JP2020007508A - Ink and inkjet recording method - Google Patents

Abstract

To provide: an ink that realizes a large dot diameter when attached to recording media, particularly media not absorbing an ink; and an inkjet recording method using the ink.SOLUTION: The ink contains water, a water-insoluble colorant, a dispersant neutralized by ammonia, a compound represented by the formula (1) in the figure, and a glycol ether. The boiling point of the glycol ether is 50-270°C, each molecule has no or one hydroxy group, and more than 5 milliliters of pure water can be dissolved in 50 milliliters of the glycol ether.SELECTED DRAWING: None

Description

  The present invention relates to an aqueous ink, an ink jet recording method using the ink, and a recording medium to which the ink is attached.

  Among various color recording methods, an ink jet recording method using an ink jet printer is one of typical methods. In this method, recording is performed by generating small ink droplets and attaching them to a recording medium such as paper. In recent years, demand for industrial ink jet recording has increased, and an ink jet recording method capable of recording on various recording media has been demanded.

Among recording media, go to recording media that does not absorb ink such as vinyl chloride sheet, polypropylene film, polyethylene terephthalate film, polyethylene film, polyester film, nylon film, cellophane, metal, and glass (hereinafter, also referred to as “non-absorbing media”). Solvent inks, curable inks, etc., each containing substantially no water, have been proposed as inks used for recording. However, these inks have been problematic in terms of environmental and biological safety, such as VOC and skin sensitization. For this reason, there has been a strong demand for the development of an aqueous ink capable of recording on non-absorbing media, particularly an inkjet ink.
On the other hand, even when ink-jet recording is performed on a non-absorbing medium with an aqueous ink, the ink does not penetrate into the medium. For this reason, since the ink does not penetrate into the recording medium and spread, the dot diameter of each ink becomes smaller than that of the ink absorbing medium. When the dot diameter of the ink is small, for example, in the formation of a solid image, an economical loss such as an increase in the amount of required ink and a long printing time occurs. Further, when the amount of ink per unit area increases, unevenness in image quality of solid images, poor drying, and the like are likely to occur, which leads to deterioration of image quality. For this reason, there is a strong demand for an ink capable of obtaining a large dot diameter even when printing on a non-absorbing medium.

  Patent Literatures 1 and 2 disclose water-based inks that are also printed on non-ink-absorbing recording media.

International Publication No. 2008/102722 Gazette JP 2009-197126 A

  An object of the present invention is to provide an ink capable of obtaining a large dot diameter when attached to a recording medium, particularly a non-absorbing medium, and an ink jet recording method using the ink.

The present inventors have conducted intensive studies to solve the above-described problems, and as a result, have found that the inks described in 1) to 8) below can solve the above-mentioned problems, and have completed the present invention. .
1)
An ink containing water, a water-insoluble colorant, a dispersant neutralized with ammonia, a compound represented by the following formula (1), and glycol ether,
An ink in which the glycol ether satisfies the following (I) to (III).
(I) The boiling point is 50 to 270 ° C.
(II) The number of hydroxy groups in one molecule is 0 or 1.
(III) The amount of pure water dissolved in 50 ml of glycol ether is more than 5 ml.

(In the formula (1), R ¹ represents a hydroxy group, an alkoxy group having a hydroxy group, an acyloxy group, or an arylcarbonyloxy group, R ² represents a hydrogen atom or an alkyl group, and R ³ represents a hydrogen atom or an alkyl group. R ⁴ represents a hydrogen atom, a hydroxy group, or an alkyl group, and R ⁵ represents an alkyl group.)
2)
The ink according to the above 1), wherein the glycol ether has a boiling point of 75 to 260 ° C.
3)
The ink according to the above 1), wherein the glycol ether has a boiling point of 100 to 250 ° C.
4)
The ink according to the above 1), wherein the content of the compound represented by the formula (1) with respect to the total mass of the ink is 0.1% to 5% by mass.
5)
The ink according to any one of the above 1) to 4), further comprising a surfactant.
6)
Use of the ink according to any one of the above 1) to 5) in inkjet recording.
7)
An ink-jet recording method for performing recording by discharging ink droplets according to any one of the above 1) to 5) from an ink-jet printer and attaching the ink droplets to a recording medium.
8)
The inkjet recording method according to the above item 7), wherein the recording medium is a medium selected from an ink non-absorbing medium and an ink hardly absorbing medium.

  According to the present invention, an ink capable of obtaining a large dot diameter when attached to a recording medium, particularly a non-absorbing medium, and an ink jet recording method using the ink can be provided.

  In the present specification, “CI” means “color index”. Further, in the present specification, “%” and “parts” including examples and the like are all described on a mass basis unless otherwise specified.

[water]
The ink is an aqueous ink containing water. There is no limitation on the water that can be used, but water with little impurities such as inorganic ions is preferable. Examples of such water include ion-exchanged water and distilled water.

[Water-insoluble colorant]
Examples of the water-insoluble colorant include pigments, disperse dyes, solvent dyes, vat dyes, and the like. Of these, pigments, disperse dyes, and solvent dyes are preferred, and pigments are more preferred.
In the present specification, the water-insoluble colorant means a colorant having a solubility in 1 liter of water at 25 ° C. of usually 5 g or less, preferably 3 g or less, more preferably 1 g or less, and still more preferably 0.5 g or less.
Unless otherwise specified, the “water-insoluble colorant” may be hereinafter referred to as a “colorant”.
The type of the colorant contained in the ink is usually three or more types, preferably 3 to 5 types for black ink, and usually 3 types, preferably 2 types or 1 type for color inks other than black ink. . However, when the black ink contains carbon black as a colorant, the type of the colorant is preferably two or one. In the present specification, the color ink means a colored ink other than the black ink (for example, ink of each color such as yellow, magenta, cyan, red, orange, brown, violet, blue, green, and white).

