosin acid soaps; castor oil sulfates; lauryl alcohol sulfates; alkylphenol phosphates; alkyl phosphates; alkylaryl sulfonates; sulfosuccinates such as diethyl sulfosuccinate, diethylhexyl sulfosuccinate, and dioctyl sulfosuccinate; and others. A wide variety of these surfactants are commercially available. Examples of such surfactants include those manufactured by Lion Corporation under the trade names of Ripearl 835I, 860K, 870P, NTD, and MSC; those manufactured by Adeka Corporation under the trade name of Adekacol EC8600; those manufactured by Kao Corporation under the trade names of Perex OT-P, CS, TA, and TR; those manufactured by New Japan Chemical Co., Ltd. under the trade names of Rikamild ES-100, ES-200, Rikasurf P-10, M-30, M-75, M-300, G-30, and G-600; and those manufactured by Toho Chemical Industry Co., Ltd. under the trade names of Kohakunol L-300, L-40, L-400, and NL-400.

Examples of cationic surfactants include 2-vinylpyridine derivatives and poly(4-vinylpyridine) derivatives.

Examples of amphoteric surfactants include lauryl dimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethyl imidazolinium betaine, coconut oil fatty acid amidopropyl dimethylaminoacetic acid betaine, polyoctyl polyaminoethyl glycine, and imidazoline derivatives.

Examples of nonionic surfactants include sodium naphthalenesulfonate formalin condensate, and formalin condensate of creosote oil sulfonic acid is preferred. Examples of nonionic surfactants include ether-based surfactants such as polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, and polyoxyethylene alkyl ether; ester-based surfactants such as polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, and polyoxyethylene stearate; acetylene glycol (alcohol)-based surfactants such as 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, and 3,5-dimethyl-1-hexyne-3-ol; Surfynol 104, 105, 82, and 465 (trade names) and Olfine STG (trade names) manufactured by Nissin Chemical Co., Ltd.; and polyglycol ether-based surfactants (for example, Tergitol manufactured by SIGMA-ALDRICH). 15-S-7, etc.)

Examples of silicone surfactants include polyether-modified siloxane and polyether-modified polydimethylsiloxane. Specific examples of commercially available products include BYK-347 (polyether-modified siloxane), BYK-345, and BYK-348 (polyether-modified polydimethylsiloxane), all manufactured by BYK-Chemie.

Examples of fluorine-based surfactants include perfluoroalkyl sulfonic acid compounds, perfluoroalkyl carboxylic acid compounds, perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups on the side chain. Specific examples of commercially available products include Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, Capstone FS-30, FS-31 (manufactured by DuPont); PF-151N, PF-154N (manufactured by Omnova).

Examples of antifoaming agents include highly oxidized oil-based, glycerin fatty acid ester-based, fluorine-based, and silicone-based compounds.

The inkjet textile printing ink described above contains water. The water used to prepare the ink is preferably ion-exchanged water, distilled water, or other water with few impurities. The prepared ink can also be subjected to microfiltration using a membrane filter or the like. When using the ink described above as an inkjet ink, it is preferable to perform microfiltration to prevent nozzle clogging and other problems. The pore size of the filter used for microfiltration is typically 1 μm to 0.1 μm, preferably 0.8 μm to 0.1 μm.

The method for preparing the inkjet printing ink is not particularly limited, but examples include a method in which a dispersion solution of a colorant (colored dispersion) is prepared and then an ink preparation agent such as a water-soluble organic solvent is added. Methods for preparing an aqueous dispersion of a colorant (colored dispersion) include known methods such as stirring and mixing the components that make up the dispersion using a sand mill (bead mill), roll mill, ball mill, paint shaker, ultrasonic disperser, microfluidizer, etc. Foaming may occur when preparing the colorant dispersion. For this reason, if necessary, a silicone-based or acetylene alcohol-based defoamer may be added during the preparation of the dispersion. However, since some defoamers inhibit the dispersion and microparticulation of dyes, etc., it is preferable to use one that does not affect the microparticulation or stability of the dispersion. Preferred defoamers include, for example, the Olfine series (SK-14, etc.) manufactured by Nissin Chemical Industry Co., Ltd. and the Surfynol series (104, DF-110D, etc.) manufactured by Air Products Japan Co., Ltd.

