JP2018172621A - Ink set - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink set having yellow ink, magenta ink, cyan ink and black ink each formed of an ink that does not cause droplets discharged from an inkjet printer to generate tailing and satellite, exhibits good dischargeability both in an initial discharge and even when resuming continuous recording in intermittent recording.SOLUTION: There is provided an ink set having each ink of yellow, magenta, cyan and black each of which contains water, a water-insoluble coloring agent, propylene glycol, glycerol, an alkylene oxide adduct of diglycerol and has 5 mass%<a content of propylene glycol<15 mass%, 25 mass%<a content of glycerol<35 mass% and 0 mass%<a content of an alkylene oxide adduct of diglycerol<4 mass%, based on the total mass of each ink to solve the above-mentioned problem.SELECTED DRAWING: None

Description

  The present invention relates to an ink set containing water, a water-insoluble colorant, a specific amount of propylene glycol, glycerin, and an alkylene oxide adduct of diglycerin.

  Inkjet recording has become widespread as a printing method for offices and homes as information is digitized. In recent years, applications for commercial printing and textile printing have been promoted. As the use of ink jet recording expands, colorants used in ink jet inks also vary from water-soluble dyes (for example, acid dyes and direct dyes) to water-insoluble colorants (for example, disperse dyes and pigments). Etc.) has come to be used.

Generally, recorded images using water-soluble dyes are considered to have good image quality. On the other hand, a recorded image using a water-insoluble colorant is excellent in various fastness properties against light, ozone, water and the like. For this reason, water-insoluble colorants are preferably used in the field of commercial printing.
In an aqueous ink containing a water-insoluble colorant, the colorant is dispersed as a solid in the ink. For this reason, it is considered difficult to eject ink containing a water-insoluble colorant from an ink jet printer better than ink containing a water-soluble dye.
Also, substrates used for commercial printing often do not have an ink receiving layer. For this reason, the ink used for commercial printing for the purpose of improving the fixability of the colorant to the substrate often contains a resin. Furthermore, an ink containing a water-insoluble colorant is also dispersed by a resin. For this reason, in general, such an ink has a large solid content in the ink, which is one major factor that deteriorates the discharge performance.
In addition, ink jet printers used for commercial printing require high-viscosity inks compared to office and home printers because they need to print at high speed. The high viscosity of the ink is another factor that makes it difficult to ensure good ejection properties.
One evaluation method of the discharge property is a method of photographing the state of the discharged droplet and visually confirming the state of the droplet. In this method, when the droplets are in a spherical shape, the ejection property is evaluated as good. On the other hand, when the tail is generated in the droplet and / or when the droplet is separated into a plurality of satellites and the satellite is generated, the ejection property is evaluated as poor. By using this method, the state of the liquid droplets ejected from the ink jet printer can be directly evaluated.
In commercial printing, intermittent recording (continuous recording—recording repeatedly for several tens of minutes to several hours of temporary recording—repeating continuous recording) is performed for reasons such as breaks and holidays. There are many. When continuous recording is resumed after recording is temporarily stopped, there are many inks that have poor ejection properties. For this reason, in intermittent recording, there is a strong demand for ink that has good ejection properties even when continuous recording is resumed.
In general, inkjet recording obtains a full-color recorded image with four color ink sets of yellow, magenta, cyan, and black. However, it is also desired to obtain a higher-definition recorded image by adding an ink selected from blue, orange, and green to the four colors. For this reason, there is a strong demand for an ink set of four or more colors having the above-described characteristics and capable of obtaining a higher-definition recorded image.

  Inks containing a water-insoluble colorant are disclosed in, for example, Patent Documents 1 to 3.

Japanese Patent Laying-Open No. 2015-193742 International Publication 2014/084161 Gazette International Publication No. 2015/152290 Gazette

  An object of the present invention is an ink in which droplets ejected from an ink jet printer do not generate tails and satellites, and ink that has good ejection properties even when initial recording and continuous recording are resumed in intermittent recording. By providing an ink set further comprising one or more types of ink selected from the group consisting of yellow ink, magenta ink, cyan ink, and black ink, preferably selected from blue ink, orange ink, and green ink. is there.

