INK SET FOR INKJET TEXTILE PRINTING AND TEXTILE PRINTING METHOD USING SAME

Abstract

 Provided is an ink set for inkjet printing, which has good light resistance within a magenta-violet-blue hue range. An ink set for inkjet printing according to the present invention comprises two inks, namely a magenta ink and a blue ink, each of which contains at least a dye, water and a water-soluble organic solvent. The magenta ink contains, as a dye, at least a dye represented by formula (1) or a salt thereof. In formula (1), R¹ represents a hydrogen atom or the like; n represents an integer of 2 to 4; X represents NR³R⁴, SR⁵ or OR⁶; each of R³ and R⁴ represents a C2-C6 alkyl group that has a hydroxy group as a substituent, or the like; R⁵ represents a C2-C6 alkyl group that may have a sulfo group as a substituent, or the like; R⁶ represents a hydrogen atom or the like; and R⁷ represents a hydrogen atom or the like.

Description

TECHNICAL FIELD

[0001] The present invention relates to an ink set for inkjet printing and a method of printing a textile using it.

BACKGROUND ART

[0002] A textile inkjet printing using an inkjet printer has a large number of merits: for example, as compared with printing methods such as screen printing, roller printing and rotary printing, plate-making is not necessary, and thus it is possible to reduce a step; it is possible to print a digitalized design through a computer without being processed; it is possible to produce a large number of types of products even by a small amount; and it is possible to significantly reduce the effluent of a coloring matter (dye) color paste and the like. On the other hand, there are problems: for example, as compared with conventional plate-making printing, the print speed is slow; and it is difficult to reproduce a dark color. Hence, inkjet printing is often used in the manufacturing of cut samples and low-volume production.

[0003] In recent years, inkjet printing has been widely used not only because the print speed of an inkjet printer is significantly enhanced by the technical progress of image processing by a computer and print head manufacturing but also because for example, the digitalization of a print design and diverse/small-lot print processing are required in the market.

[0004] As inks for inkjet printing, for example, the following inks are sold: acid dye inks for polyamide-based textiles such as silk and nylon; dispersion dye inks for polyester-based textiles; and reactive dyes (reaction dyes) for cellulose-based textiles such as cotton and rayon.

[0005] In the inkjet printing using the acid dye, an ink set of four colors, that is, black, yellow, magenta (red may be used) and blue (cyan may be used) is normally used. As the performance of the ink used for the inkjet printing, the following are required: it is possible to provide a high-quality, highly robust printed item; and discharge stability is excellent. For these requirements, various inks and ink sets have been proposed. As one of them, there is an ink containing C. I. Acid Blue 112 or C. I. Acid Blue 140. However, various types of robustness for the printed item are required more than before, and in a conventional ink set, there is a problem in which poor light resistance is present in particular in a part where magenta and blue are mixed.

[0006] In inkjet printing, a magenta ink and a blue ink are normally used to reproduce a magenta-violet-blue hue range. It is highly desired from the market to provide an ink set having sufficient light resistance in the hue range described above.

[0007] Patent Document 1 discloses the azo compound represented by formula (1) which will be described later.

[0008] Patent Documents 2 and 3 disclose the ink composition for inkjet printing containing C. I. Acid Blue 112.

[0009] Patent Document 4 discloses the ink composition for inkjet printing containing C. I. Acid Blue 140.

[0010] Patent Document 5 discloses the ink composition for inkjet printing containing C. I. Acid Red 131 which is assumed to be able to obtain satisfactory coloring and satisfactory robustness at the same time.

Patent Document 1: Japanese Unexamined Patent Application (Translation of PCT Application), Publication No. H10-504856

Patent Document 2: Japanese Unexamined Patent Application, Publication No. 2004-210806

Patent Document 3: Japanese Unexamined Patent Application, Publication No. 2007-238798

Patent Document 4: Japanese Unexamined Patent Application, Publication No. 2004-217819

Patent Document 5: Japanese Unexamined Patent Application, Publication No. 2007-031562

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

[0011] An object of the present invention is to provide an ink set for inkjet printing that has satisfactory light resistance in a magenta-violet-blue hue range.

Means for Solving the Problems

[0012] The present inventors and others have studied thoroughly to achieve the above object, with the result that they found that an ink set for inkjet printing which contains a specific coloring matter and which includes an ink of at least two colors, that is magenta and blue, is excellent in light resistance in a magenta-violet-blue hue range, and realized the present invention.

[0013] In other words, the present invention relates to items [1] to [13] below.

[1] An ink set for inkjet printing containing inks of two colors of a magenta ink and a blue ink each of which comprises at least a coloring matter, water and a water-soluble organic solvent,
wherein the magenta ink comprises, as the coloring matter, at least a coloring matter represented by formula (1) below or a salt thereof,

in the formula (1), R¹ is a hydrogen atom or a C1-C6 alkyl group, and
n is an integer of 2 to 4;
X is NR³R⁴, SR⁵ or OR⁶;
R³ and R⁴ are each independently a hydrogen atom; a C1-C6 alkyl group; a C2-C6 alkyl group that has, as a substituent, a hydroxy group, a methoxy group, a carboxy group or a sulfo group; an aralkyl group; or an aryl group that can have, as a substituent, a carboxy group or a sulfo group;
R³ and R⁴ may form a ring that has a heteroatom or no heteroatom;
R⁵ is a C2-C6 alkyl group that can have, as a substituent, a hydroxy group, a methoxy group, a carboxy group or a sulfo group;
R⁶ is a hydrogen atom or a C1-C6 alkyl group; and
R⁷ is a hydrogen atom; a C1-C6 alkyl group; a C2-C6 alkyl group that has, as a substituent, a cyano group, a carboxy group, a hydroxy group, a methoxycarbonyl group, an ethoxycarbonyl group or an acetyl group; or an aryl group that can have, as a substituent, a methyl group or a halogen atom.

[2] The ink set for inkjet printing according to the item [1], where the blue ink comprises, as the coloring matter, an anthraquinone coloring matter.

[3] The ink set for inkjet printing according to the item [2], where the anthraquinone coloring matter is a coloring matter that is selected from C. I. Acid Blue 23, 25, 27, 35, 40, 41, 43, 45, 47, 49, 52, 57, 58, 62, 62:1, 63, 64, 65, 68, 69, 74, 78, 78:1, 79, 80, 81, 81:1, 96, 111, 112, 124, 127, 127:1, 129, 129:1, 138, 138:1, 140, 145, 150, 175, 215, 230, 277, 277:1 and 344.

[4] The ink set for inkjet printing according to any one of the items [1] to [3], where the blue ink comprises, as the coloring matter, at least C. I. Acid Blue 112 or C. I. Acid Blue 140.

[5] The ink set for inkjet printing according to any one of the items [1] to [4], where in the coloring matter represented by the formula (1),
R¹ is a hydrogen atom, and
n is an integer of 2 to 4;
X is NR³R⁴, OR⁶ or SR⁵;
R³ and R⁴ are each independently a hydrogen atom; a C1-C6 alkyl group; or a C2-C6 alkyl group that has, as a substituent, a hydroxy group or a sulfo group;
R⁵ is a C2-C6 alkyl group that can have, as a substituent, a hydroxy group, a carboxy group or a sulfo group;
R⁶ is a hydrogen atom or a C1-C6 alkyl group; and
R⁷ is a hydrogen atom; or a C2-C6 alkyl group that has, as a substituent, a cyano group.