The inkjet textile printing ink can be prepared, for example, by adding and mixing the aqueous dispersion (colored dispersion), water-soluble organic solvent, and, if necessary, ink preparation agents. The order in which these are mixed is not particularly limited. These ink preparation agents may be added to the extent that they do not impair the effects of the present invention.

The content of the colorant dispersion (aqueous dispersion) contained in the inkjet textile printing ink is typically 2 to 35%, preferably 3 to 30%, and more preferably 5 to 30%, by mass relative to the total mass of the ink (aqueous ink composition). Similarly, the content of the aqueous organic solvent is typically 10 to 50%, preferably 15 to 50%, more preferably 20 to 50%, and even more preferably 30 to 50%. Similarly, the content of the ink adjusters is typically 0 to 25%, preferably 0.01 to 20%, in total, relative to the total mass of the ink (aqueous ink composition).

In order to ensure high-speed ejection response, the viscosity of the inkjet printing ink at 25°C is preferably approximately 3 to 20 mPa·s when measured using an E-type viscometer. Furthermore, the surface tension is preferably in the range of 20 to 45 mN/m when measured using the plate method. In practice, it is preferable to adjust the physical properties to appropriate values taking into account the ejection volume, response speed, and ink droplet flight characteristics of the printer being used.

(Ink set)
The present invention also includes ink sets containing the ink jet textile printing ink and other inks. The ink set containing the ink jet textile printing ink is preferably an ink set containing the ink jet textile printing ink and an ink of a different color tone, and for example, an ink set containing the ink jet textile printing ink and at least one ink selected from the group consisting of a yellow ink, a magenta ink, and a cyan ink is preferred.

(hydrophobic fiber)
The present invention also encompasses hydrophobic fibers printed using the inkjet printing ink or ink set. Specific examples of hydrophobic resins used in the hydrophobic fibers include polyester, nylon, triacetate, diacetate, polyamide, and other resins, as well as resins containing two or more of these resins. Hydrophobic fibers (fibers containing hydrophobic resins) herein include fibers made of the above resins and blends of these fibers with recycled fibers such as rayon and natural fibers such as cotton, silk, and wool. Some fibers are known to have an ink-receiving layer (bleed-preventing layer), and such fibers can also be used in the above-mentioned printing method. Fibers with ink-receiving layers can be prepared by known methods or are commercially available. The material and structure of the ink-receiving layer are not particularly limited and can be used appropriately depending on the purpose. Specific examples of fabrics made from fibers containing hydrophobic resins include satin, tropical, double pique, and microfiber. Examples of films and sheets containing hydrophobic resins include PET films, PET sheets, hydrophobic resin-coated fabrics, glass, metals, ceramics, etc. "PET" means "polyethylene terephthalate."

(Method for printing hydrophobic fibers)
The hydrophobic fiber printing method is a fiber dyeing method and can be broadly divided into two types. The first method is a fiber dyeing method known as direct printing or direct textile printing. This method is a hydrophobic fiber printing method (textile dyeing method) that includes at least three steps: step A, in which ink droplets are deposited on hydrophobic fibers (fibers containing a hydrophobic resin) using an inkjet printer to form image information such as letters and patterns on the fibers; step B, in which the water-insoluble colorant (dye) in the ink droplets deposited in step A is fixed to the fibers by heat; and step C, in which any unfixed water-insoluble colorant (dye) remaining in the fibers is washed away. Step B is generally performed by known steaming or baking. Examples of steaming include a method of treating fibers with a high-temperature steamer, typically at 170 to 180°C, for typically about 10 minutes, or a method of treating fibers with a high-pressure steamer, typically at 120 to 130°C, for typically about 20 minutes, thereby dyeing the fibers with a water-insoluble colorant (dye). Examples of baking (thermosol) include a method of treating fibers with a water-insoluble colorant (dye), typically at 190 to 210°C, for typically about 60 to 120 seconds. Step C is a step of washing the obtained fibers with warm water and, if necessary, water. The warm water or water used for washing may contain a surfactant. The washed fibers are preferably dried, typically at 50 to 120°C, for 5 to 30 minutes.