  As a result of diligent research to solve the above problems, the present inventors contain water, a water-insoluble colorant, specific amounts of propylene glycol, glycerin, and an alkylene oxide adduct of diglycerin. The inventors have found that the above problems can be solved by yellow ink, magenta ink, cyan ink, and black ink, and have completed the present invention. That is, the present invention relates to the following 1) to 20).

1)
An ink set having yellow ink, magenta ink, cyan ink, and black ink each containing water, a water-insoluble colorant, propylene glycol, glycerin, and an alkylene oxide adduct of diglycerin, For the total mass of each ink,
Propylene glycol content is 5% by mass <propylene glycol <15% by mass,
The content of glycerin is 25% by mass <glycerin <35% by mass,
An ink set in which the content of an alkylene oxide adduct of diglycerin is 0% by mass <an alkylene oxide adduct of diglycerin <4% by mass.
2)
The ink set according to 1), wherein the alkylene oxide adduct of diglycerin is a compound represented by the following formula (1).

[In Formula (1), AL represents C2-C4 alkylene each independently, and j, k, m, and n represent the integer of 4-100 in total. ].
3)
The ink set according to 1), wherein each of the yellow ink, the magenta ink, the cyan ink, and the black ink further contains a dispersant.
4)
The dispersant is an AB block polymer;
The monomer constituting the A block is a monomer selected from benzyl methacrylate and benzyl acrylate,
The ink set according to 3), wherein the monomer constituting the B block is two or more types of monomers represented by the following formula (2).

[In Formula (2), R ¹ represents a hydrogen atom or an alkyl group, and R ² represents a hydrogen atom or a methyl group. ].
5)
The monomer constituting the A block is benzyl methacrylate,
Among the monomers represented by the formula (2), the monomer constituting the B block is:
A monomer in which R ¹ is a hydrogen atom and R ² is a methyl group;
The ink set according to 4), wherein R ¹ is a C4 alkyl group and R ² is a monomer represented by a methyl group.
6)
The ink set according to 1), wherein the water-insoluble colorant is a pigment.
7)
The pigment is C.I. I. The ink set according to 6) above, which is a pigment selected from pigment and carbon black.
8)
The water-insoluble colorant contained in the yellow ink is C.I. I. Pigment yellow,
The water-insoluble colorant contained in the magenta ink is C.I. I. Pigment red,
The water-insoluble colorant contained in the cyan ink is C.I. I. Pigment blue, and the hue angle Hc ° is 240 ≦ Hc ° <270,
The ink set according to 1) or 3), wherein the water-insoluble colorant contained in the black ink is carbon black.
9)
The ink set according to 1), further including at least one kind of ink selected from blue ink, orange ink, and green ink.
10)
Each of the blue ink, the orange ink, and the green ink is an ink containing water, a water-insoluble colorant, propylene glycol, glycerin, and an alkylene oxide adduct of diglycerin. For the total mass of the ink,
Propylene glycol content is 5% by mass <propylene glycol <15% by mass,
The content of glycerin is 25% by mass <glycerin <35% by mass,
The ink set according to 9), wherein the content of the alkylene oxide adduct of diglycerin is 0% by mass <the alkylene oxide adduct of diglycerin <4% by mass.
11)
The ink set according to 10), wherein each of the blue ink, the orange ink, and the green ink further contains a dispersant.
12)
The dispersant is an AB block polymer;
The monomer constituting the A block is a monomer selected from benzyl methacrylate and benzyl acrylate,
The ink set according to 11), wherein the monomer constituting the B block is two or more types of monomers represented by the following formula (2).