[6] The ink set for inkjet printing according to any one of the items [1] to [5], wherein a total content of the coloring matter in a total mass of each of the magenta ink and the blue ink is 0.5 to 20 mass %.

[7] The ink set for inkjet printing according to any one of the items [1] to [6], wherein the total content of the coloring matter in the total mass of the magenta ink is 2 to 10 mass %, and the total content of the coloring matter in the total mass of the blue ink is 2 to 8 mass %.

[8] The ink set for inkjet printing according to any one of the items [1] to [7], wherein all the coloring matters comprised in the blue ink are C. I. Acid Blue 112 or C. I. Acid Blue 140.

[9] The ink set for inkjet printing according to any one of the items [1] to [8], wherein all the coloring matters comprised in the magenta ink are the coloring matter represented by the formula (1) or the salt thereof.

[10] A textile inkjet printing method that uses the ink set for inkjet printing according to any one of the items [1] to [9] and that sequentially performs at least three steps of steps A to C below:

step A: a step of discharging, in response to a recording signal, a droplet of each ink comprised in the ink set for inkjet printing and attaching the droplet on a textile,

step B: a step of fixing the coloring matter in the droplet of each ink attached in step A on the textile by heat and

step C: a step of washing the coloring matter that is left on the textile and that is not fixed.

[11] The inkjet printing method according to the item [10], wherein the textile is selected from a polyamide fiber and a mixed fiber containing a polyamide fiber.

[12] A textile that is printed by the inkjet printing method according to the item [10] or [11].

[13] The ink set for inkjet printing according to any one of the items [1] to [9], wherein the ink set is used to print a textile that is selected from a polyamide fiber and a mixed fiber containing a polyamide fiber.

Effects of the Invention

[0014] By the ink set for inkjet printing and the inkjet printing method using it according to the present invention, it is possible to obtain a print image excellent in light resistance in a magenta-violet-blue hue range.

PREFERRED MODE FOR CARRYING OUT THE INVENTION

[0015] The present invention will be described in detail below.

[0016] In the present specification including examples, unless otherwise particularly stated, "%" and "parts" are based on mass. Likewise, when a "coloring matter" is simply described, it means both the "coloring matter and its salt."

[0017] In formula (1) described above, examples of the C1-C6 alkyl group include straight-chain, branched and cyclic alkyl groups.

[0018] Specific examples thereof include: straight-chain alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl and n-hexyl groups; branched alkyl groups such as isopropyl, isobutyl, t-butyl, isopentyl, t-pentyl, isohexyl and t-hexyl groups; and cyclic alkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl groups.

[0019] Among them, straight-chain and branched alkyl groups are preferable, and straight-chain alkyl groups are more preferable.

[0020] Examples of the C2-C6 alkyl group include the same groups as in the range of C2-C6 among the C1-C6 alkyl groups described above. Preferable ones and the like are also the same.

[0021] Examples of the aralkyl group preferably include a C6-C12 aryl C1-C10 alkyl group, more preferably include a phenyl C1-C6 alkyl group and further preferably include a phenyl C1-C4 alkyl group (specific examples include: ones in which alkyl parts thereof such as phenyl methyl, 2-phenylethyl, 3-phenylpropyl, 4-phenyl-butyl, 5-phenyl-pentyl, 5-phenyl-hexyl, naphthylmethyl and naphthylethyl are straight-chain; and one in which an alkyl part thereof such as an α-methyl benzyl is branched).

[0022] Examples of the aryl group include: a C6-C10 aryl group; and 5 and 6-membered ring aryl groups in which as ring constituent atoms, one or two nitrogen atoms may be included.

[0023] Specific examples of the former include a phenyl group and a naphthyl group. Among them, a phenyl group is preferable.

[0024] Specific examples of the latter include: 2-, 3- and 4-pyridyl groups in which one nitrogen atom is included; and a pyradyl group, 3- and 4- pyridazinyl groups, and 1-, 4-, and 5-pyrimidinyl groups in which two nitrogen atoms are included.

[0025] Examples of the halogen atom include fluorine atom, chlorine atom, bromine atom, and iodine atom. Among them, fluorine atom and chlorine atom are preferable, and chlorine atom is more preferable.

[0026] When R³ and R⁴ form a ring that includes a heteroatom or no heteroatom, as the former, a ring that includes, as a heteroatom, one nitrogen atom or oxygen atom is preferably formed.

[0027] Specific examples of the former include 1,4-piperazin-1-yl, 4-methyl-piperazin-1-yl and morpholin-4-yl in the form of -NR³R⁴.

[0028] As the latter, in the form of -NR³R⁴, a 5 or 6-membered ring is preferably formed. Specific examples thereof include pyrrolidin-1-yl and piperidin-1-yl.

[0029] Among them, as the coloring matter represented by formula (1), the following coloring matter is preferable
where R¹ is a hydrogen atom,
n is an integer of 2 to 4,
X is NR³R⁴, OR⁶ or SR⁵,
R³ and R⁴ are each independently a hydrogen atom; a C1-C6 alkyl group; a C2-C6 alkyl group having a hydroxy group or a sulfo group as a substituent,
R⁵ is a C2-C6 alkyl group that may have a hydroxy group, a carboxy group or a sulfo group as a substituent,
R⁶ is a hydrogen atom or a C1-C6 alkyl group and
R⁷ is a hydrogen atom or a C2-C6 alkyl group having a cyan group as a substituent. Among them, the following coloring matter is more preferable where
X is NR³R⁴,
R³ and R⁴ are each independently a C2-C6 (preferably C2-C4) alkyl group having a hydroxy as a substituent, and
R⁷ is a hydrogen atom.

[0030] Although specific examples of the coloring matter represented by formula (1) described above are listed in table 1 below, the coloring matter represented by formula (1) is not limited to these specific examples.

[Table 1]

Pigment No.	R1	n	X	R7
1	H	2	-N(CH3)CH2CH2OH	H
2	H	2	-N(CH2CH2OH)2	H
3	H	2	-NHCH2CH2SO3H	H
4	H	2	-S(CH2)3SO3H	H
5	H	2	-SCH2CH2OH	H
6	H	2	-OH	H
7	H	2	-SCH2COOH	H
8	H	2	-OCH2CH3	H
9	H	2	-N(CH3)CH2CH2OH	-CH2CH2CN
10	H	2	-SCH2CH2OH	-CH2CH2CN

[0031] Particularly preferable examples of the coloring matter represented by formula (1) described above include a coloring matter represented by formula (2) below.

[0032] In order to finely adjust the color tone of the ink to the desired color, the magenta ink described above may include a coloring matter other than the coloring matter represented by formula (1) as long as effects obtained by the present invention are not inhibited. It is difficult to unconditionally specify a mixing ratio between the coloring matter represented by formula (1) and the other coloring matter partially because it depends on, for example, the physical properties of the other coloring matter. However, roughly, based on mass, the proportion of the other coloring matter in the total mass of the coloring matters contained in the magenta ink is normally 0 to 50%, is preferably 0 to 25%, is more preferably 0 to 20%, is further preferably 0 to 10% and is particularly preferably 0 to 5%.