Examples of the pigment include an inorganic pigment, an organic pigment, and an extender.
Examples of the inorganic pigment include carbon black, metal oxide, hydroxide, sulfide, ferrocyanide, and metal chloride.

Examples of the carbon black include carbon blacks such as thermal black, acetylene black, oil furnace black, gas furnace black, lamp black, gas black, and channel black.
Carbon black is, for example, Raven series manufactured by Columbia Carbon Co .; Monarch series, Regal series, and Mogul series manufactured by Cabot Corporation; ColorBlack series, Printex series, SpecialBlack series, and Nerox series manufactured by Orion Engineered Carbons; MA series, MCF series, No. 25, no. 33, no. 40, no. 47, no. 52, no. 900 and No. 2300 or the like.

  Examples of the metal oxide include C.I. I. Pigment White 6, 27; and aluminum hydroxide.

  Examples of the organic pigment include various pigments such as azo, diazo, phthalocyanine, quinacridone, isoindolinone, dioxazine, perylene, perinone, thioindigo, anthraquinone, and quinophthalone.

  Specific examples of the organic pigment include C.I. I. Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 24, 55, 73, 74, 75, 83, 93, 94, 95, 97, 98, 108, 114, 128, 129, 138, Yellow, such as 139, 150, 151, 154, 155, 180, 185, 193, 199, 202, 213; I. Pigment Red 5, 7, 12, 48, 48: 1, 57, 88, 112, 122, 123, 146, 149, 150, 166, 168, 177, 178, 179, 184, 185, 202, 206, 207, Red, such as 254, 255, 257, 260, 264, 272; I. Blue such as CI Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 22, 25, 60, 66, 80, etc .; I. Violet such as C.I. Pigment Violet 19, 23, 29, 37, 38, 50; I. Oranges such as CI Pigment Orange 13, 16, 68, 69, 71, 73; I. Pigment Green 7, 36, 54, etc .; I. Pigment Black 1 and other color pigments.

  Examples of the extender include silica, calcium carbonate, talc, clay, barium sulfate, and white carbon.

Examples of the disperse dye include known disperse dyes. Among them, C.I. I. Dyes selected from Disperss are preferred. Specific examples thereof include, for example, C.I. I. Disperss Yellow 9, 23, 33, 42, 49, 54, 58, 60, 64, 66, 71, 76, 79, 83, 86, 90, 93, 99, 114, 116, 119, 122, 126, 149, Yellow, such as 160, 163, 165, 180, 183, 186, 198, 200, 211, 224, 226, 227, 231, 237; I. Red such as Disperses Red 60, 73, 88, 91, 92, 111, 127, 131, 143, 145, 146, 152, 153, 154, 167, 179, 191, 192, 206, 221, 258, 283, etc .; C . I. Oranges such as Disperses Orange 9, 25, 29, 30, 31, 32, 37, 38, 42, 44, 45, 53, 54, 55, 56, 61, 71, 73, 76, 80, 96, 97; C; . I. Violet such as Dispers Violet 25, 27, 28, 54, 57, 60, 73, 77, 79, 79: 1; I. Dispers Blue 27, 56, 60, 79: 1, 87, 143, 165, 165: 1, 165: 2, 181, 185, 197, 202, 225, 257, 266, 267, 281, 341, 353, 354, And disperse dyes of each color such as blue such as 358, 364, 365, and 368.
Examples of the solvent dye include C.I. I. Dyes selected from Solvent are preferred.

The content of the colorant with respect to the total mass of the ink is usually 1 to 30%, preferably 1 to 10%, more preferably 2 to 7%.
The average particle size of the colorant is usually 50 nm to 300 nm, preferably 60 nm to 250 nm. In the present specification, the average particle size refers to an average particle size of particles measured using a laser light scattering method.

[Dispersant neutralized with ammonia]
The ammonia is not particularly limited, and a gas, a liquid dissolved in water or an organic solvent, or the like can be used. Among them, aqueous ammonia is preferable.
"Dispersant neutralized with ammonia" means a dispersant adjusted to the following degree of neutralization with ammonia. The degree of neutralization of the dispersant is generally 30 to 200%, preferably 50 to 150%, more preferably 75 to 125%, assuming that the degree of neutralization with the theoretical equivalent of the acid value of the dispersant is 100%. , More preferably 90% to 110%.

The dispersant is not particularly limited, and a known dispersant can be used. As the dispersant, a dispersant having a functional group which is acidic in a free form, such as a carboxy group, a sulfo group, and a phosphonic acid group, is preferable. Among them, monomers selected from styrene, (meth) acrylate, and (meth) acrylic acid (preferably two or more monomers, more preferably two to six monomers, and more preferably two to four monomers Polymers composed of monomers, more preferably two to three types of monomers) are preferred. In this specification, (meth) acrylate includes both acrylate and methacrylate, and the same applies to (meth) acrylic acid and the like.
As the (meth) acrylate, a monomer selected from an alkyl (meth) acrylate and an arylalkyl (meth) acrylate is preferable, and a monomer selected from an alkyl methacrylate and an arylalkyl methacrylate is preferable.
As the alkyl (meth) acrylate, C1-C4 alkyl (meth) acrylate is preferable, C1-C4 alkyl methacrylate is more preferable, alkyl (meth) acrylate selected from methyl methacrylate and butyl methacrylate is further preferable, and n-butyl methacrylate is preferable. Particularly preferred.
As the arylalkyl (meth) acrylate, C6-C10 aryl C1-C4 alkyl (meth) acrylate is preferable, C6-C10 aryl C1-C4 alkyl methacrylate is more preferable, phenyl C1-C4 alkyl methacrylate is more preferable, and benzyl methacrylate is particularly preferable. preferable.
Examples of the polymer include a polymer composed of a monomer selected from at least one of alkyl (meth) acrylate, arylalkyl (meth) acrylate, and (meth) acrylic acid; and a styrene- (meth) acryl-based polymer. Polymers selected from polymers are preferred.