[In Formula (2), R ¹ represents a hydrogen atom or an alkyl group, and R ² represents a hydrogen atom or a methyl group. ].
13)
The monomer constituting the A block is benzyl methacrylate,
Among the monomers represented by the formula (2), the monomer constituting the B block is:
A monomer in which R ¹ is a hydrogen atom and R ² is a methyl group;
The ink set according to 12), wherein R ¹ is a C4 alkyl group and R ² is a monomer represented by a methyl group.
14)
The water-insoluble colorant contained in the blue ink is C.I. I. Pigment blue, and the hue angle Hb ° is 270 ≦ Hb ° ≦ 330,
The water-insoluble colorant contained in the orange ink is C.I. I. Pigment orange,
The water-insoluble colorant contained in the green ink is C.I. I. The ink set according to any one of 9) to 11), which is CI Pigment Green.
15)
The ink set according to any one of 1), 3), and 8), wherein a hue angle Hy ° of the yellow ink is 80 ≦ Hy ° ≦ 110.
16)
The ink set according to any one of 1), 3), and 8), wherein a hue angle Hm ° of the magenta ink is either 355 ≦ Hm ° ≦ 360 or 0 ≦ Hm ° ≦ 15.
17)
The ink set according to any one of 9) to 11) or 14), wherein the hue angle Ho ° of the orange ink is 15 <Ho ° <80.
18)
The ink set according to any one of 9) to 11) or 14), wherein a hue angle Hg ° of the green ink is 120 ≦ Hg ° ≦ 200.
19)
Inkjet recording by ejecting one or more ink droplets selected from the ink set according to any one of 1) to 18) according to a recording signal and adhering to the substrate. Recording method.
20)
A substrate to which one or more kinds of inks selected from the ink set according to any one of 1) to 18) are attached.

  According to the present invention, the droplets ejected from the ink jet printer are inks that do not produce tails and satellites, and are composed of inks that have good ejection properties even when intermittent recording is resumed in intermittent recording together with initial ejection. An ink set having one or more inks selected from yellow ink, magenta ink, cyan ink and black ink, preferably selected from blue ink, orange ink and green ink could be provided.

Unless otherwise specified, in this specification, “%” and “parts” including examples and the like are both described on a mass basis. “CI” means a color index.
The ink set is an ink set made of a water-based ink containing water.
In addition, in this specification, when describing matters common to each ink of yellow, magenta, cyan, black, and, if necessary, blue, orange, and green included in the ink set, unless otherwise specified. It is described as “the ink” or “ink”.

[Water-insoluble colorant]
In this specification, the water-insoluble colorant means a colorant having a solubility in water at 25 ° C. of usually 3 g / liter or less, preferably 1 g / liter or less, more preferably 500 mg / liter or less, and further preferably 100 mg / liter or less. Is mentioned.
Such colorants include C.I. I. Disperse, C.I. I. Colorants selected from solvents and pigments can be mentioned. Of these, pigments are preferred. Examples of the pigment include inorganic pigments, organic pigments, extender pigments, and the like.

Examples of the inorganic pigment include carbon black, metal oxide, metal hydroxide, metal sulfide, ferrocyanide, and metal chloride. Among these, carbon black is preferable as the black pigment.
Examples of carbon black include thermal black, acetylene black, oil furnace black, gas furnace black, lamp black, gas black, and channel black. Among these, acetylene black, oil furnace black, gas furnace black, lamp black, and channel black are preferable.
Specific examples of carbon black include, for example, the Raven series manufactured by Columbian Carbon; the Monarch series, Regal series, and Mogul series manufactured by Cabot; the Color Black series, the Printex series, the Special Black series manufactured by Degussa; Examples include MA series and MCF series manufactured by the company.

Examples of organic pigments include azo pigments having at least one azo group in the molecule, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, dioxazine pigments, perylene pigments, perinone pigments, thioindigo pigments, anthraquinone pigments, and quinophthalone pigments. Can be mentioned. Among these, C.I. I. Pigments selected from pigments are preferred.
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, 139, 150, 151, 154, 155, 180, 185, 193, 199, 202; 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, 254, 255, 257, 260, 264, 272; I. Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 22, 25, 60, 66, 80; I. Pigment violet 19, 23, 29, 37, 38, 50; and C.I. I. Pigment black 1, 7 and the like.

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

Examples of the water-insoluble colorant include C.I. I. Pigments selected from pigments and carbon black are preferred.
The water-insoluble colorant contained in the yellow ink is C.I. I. Pigment Yellow is preferable, and the hue angle Hy ° is more preferably 80 ≦ Hy ° ≦ 110.
The water-insoluble colorant contained in the magenta ink is C.I. I. Pigment Red is preferable, and the hue angle Hm ° is more preferably 355 ≦ Hm ° ≦ 360 or 0 ≦ Hm ° ≦ 15.
Here, the hue angles of 360 and 0 mean the same hue angle.
The water-insoluble colorant contained in the cyan ink is C.I. I. Pigment Blue is preferable, and the hue angle Hc ° is preferably 240 ≦ Hc ° <270.
The water-insoluble colorant contained in the black ink is preferably carbon black.
The hue angle can be calculated by the method described in the examples. It is also possible to calculate from the measured values of a * and b * using the calculation function of the colorimeter. These numerical values are the same value. In the present specification, a * and b * are measured by the method described in the examples, and the method for calculating the hue angle may be either the method described in the examples or the method described above.