[0033] Examples of the other coloring matter that is contained in the ink in order to finely adjust the color tone of the magenta ink described above to the desired color include coloring matters of red colors such as C. I. Acid Red 1, 6, 8, 9, 13, 18, 27, 35, 37, 52, 54, 57, 73, 82, 88, 97, 97:1, 106, 111, 114, 118, 119, 127, 131, 138, 143, 143:1, 145, 151, 183, 195, 198, 211, 215, 217, 225, 226, 249, 251, 254, 256, 257, 260, 261, 265, 266, 274, 276, 277, 289, 296, 299, 315, 318, 336, 337, 357, 359, 361, 362, 364, 366, 399, 407, 415 and 447. Among them, C. I. Acid Red 52, 131, 249, 289 and the like are preferable.

[0034] The coloring matter contained in the blue ink described above is not particularly limited, and a known coloring matter can be used. As the coloring matter, a dye is more preferable than a pigment.

[0035] Examples of the coloring matter contained in the blue ink include coloring matters of blue colors such as C. I. Acid Blue 1, 7, 9, 15, 23, 25, 27, 35, 40, 41, 43, 45, 47, 49, 52, 57, 58, 61:1, 62, 62:1, 63, 64, 65, 68, 69, 72, 74, 78, 78:1, 79, 80, 81, 81:1, 83, 90, 92, 96, 103, 104, 111, 112, 113, 114, 120, 124, 127, 127:1, 128, 129, 129:1, 138, 138:1, 140, 142, 145, 150, 156, 158, 171, 175, 182, 185, 193, 199, 201, 203, 204, 205, 207, 209, 215, 220, 221, 224, 225, 229, 230, 239, 249, 258, 260, 264, 277, 277:1, 278, 279, 280, 284, 290, 296, 298, 300, 317, 324, 333, 335, 338, 342, 344 and 350.

[0036] Among them, the anthraquinone coloring matter is preferable, and a coloring matter is more preferable that is selected from C. I. Acid Blue 23, 25, 27, 35, 40, 41, 43, 45, 47, 49, 52, 57, 58, 62, 62:1, 63, 64, 65, 68, 69, 74, 78, 78:1, 79, 80, 81, 81:1, 96, 111, 112, 124, 127, 127:1, 129, 129:1, 138, 138:1, 140, 145, 150, 175, 215, 230, 277, 277:1 and 344. C. I. Acid Blue 112 (hereinafter referred to as "AB112") or C. I. Acid Blue 140 (hereinafter referred to as "AB140") are particularly preferable.

[0037] In order to finely adjust the color tone of the ink to the desired color, the blue ink described above may include a coloring matter other than AB 112 and AB140 as long as effects obtained by the present invention are not inhibited. It is difficult to unconditionally specify a mixing ratio between AB112 or AB140 and the other coloring matter partially because it depends on, for example, the physical properties of the other coloring matter. However, roughly, based on mass, the proportion of the other coloring matter in the total mass of the coloring matters contained in the blue ink is normally 0 to 50%, is preferably 0 to 25%, is more preferably 0 to 20%, is further preferably 0 to 10% and is particularly preferably 0 to 5%.

[0038] Examples of the other coloring matter that is contained in the ink in order to finely adjust the color tone of the blue ink described above to the desired color include the remaining coloring matters other than AB 112 and AB140 among the coloring matters contained in the blue ink described above.

[0039] Particularly preferably, when light resistance is considered to be important, the other coloring matter is not mixed, and all the coloring matters contained in the magenta ink described above are set to the coloring matter represented by formula (1), and all the coloring matters contained in the blue ink described above are set to AB112 and AB140.

[0040] The total content of the coloring matter of each of the magenta ink and the blue ink described above in the total mass is normally 0.5 to 20%.

[0041] Preferably, the total content of the coloring matter in the total mass of the magenta ink is 2 to 10%, and the total content of the coloring matter in the total mass of the blue ink is 2 to 8%.

[0042] In order to perform full-color printing, the ink set described above may be an ink set of five colors obtained by adding the inks of yellow, cyan and black to the other two colors of the magenta ink and the blue ink. The coloring matters contained in the inks of yellow, cyan and black may be known coloring matters, and are not particularly limited. As the coloring matter, a dye is more preferable than a colorant, and an acid dye is more preferable. When the ink set of the five colors is used, one type of coloring matter contained in the inks of yellow, cyan and black may be used or two or more types may be used together.

[0043] When the ink set of the five colors is used, examples of the coloring matter contained in the yellow ink include coloring matters of yellow colors such as C. I. Acid Yellow 1, 3, 11, 17, 18, 19, 23, 25, 36, 38, 40, 40:1, 42, 44, 49, 59, 59:1, 61, 65, 72, 73, 79, 99, 104, 110, 159, 169, 176, 184, 193, 200, 204, 207, 215, 219, 219:1, 220, 230, 232, 235, 241, 242 and 246. Among them, C. I. Acid Yellow 110 and 79 are preferable.

[0044] When the ink set of the five colors is used, examples of the coloring matter contained in the cyan ink include the same ones as the coloring matters of the blue colors contained in the blue ink described above. Among them, C. I. Direct Blue 86 and 87 are preferable.

[0045] When the cyan ink is used together, the coloring matters contained in the blue ink and the cyan ink are preferably different from each other. When at least one of these inks contains two or more types of coloring matters, at least one of the two or more types of coloring matters is preferably different from the coloring matter contained in the other.

[0046] The total content of the coloring matter in the total mass of the cyan ink is normally 0.5 to 15%, is preferably 1 to 10% and is more preferably 2 to 7.5%.

[0047] When the ink set of the five colors is used, examples of the coloring matter contained in the black ink include coloring matters of black colors such as C. I. Acid Black 1, 2, 3, 24, 24:1, 26, 31, 50, 52, 52:1, 58, 60, 63, 107, 109, 112, 119, 132, 140, 155, 172, 187, 188, 194, 207 and 222. Among them, C. I. Acid Black 52 and 172 are preferable.

[0048] As the black ink described above, a black ink containing coloring matters of three colors, that is, blue, orange and red, a so-called blended black ink, may be used. In order to finely adjust the color tone of the blended black ink to the desired color, another coloring matter may be further contained.

[0049] Examples of the coloring matter of blue colors contained in the blended black ink include the same coloring matters of the blue colors described as the "coloring matters contained in the blue ink."

[0050] Examples of the coloring matter of the orange color contained in the blended black ink described above include C. I. Acid Orange 3, 7, 8, 10, 19, 24, 51, 56, 67, 74, 80, 86, 87, 88, 89, 94, 95, 107, 108, 116, 122, 127, 140, 142, 144, 149, 152, 156, 162, 166 and 168.

[0051] Examples of the coloring matter of the red color contained in the blended black ink described above include the same coloring matters of the red colors described as the "other coloring matter that is contained in the ink in order to finely adjust the color tone of the magenta ink to the desired color."

[0052] Examples of the coloring matter of the other color that is further contained in order to finely adjust the color tone of the blended black ink described above to the desired color include: coloring matters of brown colors such as C. I. Acid Brown 2, 4, 13, 14, 19, 28, 44, 123, 224, 226, 227, 248, 282, 283, 289, 294, 297, 298, 301, 355, 357 and 413; coloring matters of violet colors such as C. I. Acid Violet 17, 19, 21, 42, 43, 47, 48, 49, 54, 66, 78, 90, 97, 102, 109 and 126; and coloring matters of green colors such as C. I. Acid Green 1, 5, 9, 12, 16, 19, 20, 25, 27, 28, 40, 43, 56, 73, 81, 84, 104, 108 and 109.