Examples of the polymer composed of a monomer selected from at least one of alkyl (meth) acrylate, arylalkyl (meth) acrylate, and (meth) acrylic acid include A composed of two blocks, A block and B block. -B block polymers are preferred.
The A block is preferably composed of an arylalkyl (meth) acrylate and can include (meth) acrylic acid. At this time, the content of the (meth) acrylic acid is usually 0 to 5 mol%, preferably 0 to 3 mol%, more preferably 0 to 1 mol%, and still more preferably 0 to 5 mol% with respect to the arylalkyl (meth) acrylate. ~ 0.1 mol%.
The B block is preferably a copolymer composed of alkyl (meth) acrylate and (meth) acrylic acid.
As the AB block polymer, a water-insoluble polymer is preferable. In the present specification, the water-insoluble polymer means that the solubility in 1 liter of water at 25 ° C. is usually 5 g or less, preferably 3 g or less, more preferably 1 g or less, and further preferably 0.5 g or less. The lower limit of solubility includes 0 g. As such an AB block polymer, for example, an AB block polymer obtained by a living radical polymerization method disclosed in WO 2013/115071 Gazette is exemplified.
Examples of the dispersant include the same as the AB block polymer disclosed in International Publication No. 2013/115071 Gazette, including the preferred ones, except that the neutralizing agent is an amine compound. The same applies to the method for producing the AB block polymer.

  As the styrene- (meth) acrylic polymer, Joncryl series manufactured by BASF is preferred.

The acid value of the dispersant is usually 90 to 200 mgKOH / g, preferably 100 to 150 mgKOH / g, more preferably 100 to 120 mgKOH / g.
The weight average molecular weight of the dispersant is usually 10,000 to 60,000, preferably 10,000 to 40,000, and more preferably 15,000 to 30,000.
The usage ratio of the dispersant to the total mass of the colorant is usually 0.1 to 1.0, preferably 0.1 to 0.6, and more preferably 0.2 to 0.5.

[Compound represented by Formula (1)]
In the above formula (1), examples of the alkoxy group having a hydroxy group in R ¹ include hydroxy C1-C6 alkoxy, preferably hydroxy C1-C4 alkoxy, and more preferably hydroxy C2-C4 alkoxy. Examples of the alkoxy moiety include straight-chain, branched-chain or cyclic alkoxy, preferably straight-chain or branched-chain, and more preferably straight-chain. Further, the substitution position of the hydroxy group is not particularly limited. Specific examples thereof include hydroxymethoxy, 2-hydroxyethoxy, 2-hydroxy-n-propoxy, 3-hydroxy-n-propoxy, 2-hydroxy-n-butoxy, 3-hydroxy-n-butoxy, and 4-hydroxy- n-butoxy, 2-hydroxy-n-pentoxy, 3-hydroxy-n-pentoxy, 4-hydroxy-n-pentoxy, 5-hydroxy-n-pentoxy, 2-hydroxy-n-hexyloxy, 3-hydroxy-n- Linear groups such as hexyloxy, 4-hydroxy-n-hexyloxy, 5-hydroxy-n-hexyloxy and 6-hydroxy-n-hexyloxy; 2-hydroxyisopropoxy, 2-hydroxyisobutoxy, 3-hydroxyisobutoxy, 2-hydroxyisopentoxy, 3-hydroxyisope Branched chains such as toxy, 4-hydroxyisopentoxy, 2-hydroxyisohexyloxy, 3-hydroxyisohexyloxy, 4-hydroxyisohexyloxy, and 5-hydroxyisohexyloxy; 2-hydroxycyclopropoxy, 2 Cyclic compounds such as -hydroxycyclobutoxy, 3-hydroxycyclobutoxy, 2-hydroxycyclopentoxy, 3-hydroxycyclopentoxy, 2-hydroxycyclohexyloxy, 3-hydroxycyclohexyloxy, and 4-hydroxycyclohexyloxy; No. Of these, 2-hydroxyethoxy is preferred.

Examples of the acyloxy group for R ¹ include straight-chain, branched-chain and cyclic ordinary C1-C6 acyloxy, preferably C1-C5 acyloxy, and more preferably C2-C5 acyloxy. Of these, straight-chain ones are preferred. Further, an acyloxy group having one more carbonyl group in addition to the ester carbonyl of the acyloxy moiety is preferable. Specific examples thereof include linear ones such as methylcarbonyloxy, ethylcarbonyloxy, n-propylcarbonyloxy, n-butylcarbonyloxy, and n-pentylcarbonyloxy; isopropylcarbonyloxy, isobutylcarbonyloxy, t-butylcarbonyl Branched chains such as oxy, isopentylcarbonyloxy, 1-ethylpropylcarbonyloxy, 1,1-dimethylpropylcarbonyloxy, and 2,2-dimethylpropylcarbonyloxy; cyclopentylcarbonyloxy, cyclobutylcarbonyloxy, cyclopentylcarbonyloxy Cyclic compounds such as 1-oxoethylcarbonyloxy, 2-oxopropylcarbonyloxy, 2-oxobutylcarbonyloxy, 3-oxobutylcarbonyloxy 2-oxo-pentyl carbonyloxy, 3- oxopentyloxy carbonyloxy, 4-oxo-pentylcarbonyl oxy such as those having one more carbonyl groups; and the like. Among these, 1-oxoethylcarbonyloxy and 3-oxobutylcarbonyloxy are preferred.