The above-mentioned textile printing method may further include a fiber pretreatment step to prevent bleeding and other problems. This pretreatment step may involve applying an aqueous solution containing at least one type of sizing agent, and optionally an alkaline substance, an anti-reducing agent, and a hydrotropic agent, to the fiber before the ink is applied. The pretreatment step preferably involves using an aqueous solution of a pretreatment agent containing at least a sizing agent as the pretreatment liquid, and coating or impregnating the fiber with the pretreatment liquid.

Examples of the adhesive include natural gums such as guar and locust bean, starches, sodium alginate, seaweed such as funori, plant skins such as pectic acid, cellulose derivatives such as methylcellulose, ethylcellulose, hydroxyethylcellulose, and carboxymethylcellulose, processed starches such as carboxymethyl starch, and synthetic glues such as polyvinyl alcohol and polyacrylic esters. Sodium alginate is preferred.

Examples of alkaline substances include alkali metal salts of inorganic or organic acids; alkaline earth metal salts; and compounds that liberate alkali when heated. Inorganic or organic alkali metal hydroxides and alkali metal salts are preferred, including sodium compounds and potassium compounds. Specific examples include alkali metal hydroxides such as sodium hydroxide and calcium hydroxide; alkali metal salts of inorganic compounds such as sodium carbonate, sodium bicarbonate, potassium carbonate, sodium dihydrogen phosphate, disodium hydrogen phosphate, and sodium phosphate; and alkali metal salts of organic compounds such as sodium formate and sodium trichloroacetate. Sodium bicarbonate is preferred.

The above-mentioned anti-reducing agent is preferably sodium meta-nitrobenzenesulfonate. Examples of the hydrotropic agent include urea and ureas such as dimethylurea. Urea is preferred.

The sizing agent, alkaline substance, reduction inhibitor, and hydrotropic agent can each be used as a single compound or in combination with multiple compounds. The mixing ratio of each pretreatment agent in the total mass of the pretreatment liquid is, for example, 0.5-5% sizing agent, 0.5-5% alkaline substance (such as sodium bicarbonate), 0-5% reduction inhibitor (such as sodium meta-nitrobenzenesulfonate), 1-20% hydrotropic agent (such as urea), and the remainder water. The pretreatment agent can be applied to the fibers, for example, by padding. The squeezing rate of padding is preferably approximately 40-90%, more preferably approximately 60-80%.

The second method is known as sublimation transfer printing or sublimation transfer dyeing. In this method, ink droplets are deposited on an intermediate recording medium using an inkjet printer to obtain an intermediate recording medium bearing image information such as characters and designs. The surface of the intermediate recording medium bearing the ink droplets is then brought into contact with a material selected from hydrophobic fibers (fibers containing hydrophobic resins), films, and sheets, and heated to sublimate and transfer the water-insoluble colorant (dye) in the ink droplets deposited on the intermediate recording medium to the fibers. A preferred intermediate recording medium is one in which the water-insoluble colorant (dye) in the ink droplets deposited on the intermediate recording medium does not aggregate on its surface and does not interfere with the sublimation of the dye during sublimation transfer. An example of such an intermediate recording medium is paper with an ink-receiving layer formed on its surface using inorganic fine particles such as silica. Paper specifically designed for inkjet recording can also be used. The heating method used to transfer the recorded image from the intermediate recording medium to the fibers typically involves dry heat treatment at approximately 190-200°C.

The intermediate recording medium is not particularly limited and may be selected from the paper and paperboard varieties and processed products listed in "3. Classification f) Paper and Paperboard Varieties and Processed Products" on pages 28-47 of "Paper, Paperboard, and Pulp Terminology [JIS P 0001:1998 (Confirmed in 2008, Revised March 20, 1998, Published by the Japanese Standards Association)] (Nos. 6001-6284, excluding Nos. 6235 "Oil Resistant," 6263 "Flutes and Corrugated Sheets," 6273 "Pulp Molded Products," 6276 "Carbon Paper," 6277 "Multi-Copy Form Paper," and 6278 "Carbon-Backed Form Paper"); and cellophane (hereinafter, "Paper and Paperboard Varieties and Processed Products; and Cellophane" are referred to as "Paper, etc."). Any of these papers, etc. that can be used for dye sublimation transfer can be used as the intermediate recording medium. As mentioned above, when sublimation transfer is carried out, heat treatment is usually carried out at about 190° C. to 210° C. Therefore, among the above intermediate recording media, those that are stable during heat treatment are preferred.