[0053] The total content of the coloring matter in the total mass of the black ink or the blended black ink is normally 0.5 to 20%, is preferably 2 to 17% and is more preferably 5 to 15%.

[0054] When the blended black ink is used, it is difficult to unconditionally specify the content of each of the coloring matters of blue, orange and red contained the blended black ink because it is varied depending on, for example, the physical properties of the coloring matter used. Roughly, the contents of the coloring matters of blue, orange and red in the total content of the coloring matters contained in the blended black ink are normally 0.2 to 15%, 0.2 to 10% and 0.1 to 10%, respectively, are preferably 1 to 15%, 0.5 to 5% and 0.5 to 5%, respectively and are more preferably 2.5 to 10%, 1.25 to 5% and 1.25 to 5%, respectively.

[0055] In order to express the color tone of a full-color printed item obtained from the ink set of the five colors described above with a wider variety of hue, an ink set of 6 to 16 colors obtained by adding, to the ink set of the five colors described above, an ink which is generally referred to as a "special color" or the like may also be used for printing. Examples of the special color ink include inks of colors such as light blue, light magenta, light yellow, light cyan, light black, orange, golden yellow, red, green, violet and navy.

[0056] With respect to the "light" inks of light blue, light magenta, light yellow, light cyan and light black among the special color inks described above, from among the coloring matters contained in the inks corresponding to the inks of the five colors described above, the coloring matters may be individually selected and contained. Preferably, as these "light" inks, inks in which the same coloring matters as the coloring matters contained in the inks corresponding to the inks of the five colors described above are contained and used with reduced content, respectively. It is difficult to unconditionally specify the contents of the coloring matters contained in these "light" inks because it is varied depending on, for example, the physical properties of the coloring matter used. However, roughly, the content of the coloring matter in the total mass of each of these "light" inks is normally 0.025 to 5%, is preferably 0.05 to 2.5%, and is more preferably 0.05 to 2%.

[0057] However, when in addition to the ink set of the five colors described above, the "light" inks of the corresponding colors are used together, the total content of each of the coloring matters contained in the inks of the ink set of the five colors is more than the total content of the coloring matter contained in the "light" ink of the corresponding color. As an example, when the blue ink and the light blue ink are used together, if the total content of the coloring matter contained in the total mass of the light blue ink is 5%, the lower limit of the total content of the coloring matter contained in the total mass of the blue ink is assumed to be more than 5%.

[0058] Examples of the coloring matter contained in the orange ink among the special color inks described above include the same ones as described in the "coloring matters of the orange colors contained in the blended black ink." Among them, C. I. Acid Orange 33 and 95 are preferable.

[0059] Examples of the coloring matter contained in the golden yellow ink among the special color inks described above include the same ones as described in the "coloring matters contained in the orange ink among the special color inks" and preferable ones. Among them, C. I. Acid Orange 33 and 95 are preferable.

[0060] However, when the orange ink and the golden yellow ink are used together, the coloring matters contained in the orange ink and the golden yellow ink are preferably different from each other. When at least one of these inks contains two or more types of coloring matters, at least one of the two or more types of coloring matters is preferably different from the coloring matter contained in the other.

[0061] Furthermore, examples of the golden yellow ink preferably include a blended ink that contains both at least one type of coloring matter contained in the yellow ink described above and at least one type of coloring matter contained in the orange ink described above. When golden yellow ink is used as the blended ink, examples of the preferable yellow coloring matter include C. I. Acid Yellow 79 and 110. Likewise, examples of the preferable orange coloring matter include C. I. Acid Orange 33 and 95.

[0062] Examples of the coloring matter contained in the red ink among the special color inks described above include the same ones as the coloring matters of the red colors described in the "other coloring matter that is contained in the ink in order to finely adjust the color tone of the magenta ink to the desired color." Among them, C. I. Acid Red 249, 337 and 447 are preferable.

[0063] Examples of the coloring matter contained in the green ink among the special color ink described above include C. I. Acid Green 1, 5, 9, 12, 16, 19, 20, 25, 27, 28, 40, 43, 56, 73, 81, 84, 104, 108 and 109. Among them, C. I. Acid Green 28 is preferable.

[0064] Examples of the coloring matter contained in the violet ink among the special color inks described above include the same ones as the coloring matters of the violet colors described in the "other coloring matter that is contained in order to finely adjust the color tone of the blended black ink to the desired color". Among them, C. I. Acid Violet 48 is preferable.

[0065] Examples of the coloring matter contained in the navy ink among the special color inks described above include the same ones as described in the "coloring matters contained in the blue ink." Among them, C. I. Acid Blue 229 and 300 are preferable.

[0066] As the navy ink described above, a navy ink containing coloring matters of two colors, that is, blue and violet or three colors, that is, blue, violet and black, a so-called blended navy ink, may be used. In order to finely adjust the color tone of the blended navy ink to the desired color, another coloring matter may be further contained.

[0067] Examples of the coloring matter of the blue color contained in the blended navy ink described above include the same ones as the coloring matters of the blue colors described in the "coloring matters contained in the blue ink." Among them, C. I. Acid Blue 112 is preferable.

[0068] Examples of the coloring matter of the violet color contained in the blended navy ink described above include the same ones as the coloring matters of the violet colors described in the "coloring matters contained in the violet ink among the special color inks," including preferable ones.

[0069] Examples of the coloring matter of the black color contained in the blended navy ink described above include the same ones as the coloring matters of the black colors described in the "coloring matters contained in the black ink." Among them, C. I. Acid Black 52 is preferable.

[0070] The total content of the coloring matters in the total mass of the blended navy ink described above is normally 0.5 to 20%, is preferably 2 to 15% and is more preferably 5 to 10%.

[0071] When the blended navy ink described above is used, it is difficult to unconditionally specify the contents of the coloring matters contained in the blended navy ink because it is varied depending on, for example, the physical properties of the coloring matter used. Roughly, the contents of the coloring matters of two colors, that is, blue and violet, when they are blended, in the total content of the coloring matters contained in the blended navy ink, are normally 0.3 to 15% and 0.2 to 15%, respectively, are preferably 1 to 10% and 1 to 10%, respectively and are more preferably 2.5 to 7.5% and 2.5 to 7.5%, respectively. The contents of the coloring matters of three colors, that is, blue, violet and black, when they are blended are normally 0.2 to 10%, 0.2 to 10% and 0.1 to 10%, respectively, are preferably 1 to 7.5%, 0.5 to 7.5% and 0.5 to 7.5%, respectively and are more preferably 1.5 to 5%, 1.5 to 5% and 1.5 to 5%, respectively.

[0072] When the blue ink and the cyan ink and/or the navy ink are used together, the coloring matters contained in the blue ink and the cyan ink and/or the navy ink are preferably different from each other. When at least one of these inks contains two or more types of coloring matters, at least one of the two or more types of coloring matters is preferably different from the coloring matter contained in the other.

[0073] The coloring matters described above can be used in any of a powdered state, a massive state, a wet cake state and like. Coloring matters commercially available have various types of qualities such as "industrial dyeing powder" and "for inkjet printing," the manufacturing methods, the purities and the like thereof are different from each other. Coloring matters in a liquid state are also available. Among them, there are products that contain about 10 to 40 mass % of an inorganic salt such as sodium chloride or sodium sulfate in the total mass.