The arylcarbonyloxy group for R ¹ usually includes C6-C12 arylcarbonyloxy. Specific examples include phenylcarbonyloxy, naphthylcarbonyloxy, biphenylcarbonyloxy and the like, among which phenylcarbonyloxy is preferred.

Among them, R ¹ is preferably a hydroxy group or an alkoxy group having a hydroxy group, and more preferably a hydroxy group.

Examples of the alkyl group for R ^{2 to} R ⁵ include a C1-C6, preferably C1-C4, linear, branched or cyclic alkyl group. Specific examples thereof include linear ones such as methyl, ethyl, n-propyl, n-butyl, n-pentyl and n-hexyl; isopropyl, isobutyl, sec-butyl, t-butyl, isopentyl and t-pentyl. , Isohexyl, t-hexyl and the like; cyclic ones such as cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl; and the like.
R ² is preferably a straight or branched chain, and more preferably a branched chain. Among the above, n-propyl, isopropyl and t-butyl are preferred, and isopropyl is more preferred.
R ³ is preferably a straight chain, and among the above, methyl is preferred.
R ⁴ is preferably a straight or branched chain, and among the above, n-propyl, isopropyl and t-butyl are preferred.
R ⁵ is preferably a straight or branched chain, and more preferably a branched chain. Among the above, ethyl, n-propyl, isopropyl and t-butyl are preferred, and isopropyl is more preferred.

Of the above,
As R ₁ , a hydroxy group or an alkoxy group having a hydroxy group is preferred, and a hydroxy group is more preferred.
R ₂ is preferably an alkyl group, more preferably a branched alkyl group.
As R ₃ , an alkyl group is preferable, and a linear alkyl group is more preferable.
R ₄ is preferably a hydrogen atom or a hydroxy group.
R ₅ is preferably a branched alkyl group.

Specific examples of the compound represented by the formula (1) are shown in Table 1 below, but the present invention is not limited to these specific examples. The abbreviations in Table 1 have the following meanings.
Ph: phenyl.
i-Pr: isopropyl.
n-Pr: normal propyl.
t-Bu: tertiary butyl.
Et: ethyl.

  Among the compounds represented by the formula (1), commercially available products include Texanol manufactured by Eastman Chemical Company.

  Since the compound represented by the formula (1) is hardly soluble in water, the content of the formula (1) changes depending on the composition of the ink. For this reason, it is difficult to specify the content of the compound represented by the formula (1) based on the total mass of the ink. As a guide, it is usually about 0.5% to 5%, preferably about 0.6% to 3%, more preferably about 0.6% to 2%, and still more preferably about 0.8% to 1.2%.

[Glycol ether]
The glycol ether satisfies the following (I) to (III).
(I)
The boiling point is usually 50 to 270 ° C, preferably 75 to 260 ° C, more preferably 100 to 250 ° C.
(II)
The number of hydroxy groups in one molecule is 0 or 1.
(III)
The amount of pure water dissolved in 50 ml of glycol ether is usually greater than 5 ml. It is preferably at least 10 ml, more preferably at least 15 ml. There is no particular upper limit, and glycol ethers arbitrarily miscible with water can also be used. The amount of pure water dissolved can be measured as follows.
[Method for measuring the amount of pure water dissolved]
50 ml of glycol ether is placed in a 100 ml graduated cylinder equipped with a stopper, and allowed to stand in a constant temperature water bath at 20 ° C. for 30 minutes. After adding an appropriate amount of water to a measuring cylinder and mixing, the mixture is allowed to stand in a constant temperature water bath at 20 ° C. for 30 minutes. The state of the liquid after standing is visually observed, and if uniform, the test is continued by adding an appropriate amount of water. If the state of the liquid after standing still is non-uniform (usually slightly turbid white), the test is terminated, and the amount of water finally confirmed to be uniform is defined as the amount of pure water dissolved.
Before the above measurement, the amount of water dissolved in the glycol ether can be simply measured to reduce the labor of the measurement.
Further, in the present specification, when 50 ml of water is added to 50 ml of glycol ether and the water is uniform, it is determined that there is a possibility that the water is miscible with water. Did not.

  As the glycol ether, a compound represented by the following formula (2) or the following formula (3) is preferable.

In Formula (2), R ⁶ and R ⁷ each independently represent a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, or an aryl group, and both R ⁶ and R ⁷ are not simultaneously hydrogen atoms. . As R ⁶ and R ⁷ , a hydrogen atom, an alkyl group, and an alkenyl group are preferable.
x and y represent 0 to 3, and the sum of x and y is 1 to 3.
However, when both R ⁶ and R ⁷ are simultaneously a group other than a hydrogen atom, the sum of the carbon numbers of R ⁶ and R ⁷ is usually 2 to 7, preferably 2 to 6, more preferably 2 to 5, and further more preferably Is 2-4.
When both R ⁶ and R ⁷ are simultaneously a group other than a hydrogen atom, x is preferably 0 to 3, y is preferably 0 or 1, x is preferably 1 to 3, y is more preferably 0, x is 2, y is more preferably 0.