  The ink set preferably further includes one or more types of ink selected from blue ink, orange ink, and green ink. By using an ink set of five or more colors having these inks, a high-definition recorded image that cannot be realized with a four-color ink set can be obtained.

The water-insoluble colorant contained in the blue ink is C.I. I. Pigment Blue is preferable, and the hue angle Hb ° is preferably 270 ≦ Hb ° ≦ 330.
The water-insoluble colorant contained in the orange ink is C.I. I. Pigment Orange is preferable, and the hue angle Ho ° is more preferably 15 <Ho ° <80.
The water-insoluble colorant contained in the green ink is C.I. I. Pigment Green is preferable, and the hue angle Hg ° is more preferably 120 ≦ Hg ° ≦ 200.

A hue angle Hb ° of 270 ≦ Hb ° ≦ 330; I. As the pigment blue, the C.I. I. A mixture of two or more colorants selected from pigment blue, or C.I. I. Pigment blue 15: 6.
C. I. Pigment orange includes C.I. I. Pigment orange 13, 16, 34, 36, 43, 68, 69, 71, 73 and the like.
C. I. Pigment Green includes C.I. I. Pigment green 7, 36, 54, and the like.

The ink can contain one or more water-insoluble colorants. Examples of the purpose of using two or more colorants in combination include improvement of fluidity when the colorant is powdered, and adjustment of hue (preferably adjustment of hue angle).
The content of the colorant relative to the total mass of the ink is usually 1% to 30%, preferably 1% to 15%, more preferably 2% to 10%.

[Propylene glycol]
The ink contains propylene glycol. The content is usually 5% <propylene glycol <15%, preferably 6% ≦ propylene glycol ≦ 14%, more preferably 7% ≦ propylene glycol ≦ 13% with respect to the total mass of the ink.

[Glycerin]
The ink contains glycerin. The content is usually 25% <glycerin <35%, preferably 26% ≦ glycerin ≦ 34%, more preferably 27% ≦ glycerin ≦ 33% with respect to the total mass of the ink.

[Alkylene oxide adduct of diglycerin]
The ink contains an alkylene oxide adduct of diglycerin. The content thereof is usually 0% based on the total mass of the ink <alkylene oxide adduct of diglycerin <4%, preferably 0.1% ≦ alkylene oxide adduct of diglycerin ≦ 3%, more preferably 0.8%. 3% ≦ alkylene oxide adduct of diglycerol ≦ 3%, more preferably 0.5% ≦ alkylene oxide adduct of diglycerin ≦ 2.5%.
As the alkylene oxide adduct of diglycerin, the compound represented by the formula (1) is preferable. In addition, the compound represented by Formula (1) is a mixture of a compound substantially represented by Formula (1).
In formula (1), the C2-C4 alkylene in AL includes a straight chain, a branched chain, and a cyclic alkylene. Of these, linear or branched alkylene is preferable. The preferred carbon number range is C2-C3, more preferably C3.
In formula (1), the sum total of j, k, m, and n is 4-100 normally, Preferably it is 4-90. The weight average molecular weight of these compounds is usually 300 to 5,000, preferably 400 to 4,500, more preferably 450 to 3,000, still more preferably 700 to 2,000, sometimes 750 to 1,600, particularly preferably 750 to 1200. is there. The weight average molecular weight can be measured by GPC (gel permeation chromatography).
Specific examples thereof include, for example, SC-P400 (4/400), SC-P750 (9/750), SC-P1000 (14/1000), SC-P1200 (18/1200) manufactured by Sakamoto Pharmaceutical Co., Ltd. SC-P1600 (24/1600); SC-E450 (6/450), SC-E750 (13/750), SC-E1000 (20/1000), SC-E1500 (30/1500), SC-E2000 ( 40/2000), SC-E3000 (60/3000), SC-E4500 (90/4500); Unilube DGP-700 (9/700), DGP-700F, etc. manufactured by NOF Corporation.
Among the above, the series of “SC-P” and “DGP” are compounds in which AL in the formula (1) is branched C3 alkylene, and the series of “SC-E” is a compound in which AL is linear C2 alkylene. Further, the parentheses in each specific example mean (average value of the sum of k + j + m + n / weight average molecular weight).