[0074] As the ink for inkjet printing, in order to achieve satisfactory ink storage stability, satisfactory discharge accuracy from an inkjet printer and the like, it is preferable to use a coloring matter and the like having as little impurity as possible. Since water or the like, for which a refining operation is not particularly operated, includes metal ions such as calcium ions and magnesium ions, when the unrefined water or the like described above is used for an ink, a very small number of ions described above are mixed into the ink.

[0075] In the present specification, for convenience, the inorganic salts and the metal ions and the like described above are referred to as "inorganic impurities" in the following description.

[0076] These inorganic impurities may cause the solubility of the coloring matter in the ink and the storage stability of the ink itself to be significantly degraded and may also cause the corrosion and wear of an inkjet printer head. Hence, the inorganic impurities are preferably removed from the ink. Examples of a method of removing these inorganic impurities include known methods such as an ultrafiltration method, a reverse osmosis method and an ion exchange method.

[0077] The upper limit of the content of the inorganic impurities that may be contained in the total mass of the ink is normally 1% or less, is preferably 0.5% or less and is more preferably 0.1% or less. The lower limit is 0%, that is, is preferably the detection limit of a detector or less.

[0078] The salt of the coloring matter represented by formula (1) described above means a salt that is formed with an inorganic or organic positive ion.

[0079] Among them, specific examples of the inorganic positive ion salt include an alkali metal salt, an alkaline earth metal salt and an ammonium salt. Among them, examples of the preferable inorganic positive ion salt include lithium, sodium and potassium salts and an ammonium (NH⁴⁺) salt.

[0080] As the organic positive ion salt, for example, the salt of quaternary ammonium ions represented by formula (3) below is present but there is no restriction on the salt.

[0081] Examples of the organic positive ion salt may include a free acid and a mixture of various types of salts thereof and a free acid of the tautomer, when the coloring matter has a tautomer, and a mixture containing various types of salts thereof. For example, any combinations such as a mixture of a sodium salt and an ammonium salt, a mixture of a free acid and a sodium salt and a mixture of a lithium salt, a sodium and an ammonium salt may be possible.

[0082] Depending on the type of salt, the physical values of the coloring matter such as the solubility may be different. Hence, preferably, the type of salt is appropriately selected as necessary, and when a plurality of salts and the like are included, the ratio thereof is changed, for example. Known methods can be used as the methods of salt formation, salt exchange and the like

[0083] In formula (3) described above, Z¹, Z², Z³ and Z⁴ each independently represent a group selected from a group consisting of a hydrogen atom, an alkyl group, a hydroxyalkyl group and hydroxyalkoxyalkyl group, and all Z¹ to Z⁴ are prevented from being hydrogen atoms.

[0084] Specific examples of the alkyl group of Z¹, Z², Z³ and Z⁴ in formula (3) described above include straight-chain and branched C1-C4 alkyl groups such as methyl, ethyl, n- propyl, isopropyl, n-butyl, isobutyl, sec-butyl and t- butyl.

[0085] Specific examples of the hydroxyalkyl group include hydroxy C1-C4 alkyl groups such as hydroxymethyl, hydroxyethyl, 3-hydroxypropyl, 2-hydroxypropyl, 4-hydroxybutyl, 3-hydroxybutyl and 2-hydroxybutyl.

[0086] Specific examples of the hydroxyalkoxyalkyl group include hydroxy C1-C4 alkoxy C1-C4 alkyl groups such as hydroxyethoxymethyl, 2-hydroxyethoxy ethyl, 3-hydroxy-ethoxy-propyl, 2-hydroxyethoxy propyl, 4-hydroxy-ethoxy-butyl, 3-hydroxy-ethoxy-butyl and 2-hydroxyethoxy butyl. Among them, the hydroxy C1-C4 alkoxy C1-C4 alkyl group (preferably, the hydroxyethoxy C1-C4 alkyl group) is preferable.

[0087] Examples of the particularly preferable ones among them include: a hydrogen atom; metyl; hydroxy C1-C4 alkyl groups such as hydroxymethyl, hydroxyethyl, 3-hydroxypropyl, 2-hydroxypropyl, 4-hydroxybutyl, 3-hydroxybutyl and 2-hydroxybutyl; and hydroxyethoxy C1-C4 alkyl groups such as hydroxyethoxymethyl, 2-hydroxyethoxy ethyl, 3-hydroxy-ethoxy-propyl, 2-hydroxyethoxy propyl, 4-hydroxy-ethoxy-butyl, 3-hydroxy-ethoxy-butyl and 2-hydroxyethoxy butyl.

[0088] Specific examples of the combination of Z¹, Z², Z³ and Z⁴ preferable in formula (3) described above are shown in table 2 below.

[Table 2]

Compound No.	Z1	Z2	Z3	Z4
1-1	H	CH3	CH3	CH3
1-2	CH3	CH3	CH3	CH3
1-3	H	-C2H4OH	-C2H4OH	-C2H4OH
1-4	CH3	-C2H4OH	C2H4OH	-C2H4OH
1-5	H	-CH2CH(OH)CH3	-CH2CH(OH)CH3	-CH2CH(OH)CH3
1-6	CH3	-CH2CH(OH)CH3	-CH2CH(OH)CH3	-CH2CH(OH)CH3
1-7	H	-C2H4OH	H	-C2H4OH
1-8	CH3	-C2H4OH	H	-C2H4OH
1-9	H	-CH2CH(OH)CH3	H	-CH2CH(OH)CH3
1-10	CH3	-CH2CH(OH)CH3	H	-CH2CH(OH)CH3
1-11	CH3	-C2H4OH	CH3	-C2H4OH
1-12	CH3	-CH2CH(OH)CH3	CH3	-CH2CH(OH)CH3

[0089] Examples of a water-soluble organic solvent contained in the magenta ink and the blue ink described above include polyhydric alcohols and pyrrolidones. The content of the water-soluble organic solvent in the total mass of the ink is normally 1 to 50% and is preferably 5 to 40%.

[0090] Examples of the polyhydric alcohol include: C2-C6 alcohols having 2 or 3 hydroxy groups such as glycerin, 1,3-pentanediol and 1,5-pentanediol; poly glyceryl ethers such as diglycerin and polyglycerin; polyoxy C2-C3 alkylene polyglyceryl ethers such as polyoxyethylene polyglyceryl ether and polyoxypropylene polyglyceryl ether; mono-, di-, and tri-C2-C3 alkylene glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol and polyethylene glycol; poly C2-C3 alkylene glycols (preferably, liquids) that have four or more repeating units and whose molecular weight is about 20000 or less, such as polyethylene glycol and polypropylene glycol; and 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.

[0091] Examples of the pyrrolidone include 2-pyrrolidone and N- methyl-2-pyrrolidone.

[0092] Among them, glycerin, diethylene glycol, propylene glycol, butyl carbitol and 2-pyrrolidone are preferable.

[0093] The water-soluble organic solvents may be used singly or together.

[0094] The magenta ink and the blue ink may further contain, as necessary, as a component other than the coloring matter, water and the water-soluble organic solvent, for example ink preparation agents such as a surfactant, a pH adjusting agent and an antiseptic and antifungal agent. The total of the ink preparation agents in the total mass of the ink is normally 0 to 10% and is preferably about 0.05 to 5%.

[0095] Examples of the surfactant include anionic, cationic, amphoteric and nonionic surfactants. Among them, the cationic surfactant is preferable.