Examples of the alkyl group, alkenyl group, and alkynyl group for R ⁶ and R ⁷ include a linear, branched, or cyclic group. Among these, a linear or branched group is preferred. The range of the number of carbon atoms is usually C1-C5, preferably C1-C4. However, the range of the carbon number of the alkenyl group and the alkynyl group is usually C2-C5, preferably C2-C4.
Specific examples of the alkyl group include, for example, a linear alkyl group such as methyl, ethyl, propyl, butyl, and pentyl; a branched alkyl group such as isopropyl, isobutyl, sec-butyl, t-butyl, isopentyl, and t-pentyl; And cyclic alkyl groups such as cyclopropyl, cyclobutyl, and cyclopentyl.
Specific examples of the alkenyl group include, for example, linear alkenyl groups such as vinyl, 2-propenyl (allyl), 3-butenyl and 4-pentenyl; and 1-methyl-2-propenyl and 1-methyl-3-butenyl. A branched alkenyl group; and a cyclic alkenyl group such as cyclobutenyl and cyclopentenyl. Among these, a straight-chain alkenyl group is preferred.
Specific examples of the alkynyl group include, for example, a straight-chain alkynyl group such as acetylenyl, 2-propynyl and 3-butynyl; and a branched-chain alkynyl group such as 1-methyl-2-propynyl and 1-methyl-3-butynyl. .

The aryl group for R ⁶ and R ⁷ includes a C6-C10 aryl group. Among them, a phenyl group or a naphthyl group is preferred; a phenyl group is more preferred.

In the formula (3), R ⁸ and R ⁹ each independently represent a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, or an aryl group, and both R ⁶ and R ⁷ are not simultaneously hydrogen atoms. . As R ⁸ and R ⁹ , a hydrogen atom and an alkyl group are preferable.
As R ⁸ and R ⁹ , one is preferably a hydrogen atom, and the other is preferably a group other than a hydrogen atom.
Examples of the alkyl group, alkenyl group, alkynyl group, and aryl group for R ⁸ and R ⁹ include the same groups as those described for R ⁶ and R ⁷ , including the preferred groups.

R ¹⁰ includes straight-chain, branched-chain, or cyclic C2-C5 alkylene. Among these, straight-chain or branched-chain alkylene is preferred, and branched-chain alkylene is more preferred.
Specific examples thereof include linear alkylene such as ethylene, propylene, butylene and pentylene; branched alkylene such as methylethylene, methylpropylene, methylbutylene, dimethylethylene and dimethylpropylene; cyclopropylene, cyclobutylene and cyclopentylene And the like.

  The content of the glycol ether in the total mass of the ink is usually 3 to 50%, preferably 4 to 40%, more preferably 4 to 30%, still more preferably 4 to 25%, and particularly preferably 5 to 20%. It is.

The pH of the ink is usually 5 to 11, preferably 7 to 10 for the purpose of improving the storage stability of the ink and preventing corrosion of the ink jet printer members.
The surface tension of the ink is usually 10 to 50 mN / m, preferably 20 to 40 mN / m.
The viscosity of the ink is usually 30 mPa · s or less, preferably 20 mPa · s or less, and the lower limit is about 0.1 mPa · s.

  The ink may optionally contain an ink preparation as a component other than the above. Examples of the ink preparation include water-soluble organic solvents, preservatives, fungicides, pH adjusters, chelating agents, rust inhibitors, water-soluble ultraviolet absorbers, antioxidants, surfactants, and wax preparations. No. One type of ink preparation can be used, or two or more types can be used in combination.

Examples of the water-soluble organic solvent include C1-C6 alcohol (monool) such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol or tert-butanol; N, N-dimethylformamide or N, N- Carboxylic acid amides such as dimethylacetamide; lactams such as 2-pyrrolidone, N-methyl-2-pyrrolidone or N-methylpyrrolidin-2-one; 1,3-dimethylimidazolidin-2-one or 1,3-dimethylhexa Cyclic ureas such as hydropyrimid-2-one; ketones or keto alcohols such as acetone, 2-methyl-2-hydroxypentan-4-one and ethylene carbonate; cyclic ethers such as tetrahydrofuran and dioxane; ethylene glycol and diethylene glycol , Propi Glycol, 1,3-propanediol, 1,2-hexanediol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,3-propanediol, diethylene glycol, triethylene glycol, tetraethylene Glycol, dipropylene glycol, mono-, oligo- or polyalkylene glycol or thioglycol having C2-C6 alkylene units such as polyethylene glycol, polypropylene glycol, thiodiglycol or dithiodiglycol having a molecular weight of 400, 800, 1540 or more; glycerin , Diglycerin, trimethylolpropane, hexane-1,2,6-triol, and other polyols (triols); γ-butyrolactone, dimethylsulfoxide, and the like.
Further, glycol ethers other than the above-mentioned glycol ethers, for example, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-n-butyl ether, dipropylene glycol monoisopropyl ether and the like are also included.

Examples of preservatives include, for example, organic sulfur-based, organic nitrogen-sulfur-based, organic halogen-based, haloarylsulfone-based, iodopropargyl-based, haloalkylthio-based, nitrile-based, pyridine-based, 8-oxyquinoline-based, and benzothiazole-based , Isothiazoline, dithiol, pyridine oxide, nitropropane, organotin, phenol, quaternary ammonium salt, triazine, thiazine, anilide, adamantane, dithiocarbamate, brominated indanone, benzyl Bromoacetate-based or inorganic salt-based compounds are exemplified.
Proxel series such as Proxel GXL (S) and Proxel XL-2 (S) manufactured by Arch Chemical Company are preferable.