The above inks can be used in a variety of fields, but are suitable for use as water-based writing inks, water-based printing inks, information recording inks, textile printing, etc., and are particularly preferred for use as inkjet textile printing inks.

According to the present invention, it is possible to expand the color reproduction range compared to conventional ink-jet printing, without using an unlimited number and types of dyes as in conventional printing methods using color pastes or the like.
The inkjet printing ink of the present invention can be used without emitting an unpleasant odor during storage or printing. Furthermore, even after long-term storage, the ink exhibits good storage stability, without causing solid aggregation or precipitation. Furthermore, there is very little change in physical properties such as viscosity and average particle size.
Furthermore, the inkjet printing ink of the present invention not only has excellent color development properties, but also excels in various fastness properties such as light fastness, abrasion fastness, gas fastness, chlorine fastness, sweat fastness, and washing fastness.

The present invention will be described in more detail below with reference to the following examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" means parts by mass and "%" means % by mass.

(Preparation of Dispersant)
A 40% solution of the compound represented by formula (1) shown in Table 1 below was prepared using ion-exchanged water. 300 parts of methyl ethyl ketone was added to 300 parts of the dispersant solution, and the mixture was stirred 20 times in a separatory funnel. The mixture was then left to stand for about 1 hour to separate into an upper layer and a lower layer. The lower layer was recovered, and the same amount of methyl ethyl ketone as the lower layer was added, and the same operation was performed twice. The recovered lower layer was treated in an evaporator at 80 mbar and a water bath temperature of 55°C for 1 hour. The obtained dispersant was diluted with ion-exchanged water to a dry solids mass of 30%, to obtain a dispersant.

(Evaluation of odorous components in dispersants)
The dispersant obtained above was made into an aqueous solution having a solid content concentration of 30 mass %, and the amounts of 1-methylnaphthalene and 2-methylnaphthalene in the aqueous solution were determined by the internal standard method (internal standard substance: n-nonane) using a GC/MS apparatus (GC-2020Plus/GCMS-QP2020 manufactured by Shimadzu Corporation) and a column: HP-5MS (manufactured by Agilen Technologies).

The above dispersants were prepared using Molwet D-425 and Supragil RM/210-EI, respectively, as shown in Table 1 below. As a result, the amount of 1-methylnaphthalene or 2-methylnaphthalene in each dispersant was as shown in Table 1.
The concentration of 1-methylnaphthalene in the 30% Molwet D-425 aqueous solution that had not been prepared as described above was 100 ppm, and the concentration of 2-methylnaphthalene was 100 ppm.
In addition, the concentration of 1-methylnaphthalene in a 30% aqueous solution of Supragil RM/210-EI that had not been prepared as described above was 100 ppm, and the concentration of 2-methylnaphthalene was 100 ppm.

Examples 4 to 16 Preparation of Colored Dispersions 1 to 13 0.2 mm diameter glass beads were added to each of the components listed in Tables 2 to 4 below, and the mixture was dispersed in a sand mill for approximately 15 hours under water cooling. The resulting solution was filtered through glass fiber filter paper GC-50 (manufactured by ADVANTEC Corporation) to obtain colored dispersions each containing 15% water-insoluble colorant (dye). The resulting colored dispersions are designated Dispersions 1 to 13, respectively.

Comparative Examples 1 to 12: Preparation of Colored Dispersions 14 to 25 0.2 mm diameter glass beads were added to each of the components listed in Tables 5 to 7 below, and the mixture was subjected to a dispersion treatment in a sand mill for approximately 15 hours under water cooling. The resulting liquid was filtered through glass fiber filter paper GC-50 (manufactured by ADVANTEC Corporation) to obtain colored dispersions of Preparation Examples 14 to 21, each containing 15% water-insoluble colorant (dye). The resulting colored dispersions are designated as Dispersions 14 to 21, respectively.