[0096] Example of the anionic surfactant include alkylsulfocarboxylate, α- olefin sulfonate, polyoxyethylene alkyl ether acetate, N-acylamino acid and salts thereof, N-acylmethyltaurine salt, alkyl sulfate polyoxyethylene alkyl ether sulfate, alkyl sulfate polyoxyethylene alkyl ether phosphate, rosin acid soap, castor oil sulfate, lauryl alcohol sulfate, alkylphenol type phosphate ester, alkyl type phosphate ester, alkylaryl sulfonate, diethyl sulfosuccinate, diethylhexyl sulfosuccinate salt and dioctyl sulfosuccinate.

[0097] Examples of the cationic surfactant include a 2-vinyl pyridine derivative and a poly-4-vinyl pyridine derivative.

[0098] Examples of the amphoteric surfactant include a lauryldimethylaminoacetic acid betaine, 2-alkyl-N- carboxymethyl-N-hydroxyethylimidazolinium betaine, coconut oil fatty acid amide propyl dimethylamino acetic acid betaine, polyoctylpolyaminoethylglycine and an imidazoline derivative.

[0099] Examples of the nonionic surfactant include: ethers such as polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether and polyoxyethylene alkyl ether; esters such as polyoxyethylene oleic acid ester, polyoxyethylene distearate ester, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate and polyoxyethylene stearate; and acetylene alcohols 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-hexyn-3-ol. Other specific examples include products, made by Nissin Chemical Industry Co., Ltd., Surfynol 104, 105PG50, 82, 420, 440, 465, 485 and Olfine STG.

[0100] Among them, Surfynol is preferable, and Surfynol 104PG50 and Surfynol 440 are more preferable.

[0101] As the pH adjusting agent, an arbitrary substance can be used as long as it can perform control such that the pH of the ink falls within a range of 6.0 to 11.0. Examples thereof include: alkanolamines such as diethanolamine, dimethyl ethanolamine, diethyl ethanolamine and triethanolamine; hydroxides of alkali metals such as lithium hydroxide, sodium hydroxide and potassium hydroxide; ammonium hydroxide (ammonia water); alkali metal carbonates such as lithium carbonate, sodium carbonate and potassium carbonate; and tris (hydroxymethyl) aminomethane.

[0102] Among them, triethanolamine is preferable. The content of the pH adjusting agent in the total mass of the ink is normally 0.01 to 2% and is preferably 0.05 to 1%.

[0103] Examples of the antiseptic and antifungal agent include sodium dehydroacetate, sodium benzoate, sodium pyridinethion-1-oxide, zinc pyridinethion-1-oxide, 1,2-benzisothiazolin-3-on and amine salts of 1-benzisothiazolin-3-on, and Proxel GXL made by Avecia Inc. Proxel GXL is preferable.

[0104] Each of the inks described above is prepared by mixing the coloring matter, water, the water-soluble organic solvent and, as necessary, the ink preparation agent described above. Each component may be independently selected for each ink and may be different. Components other than the coloring matter selected for each ink are preferably the same. However, preferably, the content of each component in each ink is individually adjusted according to, for example, the physical properties of the coloring matter contained.

[0105] The content of each component in the total mass of each ink is collectively described below.

[0106] Unless otherwise particularly stated, the total content of the coloring matter is normally 0.5 to 15%, is preferably 1 to 10% and is more preferably 1 to 7.5%. When the "light" ink is used, it is normally 0.025 to 5%, is preferably 0.05 to 2.5% and is more preferably 0.05 to 2%.

[0107] The content of the water-soluble organic solvent is normally 1 to 50% and is preferably 5 to 40%.

[0108] The total content of the ink preparation agent is normally 0 to 10% and is preferably 0.05 to 5%.

[0109] The remaining part other than these components is water.

[0110] Each of the inks described above can be obtained by mixing the above components into a solution. Preferably, as the ink for inkjet printing, an ink solution obtained by a membrane filter or the like is filtered, and is thereby used as the ink in which foreign substances are removed. The diameter of the holes of the membrane filter is normally 0.1 to 1 µm and is preferably 0.1 to 0.5 µm.

[0111] The viscosity of each of the inks described above at 25°C is preferably within such a range that the viscosity is 3 to 20 mPa·s when it is measured with an E-type viscometer and 20 to 40 mN / m when it is measured by a plate method. The viscosity of the ink is preferably adjusted to have an appropriate value within the above range with consideration given to the discharge amount in the printer, the response speed, the dropping characteristic of the ink droplets, the characteristics of the inkjet head and the like.

[0112] The inkjet printing method described above is an inkjet textile printing method in which the ink is an ink set of at least two colors, that is the magenta ink and the blue ink described above is used, and that includes the sequential execution of at least three steps, that is, steps A to C below.

[Step A]

[0113] A step of discharging, in response to a recording signal, the droplets of at least one type of the magenta ink and the blue ink described above and attaching them on the textile

[Step B]

[0114] A step of fixing the coloring matter in the droplets of ink attached on the textile in step A described above to the textile by heat

[Step C]

[0115] A step of washing the coloring matter that is left on the textile and that is not fixed.

[0116] In addition to the three steps, that is, steps A to C described above, a step of performing pretreatment such as for preventing the coloring matter from bleeding in the textile may be further included before step A described above, and a pretreatment step on the textile is preferably included.

[0117] As the textile used for the inkjet printing method described above, a textile selected from polyamide fiber and mixed fibers containing polyamide fiber is preferable. Examples of the polyamide fiber include natural fibers such as silk and wool, and a synthetic polyamide fiber such as nylon. Examples of the mixed fiber include a fiber which contains at least the polyamide fiber and which is mixed with another fiber.

[0118] Examples of the fiber described above including a structure body of the fiber, preferably include a fabric formed of the fiber described above.

[0119] Examples of step A described above include a method of fitting a container (also referred to as an ink tank, an ink cartridge or the like) filled with at least the magenta ink and the blue ink described above to a predetermined position of the inkjet printer, discharging the droplets of the ink in response to the recording signal and attaching the ink on the fiber. When a full-color printed item is obtained, as described above, in addition to the two colors (the magenta and blue inks) it is possible to appropriately use the ink set of the 5 colors described above or 6 to 16 colors as necessary. Preferably, at this time, the inks of the individual colors are put into respective containers, and the containers are fitted to the predetermined position of the inkjet printer to be used. As the inkjet printer, for example, there is an inkjet printer that utilizes a piezo system using mechanical vibrations; and an inkjet printer that utilizes a bubble jet (registered trademark) system using bubbles produced by heating. The printer of any system can use the inkjet printing method described above.

[0120] Examples of step B described above include a method of leaving the fiber on which the ink is attached at room temperature to 130°C for about 0.5 to 30 minutes to perform preliminary drying, thereafter performing steaming processing and fixing the coloring matter to the fiber under heat and humidity conditions.

[0121] In the steaming processing, the textile is preferably left in an environment in which the humidity is 80 to 100% and the temperature is 95 to 105°C for 5 to 20 minutes.

[0122] In step C described above, the fiber to which the coloring matter has been fixed is preferably washed with water. The washing may be performed with water containing a surfactant.

[0123] After step C described above is performed, the washed fiber is dried normally at a temperature of 50 to 120°C for 5 to 30 minutes, and thus the dried printed item can be obtained.