  Specific examples of the fungicide include sodium dehydroacetate, sodium benzoate, sodium pyridinethione-1-oxide, ethyl p-hydroxybenzoate, 1,2-benzisothiazolin-3-one and salts thereof. .

  Any substance capable of adjusting the pH to the above range can be used as the pH adjuster. Specific examples thereof include amines such as ammonia, trimethylamine, triethylamine, and triethanolamine; carbonates of alkali metals such as lithium carbonate, sodium carbonate, sodium hydrogencarbonate, and potassium carbonate; sodium silicate, potassium acetate, and the like. Alkali metal salts of organic acids; and alkali metal phosphates such as disodium phosphate.

  Specific examples of the chelating reagent include, for example, disodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, and sodium uracildiacetate.

  Specific examples of the rust inhibitor include, for example, acidic sulfite, sodium thiosulfate, ammonium thioglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite, and the like.

  Examples of the water-soluble ultraviolet absorber include, for example, sulfonated benzophenone-based compounds, benzotriazole-based compounds, salicylic acid-based compounds, cinnamic acid-based compounds, and triazine-based compounds.

  Examples of the antioxidant include, for example, various organic and metal complex-based antifading agents. Examples of the organic anti-fading agent include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indans, chromans, alkoxyanilines, and heterocycles. Can be

Examples of the surfactant include known surfactants such as, for example, anions, cations, nonionics, amphoteric, silicone-based, and fluorine-based surfactants. The type of surfactant is not particularly limited, and can be used as needed.
Examples of the anionic surfactant include alkyl sulfocarboxylates, α-olefin sulfonates, polyoxyethylene alkyl ether acetates, polyoxyethylene alkyl ether sulfates, N-acyl amino acids or salts thereof, and N-acylmethyl taurine salts. Alkyl sulfate polyoxyalkyl ether sulfate, alkyl sulfate polyoxyethylene alkyl ether phosphate, rosin acid soap, castor oil sulfate, lauryl alcohol sulfate, alkylphenol-type phosphate, alkyl-type phosphate, Examples thereof include alkylaryl sulfonates, diethyl sulfosuccinate, diethylhexyl sulfosuccinate, dioctyl sulfosuccinate, and ADEKACOL EC-8600 manufactured by ADEKA Corporation.

  Examples of the cationic surfactant include a 2-vinylpyridine derivative and a poly-4-vinylpyridine derivative.

  Nonionic surfactants 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; Ester systems such as oxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, polyoxyethylene stearate; , 4,7,9-Tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 3,5-dimethyl 1-hexyne-3-ol such as acetylene glycol (alcohol) -based, and C2-C4 alkyleneoxy adducts thereof; polyglycol ether and the like.

  Examples of the amphoteric surfactant include lauryl dimethylamino acetate betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, coconut oil fatty acid amide propyldimethylamino acetate betaine, polyoctyl polyaminoethyl glycine, and imidazoline derivatives. No.

  Examples of the silicone-based surfactant include polyether-modified siloxane and polyether-modified polydimethylsiloxane. Examples include Dynol 960 and 980 manufactured by Air Products; Sylface SAG001, SAG002, SAG003, SAG005, SAG503A, SAG008, SAG009 and SAG010 manufactured by Nissin Chemical Co., Ltd .; 348, 349, 3455, LPX 23298 and the like. Among these, a polyether-modified siloxane known by BYK series manufactured by BYK-Chemie is preferred.

  Examples of the fluorine-based surfactant include a perfluoroalkylsulfonic acid compound, a perfluoroalkylcarboxylic acid-based compound, a perfluoroalkylphosphate ester compound, a perfluoroalkylethylene oxide adduct, and a side chain having a perfluoroalkylether group. And the like. As the fluorine-based surfactant, various kinds of products can be easily purchased from, for example, DuPont, Omnova, DIC, and Big Chemie.

When the ink is prepared, a known method for producing a dispersed ink can be used. As an example, for example, a method of preparing an ink by preparing an aqueous dispersion from a colorant and a dispersant, adding glycol ether to the dispersion, and an ink preparation as needed, and mixing. Is mentioned.
Examples of a method of dispersing the colorant with a water-insoluble dispersant include a phase inversion emulsification method. That is, a dispersant is dissolved in an organic solvent such as 2-butanone, and an aqueous solution of a neutralizing agent is added to prepare an emulsion. A colorant is added to the obtained emulsion to carry out a dispersion treatment to obtain a liquid. By distilling off the organic solvent and a portion of the water under reduced pressure from the liquid thus obtained, a target colorant dispersion can be obtained.
Examples of the dispersion treatment include a method in which a colorant and a dispersant are placed in a sand mill (bead mill), a roll mill, a ball mill, a paint shaker, an ultrasonic disperser, a microfluidizer, or the like to perform dispersion. For example, when a sand mill is used, beads having a particle size of about 0.01 mm to 1 mm can be used, and the dispersion treatment can be performed by appropriately setting the filling rate of the beads.
Operations such as filtration and / or centrifugation can be performed on the dispersion obtained as described above. By this operation, the size of the particles contained in the dispersion can be made uniform.