The abbreviations in Tables 2 to 7 below have the following meanings, and the numerical values mean "parts by mass": DR60: C.I. Disperse Red 60
DY54:C. I. Disperse Yellow 54
DOr25:C. I. Disperse Orange 25
SOr60:C. I. Solvent Orange 60
DB359:C. I. Disperse Blue 359
DB360:C. I. Disperse Blue 360
DR364:C. I. Disperse Red 364
DY232:C. I. Disperse Yellow 232
Molwet D425: Molwet D-425 powder (manufactured by Lion Akzo Co., Ltd.), containing 55% by mass or more of a compound represented by formula (1), in which R ¹ is CH ₃ , R ² is CH ₃ , n is 1 to 20, and M is Na.
Supragil RM/210-EI: Supragil (registered trademark) RM/210-EI (manufactured by Rhodia Nikka Co., Ltd.), containing 85% by mass or more of a compound represented by formula (1) in which ^R1 is _CH3 , ^R2 is _CH3 , n is 1 to 20, and M is Na. Labelin W40: Labelin W40 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), a formalin condensate of creosote oil sulfonic acid. BPS-30: Nikkol BPS-30 (manufactured by Nikko Chemicals Co., Ltd.), an ethylene oxide adduct of phytosterol. Surfynol 104: Surfynol 104 (manufactured by Air Products Japan Co., Ltd.).
Proxel GXL(S): Proxel GXL(S) (manufactured by Lonza)

<Evaluation of Colored Dispersion>
The colored dispersions 1 to 25 obtained as described above were evaluated for the initial particle size of the dispersion, the particle size over time of the dispersion, the storage stability of the dispersion, and the odor of the dispersion by the evaluation methods described below.

<Initial particle size of dispersion>
Colored dispersions 1 to 25 of the Examples and Comparative Examples in Tables 2 to 7 were each diluted 1000 times, and the volume average particle diameter (D50) was measured using a Microtrac UPA (manufactured by Nikkiso Co., Ltd.), and the resulting value was taken as the initial particle diameter of the dispersion. The evaluation criteria are as follows. Rank 2 or lower means that practical use is extremely difficult.
(Evaluation criteria)
Rank 5: The initial particle size of the dispersion is less than 100 nm.
Rank 4: The initial particle size of the dispersion is 100 nm or more and less than 120 nm.
Rank 3: The initial particle size of the dispersion is 120 nm or more and less than 150 nm.
Rank 2: The initial particle size of the dispersion is 150 nm or more and less than 180 nm.
Rank 1: The initial particle size of the dispersion is 180 nm or more.

<Particle size over time in dispersion liquid>
100 g of each of the colored dispersions 1 to 25 of the examples and comparative examples in Tables 2 to 7 was sealed in a glass bottle and left to stand at 60°C for 14 days. After standing, the colored dispersions 1 to 25 were each diluted 1000 times with water, and the volume average particle diameter (D50) was measured using a Microtrac UPA (manufactured by Nikkiso Co., Ltd.) to determine the particle diameter of the dispersion over time. The evaluation criteria are as follows. Rank 2 or lower means that practical use is extremely difficult.
(Evaluation criteria)
Rank 5: The initial particle size of the dispersion is less than 100 nm.
Rank 4: The initial particle size of the dispersion is 100 nm or more and less than 120 nm.
Rank 3: The initial particle size of the dispersion is 120 nm or more and less than 150 nm.
Rank 2: The initial particle size of the dispersion is 150 nm or more and less than 180 nm.
Rank 1: The initial particle size of the dispersion is 180 nm or more.

<Dispersion storage stability>
Colored Dispersions 1 to 25 of the Examples and Comparative Examples in Tables 2 to 7 were each diluted 6,000 times with acetone, and the absorbance at the maximum absorption wavelengths from 400 nm to 780 nm was measured. Next, 100 g of each of Colored Dispersions 1 to 25 was sealed in a glass bottle and left at 60°C for 14 days. After leaving the solution, the resulting Colored Dispersions 1 to 25 were each diluted 6,000 times with acetone, and the absorbance at the maximum absorption wavelength was similarly measured. The absorbance before leaving the solution was set at 100%, and the absorbance after leaving the solution was calculated, and this value was used to evaluate the storage stability of the dispersion. The evaluation criteria are as follows. Rank 2 or lower indicates that practical use is extremely difficult.
(Evaluation criteria)
Rank 5: The absorbance after standing is 95% or more.
Rank 4: The absorbance after standing is 90% or more and less than 95%.
Rank 3: The absorbance after standing is 80% or more and less than 90%.
Rank 2: The absorbance after standing is 60% or more and less than 80%.
Rank 1: The absorbance after standing is less than 60%.