[0124] Examples of the pretreatment step on the fiber performed before step A described above include a step of using, as a treatment liquid for the fiber, an aqueous solution containing at least both of one or more types of glue material and the pH adjusting agent for the pretreatment and previously providing it to the fiber before step A is performed. Preferably, in the treatment liquid for the fiber, a hydrotropic agent is further contained. The glue agent contained in the treatment liquid for the fiber, the pH adjusting agent for the pretreatment, the hydrotropic agent and the like may also be referred to as "pretreatment agents" or the like.

[0125] Examples of the method of providing the treatment liquid for the fiber to the fiber include a padding method. A drawing rate for the padding is preferably about 40 to 90% and is more preferably about 60 to 80%.

[0126] Examples of the glue agent contained in the treatment liquid for the fiber include: natural gums such as guar and locust bean; starches; seaweed such as sodium alginate and funori; plant skin such as pectinic acid; cellulose derivatives such as methyl cellulose, ethyl cellulose, hydroxyethyl cellulose and carboxymethyl cellulose; processed starch powder such as carboxymethyl starch; processed natural gums such as shiratsu gums and roasted bean gums; and synthetic glues such as polyvinyl alcohol and polyacrylic acid ester. Among them, natural gums such as guar and locust bean; and processed natural gums such as shiratsu gums and roasted bean gums are preferable.

[0127] As the pH adjusting agent for the pretreatment contained in the treatment liquid for the fiber, an agent that indicates acidity when it is formed into an aqueous solution is preferable. Specific examples thereof include acidic ammonium salts such as ammonium sulfate, ammonium tartrate and ammonium acetate. Among them, ammonium sulfate is preferable.

[0128] Examples of the hydrotropic agent contained in the treatment liquid for the fiber include urea and thiourea such as urea, dimethyl urea, thiourea, monomethyl thiourea and dimethyl thiourea. Among them, urea is preferable.

[0129] One type of pretreatment agents described above may be used singly or two or more types may be used together; the latter is more preferable.

[0130] For example, when a mixed fiber is used, it is difficult to unconditionally determine by the mixing ratio of the mixed fiber and the like the content of the pretreatment agents contained in the treatment liquid for the fiber. Roughly, in the total mass of the treatment liquid for the fiber, based on mass, the content of the glue agent is 0.5 to 5%, the content of the pH adjusting agent for the pretreatment is 0.5 to 5% and the remaining part is water. When the hydrotropic agent is further contained, likewise, the content thereof is 1 to 20%, and the remaining part is water.

[0131] The treatment liquid for the fiber is preferably acidic. The range of the pH is normally 7 or less and is preferably 5 to 7.

[0132] The fiber printed by the ink set of the present invention is excellent in various types of performance such as light resistance, water robustness and other robustness tests such as washing robustness, printing density, saturation, color tone and the size of the color reproduction range.

[0133] The ink set of the present invention can also achieve discharge performance without depending on a frequency value in a printer incorporating an industrial inkjet head in which a high viscosity ink is required.

[0134] Furthermore, discharge performance when the printer is left a predetermined time after inkjet printing and discharge (printing) when started again is also satisfactory.

[0135] Hence, the ink set of the present invention and the printing method using it are extremely suitable for the printing application of the fiber.

EXAMPLES

[0136] Although the present invention will be described in further detail below using examples, the present invention is not limited in any way by these examples.

[0137] For the temperature of a liquid, its internal temperature was measured, and unless otherwise particularly stated, all operations such as reactions and salting-out were performed under agitation.

[Synthesis Example]

[0138] According to the method described in Patent document 1, the coloring matter represented by formula (2) above was synthesized as follows.

[0139] 48.3 parts of the "monoazo compound (5)" disclosed in Patent Document 1 was added to 600 parts of water, and a 30% sodium hydroxide solution was added such that the pH thereof was adjusted to be 8.

[0140] A solution in which 20.3 parts of cyanuric chloride was dissolved in 100 parts of ethyl acetate was added, while a pH of 7 to 8 and a temperature of 15 to 20°C were maintained. After 30 minutes, a solution in which 17.8 parts of 2-aminoethane-sulfonic acid sodium salt was dissolved in 120 parts of water was add, while a pH of 7 to 7.5 and a temperature of 30°C were maintained, to the reaction mixture. After 30 minutes, the reaction mixture was heated to 50°C and was agitated at this temperature for one hour, and then the product was filtered. 200 parts of the obtained wet mixture was added to a solution of 200 parts of 1-methyl-2-pyrrolidinone and 25 parts of a diethanolamine. This reaction mixture was heated at 90°C for 3 hours, and was cooled to a room temperature. A solution in which 12 parts of sodium acetate was dissolved in 400 parts of ethanol was added to the reaction mixture. Its solid was separated by filtration, was washed with 300 parts of ethanol and was vacuum-dried at 60°C, the coloring matter represented by formula (2) above was obtained.

[0141] The maximum absorption wavelength (λmax) of the obtained coloring matter in water was 518 nm.

[0142] The contents of inorganic impurities in the total mass of the obtained coloring matter were measured by ion chromatography, and it was found that each of the contents of chlorine ions and sulfate ions was 10 ppm or less.

[0143] Mass spectrometry and ¹H- and ¹³C-NMR measurement were performed on the obtained coloring matter, and thus its structure was checked. Consequently, it was found to be the coloring matter represented by formula (2) above.

[Preparation of an ink set for inkjet printing]

[0144] Components shown in table 3 below were mixed and were agitated for about 1 hour, and thus an ink solution was obtained. The obtained ink solution was filtered with a membrane filter of 0.45 µm (product name: Cellulose acetate-based filter paper made by Advantech Co., Ltd.), and thus an inkjet printing ink for tests was prepared. The "water" used for the preparation of the ink solution was ion-exchanged water, and adjustments were made as follows: a 10% sodium hydroxide solution was added such that the pH of the ink solution was 8 to 9 and water was added such that the total amount was 100 parts.

[0145] As the "coloring matters" in table 3, coloring matters shown in table 4 below were used, and the inkjet printing inks for tests of two types of magenta and blue, for example 1, example 2, comparative example 1 and comparative example 2, were prepared and used as ink sets. The number of parts of each of the coloring matters used were also shown in table 4.

[Table 3]

Ink composition	Number of parts
Coloring matter	Shown in Table 4
Glycerin	5
Urea	5
2-pyrrolidone	20
Ethylene glycol	10
Butylcarbitol	5
Surfynol 440	0.1
Triethanolamine	0.1
Proxel GXL (S)	0.1
Sodium hydroxide + water	Remaining parts
Total	100

[Table 4]

Ink set	Ink	Coloring matter	Number of parts
Example 1	Magenta	Coloring matter of synthesis example	4
	Blue	C.I.Acid Blue 112	4
Example 2	Magenta	Coloring matter of synthesis example	4
	Blue	C.I.Acid Blue 140	4
Comparative Example 1	Magenta	C.I.Acid Red 131	4
	Blue	C.I.Acid Blue 249	4
Comparative Example 2	Magenta	C.I.Acid Red 249	4
	Blue	C.I.Direct Blue 87	4

[Preparation of test dyed cloth]

[0146] A textile treatment liquid containing two parts of guar, 2 parts of ammonium sulfate, 5 parts of urea and 91 parts of water was prepared, and a pretreatment step was performed by a pad method on nylon cloth (nylon taffeta). Specifically, the nylon cloth was immersed in the textile treatment liquid, and an extra amount of liquid was squeezed down with a rubber roller and thereafter it was dried at 60°C.