When the ink is used as an inkjet ink, an ink having a low content of inorganic impurities such as metal cation chloride (eg, sodium chloride) and sulfate (eg, sodium sulfate) is preferable. Such inorganic impurities are often contained in commercially available coloring agents. The standard of the inorganic impurity content is about 1% by mass or less based on the total mass of the colorant, and the lower limit may be below the detection limit of the analytical instrument, that is, 0%. As a method for obtaining a coloring agent having a small amount of inorganic impurities, for example, a method using a reverse osmosis membrane; a solid of the coloring agent is suspended and stirred in a mixed solvent of C1-C4 alcohol such as methanol and water; And drying, and a method of exchanging and adsorbing inorganic impurities with an ion exchange resin. By such a method, the content of the inorganic impurities with respect to the total mass of the colorant is preferably set to 1% or less. The lower limit can be equal to or less than the detection limit of the detection device, that is, 0%.
When the ink is used as an inkjet ink, the ink is preferably subjected to precision filtration. When performing microfiltration, a membrane filter and / or glass filter paper or the like can be used. The pore size of a filter or the like when performing microfiltration is usually 0.5 μm to 20 μm, preferably 0.5 μm to 10 μm.

  The ink can be used in various recording and printing fields. For example, it is suitable for uses such as writing, printing, information recording, and textile printing. In particular, it is preferably used for ink jet recording.

The ink jet recording method is a method of performing recording by discharging droplets of the ink from an ink jet printer and attaching the ink droplets to a recording medium. There are no particular restrictions on the ink nozzles and the like of the ink jet printer that ejects the ink, and they can be appropriately selected according to the purpose.
As an ink jet recording method, a method for improving the image quality by ejecting a large number of inks having a low content of a colorant in a small volume to improve the image quality; a plurality of inks having substantially the same hue but different in the content of the colorant in the ink. A method of improving image quality using ink; and a method of improving fixability of a colorant to a recording medium by using a colorless and transparent ink and an ink containing a colorant in combination are also included. The ink can be used as a colorant-containing ink in these methods.

  As the inkjet recording method, a known method can be used. Examples thereof include a charge control method, a drop-on-demand method (also referred to as a pressure pulse method), an acoustic ink jet method, a thermal ink jet method, and the like.

The recording medium is not particularly limited as long as it is a substance colored by the ink. Examples thereof include recording media such as paper and fiber having an ink receiving layer, and recording media having poor ink absorption without an ink receiving layer (hereinafter, also referred to as “hard absorbing media”) and non-ink absorbing media. Absorbing media.
Here, when recording is performed on a hard-absorbing medium and a non-absorbing medium with a normal aqueous ink, it is difficult to absorb the ink, so that mottling or repelling of the ink occurs. On the other hand, the ink can perform recording on such a recording medium without repelling the ink. For this reason, the recording medium is preferably a hardly absorbable medium or a non-absorbable medium, and particularly preferably a non-absorbable medium. Examples of poorly absorbable media include plain paper, media used for gravure printing, offset printing, etc., art paper, coated paper, matte paper, cast paper, and the like. Examples of the non-absorbing medium include a vinyl chloride sheet, a sheet made of a polymer resin, glass, and rubber.
When performing recording on the hardly absorbable medium or the non-absorbable medium with the ink, the recording can be performed while heating each medium. The heating temperature of the medium is usually 30C to 70C, preferably 30C to 60C, and more preferably 35C to 50C.

When recording on a recording medium by the ink jet recording method, for example, a container (referred to as an ink tank or the like) containing the ink is loaded at a predetermined position of an ink jet printer, and recording is performed on the recording medium by the recording method.
The inkjet recording method can perform full-color recording as an ink set of a plurality of inks selected from the color inks. At that time, the containers containing the inks of the respective colors are loaded into the predetermined positions of the ink jet printer in the same manner as described above, and are recorded on the recording medium by the recording method described above.

All the components described above can be used alone or in combination of two or more, unless otherwise specified.
Regarding all the above-mentioned items, a combination of preferable ones is more preferable, and a combination of more preferable ones is still more preferable. The same applies to combinations of preferred and more preferred ones, combinations of more preferred and further preferred ones, and the like.

The ink of the present invention is a water-based ink substantially containing water, and is a recording medium having an ink receiving layer such as ink jet paper, a general-purpose plain paper having no ink receiving layer, a hardly absorbing medium, and a non-absorbing medium. In any case, a high-quality recorded image without repelling can be obtained.
Further, the dot diameter of the ink of the recorded image obtained with the ink of the present invention is larger than the dot diameter of the recorded image obtained with the normal ink. For this reason, solid printing can be efficiently performed even in one-pass printing without printing in a plurality of passes, and therefore, when the ink of the present invention is used, both the printing time and the ink consumption can be reduced. This effect is particularly useful in industrial applications. In addition, when solid printing is performed in a plurality of passes because of a small dot diameter, the amount of ink used increases, so that a recorded image may have mottling and / or graininess. However, the recorded image obtained by the ink of the present invention does not cause such a phenomenon.
Further, the recorded image obtained by the ink of the present invention is excellent in abrasion resistance, the roundness of the ink dot on the recording medium is high, the smoothness is obtained, and an image which does not impair the glossiness is obtained. Further, a recorded image excellent in various fastnesses such as water resistance, light resistance, heat resistance, and oxidation gas (eg, ozone gas resistance) can be obtained.

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to the following Examples. In the text, “parts” and “%” are based on mass unless otherwise specified. In addition, all operations such as each synthesis reaction and crystallization were performed with stirring unless otherwise specified.
When measurement of the pigment solid content was necessary, it was determined by the dry weight method using MS-70 manufactured by A & D Corporation. In addition, the pigment solid content in the examples is a converted value of only the pigment solid content from a measured value obtained by a dry weight method.