<Odor of dispersion liquid>
10 mL of each of the colored dispersions obtained above was placed in a 50 mL plastic bottle (Eyeboy wide-mouth bottle, manufactured by AS ONE Corporation), and the odor of the dispersion was evaluated (by 10 evaluators). The evaluation criteria are as follows. Rank 2 or lower means that it is extremely difficult to use in practice.
(Evaluation criteria)
Rank 5: 9 to 10 people feel there is no unpleasant odor Rank 4: 7 to 8 people feel there is no unpleasant odor Rank 3: 5 to 6 people feel there is no unpleasant odor Rank 2: 2 to 4 people feel there is no unpleasant odor Rank 1: 0 to 1 people feel there is no unpleasant odor

The results in Tables 2 to 7 show that the colored dispersion of the present invention is a dispersion with excellent particle size stability over time, storage stability, and odor.

Examples 17 to 29 Preparation of Inks 1 to 13 The components shown in Tables 8 and 9 below were mixed and stirred for 30 minutes to obtain Inks 1 to 13. Each of the resulting inks was filtered through glass fiber filter paper GC-50 (manufactured by ADVANTEC Corporation) to prepare test Inks 1 to 13 for use in inkjet recording, each of which had a water-insoluble colorant (dye) content of 5%.

Comparative Examples 13 to 24: Preparation of Inks 14 to 25 The components shown in Tables 10 and 11 below were mixed and stirred for 30 minutes to obtain Inks 14 to 25. Each of the obtained inks was filtered through glass fiber filter paper GC-50 (manufactured by ADVANTEC Corporation) to prepare test Inks 14 to 25 for use in inkjet recording, each of which had a water-insoluble colorant (dye) content of 5%.

The abbreviations in Tables 8 to 11 below have the following meanings, and the numerical values mean "parts by mass": BYK348: Polyether-modified polydimethylsiloxane BYK-348 (manufactured by BYK-Chemie)
Gly: Glycerin TEGMME: Triethylene glycol monomethyl ether (Tokyo Chemical Industry Co., Ltd.)

Ink evaluation
The ink storage stability and ink odor of inks 1 to 25 obtained as described above were evaluated by the evaluation methods described below.

Ink storage stability
Inks 1 to 25 of the Examples and Comparative Examples in Tables 8 to 11 were each diluted 2000 times with acetone, and the absorbance at the maximum absorption wavelengths from 400 nm to 780 nm was measured. Next, 100 g of each of Inks 1 to 25 was sealed in a glass bottle and left at 60°C for 14 days. After leaving the inks 1 to 25, each of the resulting inks was diluted 2000 times with acetone, and the absorbance at the maximum absorption wavelength was similarly measured. The absorbance before leaving the inks was set at 100%, and the absorbance after leaving the inks was calculated, and this value was used to evaluate the ink storage stability. The evaluation criteria are as follows. Rank 2 or lower indicates that practical use is extremely difficult.
(Evaluation criteria)
Rank 5: The absorbance after standing is 95% or more.
Rank 4: The absorbance after standing is 90% or more and less than 95%.
Rank 3: The absorbance after standing is 80% or more and less than 90%.
Rank 2: The absorbance after standing is 60% or more and less than 80%.
Rank 1: The absorbance after standing is less than 60%.

<Ink odor>
30 mL of the inks 1 to 25 obtained above were placed in 50 mL plastic bottles (Eye-Boy wide-mouth bottles, manufactured by AS ONE Corporation), and the ink odor was evaluated (by 10 evaluators). The evaluation criteria were as follows. Rank 2 or lower means that the ink is extremely difficult to use in practice.
(Evaluation criteria)
Rank 5: 9 to 10 people feel there is no unpleasant odor Rank 4: 7 to 8 people feel there is no unpleasant odor Rank 3: 5 to 6 people feel there is no unpleasant odor Rank 2: 2 to 4 people feel there is no unpleasant odor Rank 1: 0 to 1 people feel there is no unpleasant odor

The results in Tables 8 to 11 show that the inks of the present invention have excellent odor and storage stability.