[0147] On the nylon cloth obtained as described above, with the ink set of example 1 or example 2, by an inkjet printer (product name: PIXUS ip4100 made by Canon Inc.), solid patterns of magenta to blue through violet were inkjet-printed in a gradation of 6 steps, that is, 100%, 85%, 70%, 55%, 40% and 25%, with the result that a printed item of the gradation was obtained. This printed item was preliminarily dried at a temperature of 60 to 80°C, and thereafter steaming processing was performed at a humidity of 90% or more at a temperature of 100 to 103°C for 20 minutes. The obtained printed item was washed with cold water for 5 minutes and was thereafter dried, with the result that pieces of test dyed cloth was obtained. These pieces of test dyed cloth were referred to as "dyed cloth 1" and "dyed cloth 2".

[0148] Pieces of comparison test dyed cloth were obtained in the same manner as in example 1 or example 2 except that, instead of the ink set of example 1 or example 2, the ink set of comparison example 1 or comparison example 2 was used. These pieces of comparison test dyed cloth were referred to as "comparison dyed cloth 1" and "comparison dyed cloth 2".

[Light resistance test]

[0149] A test was performed with the product Low temperature xenon weather meter XL75 made by Suga Test Instruments Co., Ltd., under conditions in which illumination was 100000 lux, humidity was 60% RH and temperature was 24°C. The test dyed cloth was left for 40 hours. The color of the test dyed cloth before and after the test was measured with a color measuring device, and the residual ratio of the coloring matter before and after the test was determined by the formula (reflection density after test / reflection density before test) x 100 (%).

[0150] As the color measuring device, SpectroEye made by GRETAG-MACBETH Inc. was used, and the color of the gradation part where the reflection density D value before the test was closest to 1.0 was measured.

[0151] The test results were evaluated on a scale of four steps A to D below.

A: Residual ratio is equal to or more than 95%

B: Residual ratio is equal to or more than 90% but less than 95%

C: Residual ratio is equal to or more than 85% but less than 90%

D: Residual ratio is less than 85%

[0152] The results are shown in table 5 below.

[Table 5]

Light resistance test results	Magenta part	Violet part	Blue part
Dyed cloth 1	A	A	A
Dyed cloth 2	A	A	A
Comparison dyed cloth 1	D	D	D
Comparison dyed cloth 2	D	D	D

[0153] As is clear from the results in table 5, it has been found that the residual ratio of the reflection density of the dyed cloth 1 and the dyed cloth 2 was higher than the comparison dyed cloth by 10% or more in the hue of each of magenta, violet and blue, and that they were extremely excellent in light resistance.

INDUSTRIAL APPLICABILITY

[0154] The inkjet printing ink set of the present invention can provide dyed cloth whose light resistance is satisfactory in the magenta-violet-blue hue in particular, and is extremely useful as an inkjet printing ink set.

Claims

1. An ink set for inkjet printing comprising inks of two colors of a magenta ink and a blue ink each of which comprises at least a coloring matter, water and a water-soluble organic solvent,
wherein the magenta ink comprises, as the coloring matter, at least a coloring matter represented by formula (1) below or a salt thereof,

in the formula (1), R¹ is a hydrogen atom or a C1-C6 alkyl group;
n is an integer of 2 to 4;
X is NR³R⁴, SR⁵ or OR⁶;
R³ and R⁴ are each independently a hydrogen atom; a C1-C6 alkyl group; a C2-C6 alkyl group that has, as a substituent, a hydroxy group, a methoxy group, a carboxy group or a sulfo group; an aralkyl group; or an aryl group that can have, as a substituent, a carboxy group or a sulfo group;
R³ and R⁴ may form a ring that has a heteroatom or no heteroatom;
R⁵ is a C2-C6 alkyl group that can have, as a substituent, a hydroxy group, a methoxy group, a carboxy group or a sulfo group;
R⁶ is a hydrogen atom or a C1-C6 alkyl group; and
R⁷ is a hydrogen atom; a C1-C6 alkyl group; a C2-C6 alkyl group that has, as a substituent, a cyano group, a carboxy group, a hydroxy group, a methoxycarbonyl group, an ethoxycarbonyl group or an acetyl group; or an aryl group that can have, as a substituent, a methyl group or a halogen atom.

2. The ink set for inkjet printing according to claim 1, wherein the blue ink comprises, as the coloring matter, an anthraquinone coloring matter.

3. The ink set for inkjet printing according to claim 2, wherein the anthraquinone coloring matter is a coloring matter that is selected from C. I. Acid Blue 23, 25, 27, 35, 40, 41, 43, 45, 47, 49, 52, 57, 58, 62, 62:1, 63, 64, 65, 68, 69, 74, 78, 78:1, 79, 80, 81, 81:1, 96, 111, 112, 124, 127, 127:1, 129, 129:1, 138, 138:1, 140, 145, 150, 175, 215, 230, 277, 277:1 and 344.

4. The ink set for inkjet printing according to any one of claims 1 to 3, wherein the blue ink comprises, as the coloring matter, at least C. I. Acid Blue 112 or C. I. Acid Blue 140.

5. The ink set for inkjet printing according to any one of claims 1 to 4, wherein in the coloring matter represented by the formula (1),
R¹ is a hydrogen atom;
n is an integer of 2 to 4;
X is NR³R⁴, OR⁶ or SR⁵;
R³ and R⁴ are each independently a hydrogen atom; a C1-C6 alkyl group; or a C2-C6 alkyl group that has, as a substituent, a hydroxy group or a sulfo group;
R⁵ is a C2-C6 alkyl group that can have, as a substituent, a hydroxy group, a carboxy group or a sulfo group;
R⁶ is a hydrogen atom or a C1-C6 alkyl group; and
R⁷ is a hydrogen atom; or a C2-C6 alkyl group that has, as a substituent, a cyano group.

6. The ink set for inkjet printing according to any one of claims 1 to 5, wherein a total content of the coloring matter in a total mass of each of the magenta ink and the blue ink is 0.5 to 20 mass %.

7. The ink set for inkjet printing according to any one of claims 1 to 6, wherein the total content of the coloring matter in the total mass of the magenta ink is 2 to 10 mass %, and the total content of the coloring matter in the total mass of the blue ink is 2 to 8 mass %.

8. The ink set for inkjet printing according to any one of claims 1 to 7, wherein all the coloring matters comprised in the blue ink are C. I. Acid Blue 112 or C. I. Acid Blue 140.

9. The ink set for inkjet printing according to any one of claims 1 to 8, wherein all the coloring matters comprised in the magenta ink are the coloring matter represented by the formula (1) or the salt thereof.

10. An inkjet printing method for a fiber that uses the ink set for inkjet printing according to any one of claims 1 to 9 and that sequentially performs at least three steps of steps A to C below:

step A: a step of discharging, in response to a recording signal, a droplet of each ink comprised in the ink set for inkjet printing and attaching the droplet on a fiber,

step B: a step of fixing the coloring matter in the droplet of each ink attached in step A on the fiber by heat and

step C: a step of washing the coloring matter that is left on the fiber and that is not fixed.

11. The inkjet printing method according to claim 10, wherein the fiber is selected from a polyamide fiber and a mixed fiber containing a polyamide fiber.

12. The fiber that is printed by the inkjet printing method according to claim 10 or 11.

13. The ink set for inkjet printing according to any one of claims 1 to 9, wherein the ink set is used to print a fiber that is selected from a polyamide fiber and a mixed fiber containing a polyamide fiber.