[(A) Preparation of Dispersion 1]
A block copolymer described in Synthesis Example 3 of WO 2013/115071 was prepared. 6.6 parts of the obtained copolymer was dissolved in 20 parts of 2-butanone to form a uniform solution. To this solution was added a solution prepared by dissolving 0.21 part of a 28% aqueous ammonia solution in 51 parts of ion-exchanged water, and the mixture was stirred for 1 hour to obtain an emulsion. C. was added to the obtained emulsion. I. Pigment Blue 15: 3 (Cyanine Blue A220J, manufactured by Dainichi Seika Kogyo Co., Ltd.) was added, and the mixture was dispersed in a sand grinder for 15 hours at 1500 rpm to obtain a liquid. 100 parts of ion-exchanged water was added dropwise to the obtained liquid, and the dispersion beads were removed by filtration. Then, 2-butanone and water were distilled off under reduced pressure with an evaporator to obtain a cyanide having a pigment solid content of 11.9%. A dispersion “Dp1” was obtained.

[(B) Preparation of ink]
After mixing the components shown in Tables 2 and 3 below, each of the inks of Examples 1 to 13 and Comparative Examples 1 to 4 were obtained by filtering with a 0.8 μm syringe filter. The balance was adjusted with ion-exchanged water so that the pigment solid content of each ink was 5%.

The abbreviations in Tables 2 and 3 below have the following meanings.
Tex: Texanol.
LPX: BYK LPX 23289.
EC: ADEKA COAL EC-8600.
DPGMPE: dipropylene glycol mono-n-propyl ether.
DEGDEE: diethylene glycol diethyl ether.
DEGMEE: diethylene glycol ethyl methyl ether.
DEGMBE: diethylene glycol mono-n-butyl ether.
DPGMME: dipropylene glycol monomethyl ether.
TPGMME: tripropylene glycol monomethyl ether.
EGMAE: ethylene glycol monoallyl ether.
EGMiPE: ethylene glycol monoisopropyl ether.
3M3MBA: 3-methoxy-3-methyl-1-butanol.
PGMPE: Propylene glycol mono-n-propyl ether.
PGMME: propylene glycol monomethyl ether.
DEGMiPE: diethylene glycol monoisopropyl ether.
TEGMBE: triethylene glycol mono-n-butyl ether.
DEGDBE: diethylene glycol di-n-butyl ether.
DPGDME: dipropylene glycol dimethyl ether.
DPG: dipropylene glycol.
TEG: triethylene glycol.
Dissolved amount: The dissolved amount of pure water measured in the above-mentioned "method of measuring the dissolved amount of pure water". Number is milliliter. "M" means that the solution was homogeneous even after adding 50 ml of pure water.

[(C) Measurement of dot diameter]
The inks of the above Examples and Comparative Examples were solid printed as 10% Duty images on a polyvinyl chloride sheet using an inkjet printer (trade name: PX205, manufactured by Seiko Epson Corporation). Then, the test piece for evaluation was obtained by drying in a 90 degreeC thermostat for 5 minutes.
The obtained test piece was observed with an optical microscope, and the dot diameter of each ink was measured.
The results are shown in Tables 2 and 3 above.

As is evident from the above results, it was confirmed that the inks of the examples obtained recorded images having a large dot diameter with respect to non-absorbing media.
In addition, the inks of Comparative Examples 1 and 2 were separated like oil droplets and floated on the surface of the ink. Therefore, the amount of DEGDBE and DPGDME was increased, but the state of separation was further deteriorated. For this reason, with respect to Comparative Examples 1 and 2, a dot diameter measurement test was performed with the composition shown in Table 3. As a result, it was found that the dot diameter was small. In addition, a state in which no solid was buried was observed, and it was found that the image quality was also poor. Further, it was found that the dot diameters of the inks of Comparative Examples 1 and 2 were extremely poor when the dot diameters were measured a plurality of times, and the values of the dot diameters varied. Although the reason is unknown, it was thought to be due to the fact that the ink was not in a uniform state. Therefore, the dot diameters of Comparative Examples 1 and 2 in Table 3 are numerical values for reference.

  With the ink of the present invention, a printed image having a large dot diameter can be obtained when attached to a recording medium, particularly a non-absorbing medium. That is, when the ink of the present invention is used, both the printing time and the ink consumption can be reduced. For this reason, the ink of the present invention is extremely useful as various recording inks, particularly as ink jet inks.

Claims (8)

An ink containing water, a water-insoluble colorant, a dispersant neutralized with ammonia, a compound represented by the following formula (1), and glycol ether,
An ink in which the glycol ether satisfies the following (I) to (III).
(I) The boiling point is 50 to 270 ° C.
(II) The number of hydroxy groups in one molecule is 0 or 1.
(III) The amount of pure water dissolved in 50 ml of glycol ether is greater than 5 ml.

(In the formula (1), R ¹ represents a hydroxy group, an alkoxy group having a hydroxy group, an acyloxy group, or an arylcarbonyloxy group, R ² represents a hydrogen atom or an alkyl group, and R ³ represents a hydrogen atom or an alkyl group. R ⁴ represents a hydrogen atom, a hydroxy group, or an alkyl group, and R ⁵ represents an alkyl group.)   2. The ink according to claim 1, wherein the glycol ether has a boiling point of 75 to 260 ° C.   The ink according to claim 1, wherein the glycol ether has a boiling point of 100 to 250C.   The ink according to claim 1, wherein the content of the compound represented by the formula (1) is 0.1 mass% to 5 mass% based on the total mass of the ink.   The ink according to any one of claims 1 to 4, further comprising a surfactant.   Use of the ink according to any one of claims 1 to 5 in inkjet recording.   An ink jet recording method for performing recording by discharging the ink droplets according to any one of claims 1 to 5 from an ink jet printer and attaching the ink droplets to a recording medium.   The inkjet recording method according to claim 7, wherein the recording medium is a medium selected from an ink non-absorbing medium and an ink hardly absorbing medium.