[Preparation of dyed fabric]
Using inks 1 to 25 of each example and comparative example, a solid pattern was printed on transfer paper, an intermediate recording medium, using an inkjet printer PX-105 (manufactured by Seiko Epson Corporation). The ink-deposited portion of the printed transfer paper was cut to a size of 35 cm x 40 cm. The ink-deposited surface of the cut transfer paper was then superimposed on a polyester cloth (pongee) of the same size, and then heat-treated at 200°C for 60 seconds using a transfer press machine TP-600A2 (manufactured by Taiyo Seiki Co., Ltd.). Sublimation transfer dyeing was performed from the transfer paper to the polyester cloth, and the desired colors were obtained.

The colored dispersion (dispersion composition for ink) and ink (aqueous ink composition) of the present invention have low odor and high storage stability, making them particularly useful as aqueous inkjet inks (especially inkjet textile printing inks).

Claims (23)

A dispersant containing a compound represented by the following formula (1), in which the contents of 1-methylnaphthalene and 2-methylnaphthalene are both 50 ppm or less when the dispersant is made into an aqueous solution having a solid content concentration of 30 mass %:
(In formula (1), ^R1 and ^R2 each independently represent an alkyl group having 1 to 8 carbon atoms; n represents an integer of 1 to 500; and M each independently represents hydrogen, a metal ion, or an ammonium ion.) A dispersant as described in claim 1, wherein the content of at least one of the 1-methylnaphthalene and the 2-methylnaphthalene is 20 ppm or less. A color dispersion comprising the dispersant of claim 1 or 2, a water-insoluble colorant, and water. The colored dispersion described in claim 3, wherein the water-insoluble colorant is a water-insoluble dye. The colored dispersion liquid described in claim 4, wherein the water-insoluble dye is a disperse dye. The colored dispersion liquid described in claim 5, wherein the disperse dye is at least one disperse dye selected from the group consisting of disperse dyes having a coumarin skeleton, disperse dyes having an azo skeleton, and disperse dyes having an anthraquinone skeleton. A colored dispersion liquid as described in claim 5, wherein the disperse dye is a disperse dye having a coumarin skeleton. 8. The colored dispersion liquid according to claim 6, wherein the disperse dye having a coumarin skeleton is a disperse dye represented by the following formula (2):
(In formula (2), ^R3 represents a substituent, and m represents an integer of 0 to 3.) The colored dispersion liquid according to claim 8, wherein the disperse dye represented by the above formula (2) is C.I. Disperse Yellow 232. A colored dispersion liquid as described in claim 5, wherein the disperse dye is a disperse dye having an azo skeleton. The colored dispersion liquid according to claim 10, wherein the disperse dye having an azo skeleton is a disperse dye represented by the following formula (3):
(In formula (3), ^R4 represents a substituent, and n represents an integer of 0 to 6.) The colored dispersion liquid described in claim 11, wherein the disperse dye represented by the above formula (3) is C.I. Disperse Orange 25. The colored dispersion liquid described in claim 5, wherein the disperse dye is a disperse dye having an anthraquinone skeleton. The colored dispersion liquid according to claim 13, wherein the disperse dye having an anthraquinone skeleton is a dye represented by the following formula (4):
(In formula (4), ^R5 represents a substituent, and p represents an integer of 0 to 6.) The colored dispersion liquid described in claim 14, wherein the disperse dye represented by the above formula (4) is C.I. Disperse Red 60. A colored dispersion described in any one of claims 3 to 15, further comprising an anionic dispersant. The color dispersion described in claim 16, wherein the anionic dispersant is a sodium naphthalenesulfonate formalin condensate. The color dispersion described in claim 17, wherein the sodium naphthalene sulfonate formalin condensate is a formalin condensate of creosote oil sulfonic acid. A color dispersion described in any one of claims 3 to 18, further comprising a phytosterol compound. An inkjet printing ink comprising the color dispersion liquid described in any one of claims 3 to 19. An ink set comprising the inkjet printing ink according to claim 20 and at least one ink selected from the group consisting of a yellow ink, a magenta ink, and a cyan ink. Hydrophobic fibers printed using the inkjet printing ink described in claim 20 or the ink set described in claim 21. A method for printing hydrophobic fibers, comprising: step A: using the inkjet printing ink according to claim 20 or the ink set according to claim 21, and depositing ink droplets onto hydrophobic fibers using an inkjet printer; step B: fixing the water-insoluble colorant in the ink droplets deposited in step A to the fibers by heat; and step C: washing away any unfixed water-insoluble colorant remaining in the fibers.