  By setting the content of the alkylene oxide adduct of propylene glycol, glycerin, and diglycerin in the ink within the above range, an ink that can solve the above problems can be obtained.

[Dispersant]
The ink preferably further contains a dispersant. Examples of the dispersant include known dispersants. Examples include styrene and derivatives thereof; vinyl naphthalene and derivatives thereof; aliphatic alcohol esters of α, β-ethylenically unsaturated carboxylic acids; (meth) acrylic acid and derivatives thereof; maleic acid and derivatives thereof; At least two monomers (preferably selected from the group consisting of: derivatives thereof; furic acid and derivatives thereof; vinyl acetate, vinyl alcohol, vinyl pyrrolidone, (meth) acrylamide, and derivatives thereof; , And at least one of these is a hydrophilic monomer).
In this specification, “(meth) acrylic acid” is used to mean “both acrylic acid and methacrylic acid”. “(Meth) acrylamide” and the like are also used with the same meaning.
As a kind of copolymer, a block copolymer, a random copolymer, a graft copolymer, and / or their salts are mentioned, for example.
The dispersant can be synthesized or obtained as a commercial product. Specific examples of commercially available products include, for example, styrene-acrylic resins such as Jonkrill 62, 67, 68, 678, and 687 manufactured by Johnson Polymer Co., Ltd .; Vinyl S-100A (modified vinyl acetate manufactured by Hoechst Chemical Co., Ltd.) Resin); Jurimer AT-210 (polyacrylic acid ester copolymer manufactured by Nippon Pure Chemical Co., Ltd.) and the like.
Among these, the monomer constituting the A block is a monomer selected from benzyl methacrylate and benzyl acrylate, and the monomer constituting the B block is two or more types of monomers represented by the formula (2), -B block polymers are preferred.
The monomer constituting the A block is benzyl methacrylate, and the monomer constituting the B block is a monomer represented by the formula (2), wherein R ¹ is a hydrogen atom and R ² is a methyl group. And an AB block polymer, which is two types of a monomer in which R ¹ is a C4 alkyl group and R ² is a methyl group, is more preferable.
As such AB block polymer, the dispersing agent disclosed by the international publication 2013/115071 gusset is mentioned, for example.

  The weight average molecular weight (Mw) of the dispersant is not particularly limited, but is usually 3000 to 50000, preferably 7000 to 45000, more preferably 10,000 to 40000, still more preferably 15000 to 30000, and particularly preferably 17000 to 27000. The acid value is usually 50 to 300 KOH mg / g, preferably 60 to 250 KOH mg / g, more preferably 70 to 200 KOH mg / g, still more preferably 80 to 150 KOH mg / g, and particularly preferably about 100 to 120 KOH mg / g. .

The dispersant can be used in a state mixed with a colorant. Moreover, it can also be used as the state which coat | covered the dispersing agent on the surface of a coloring agent. Moreover, both of these can also be used together.
When using a dispersant, the ratio of the amount of dispersant used relative to the total mass of the colorant is usually 0.1 to 1.0, preferably 0.1 to 0.6, more preferably 0.2 to 0.4. It is. When the ratio of the amount of the dispersant used is in this range, a pigment dispersion having excellent stability can be obtained.

  When a water-insoluble colorant is used, the average particle size is usually 5 nm to 300 nm, preferably 50 nm to 200 nm, more preferably 60 nm to 120 nm. By setting the average particle size within this range, it is possible to improve the storage stability, dischargeability, and print density (reflection density) of the dispersion. The average particle size can be measured using laser light scattering.

The ink is preferably prepared by preparing a dispersion containing a colorant and a dispersant and then mixing it with other components. The dispersion can be prepared by a known method.
As an example, a dispersant is dissolved in an organic solvent such as 2-butanone, and in the case of an anionic dispersant, an aqueous solution of a neutralizing agent is added to prepare an emulsion. A colorant is added to the obtained emulsion to disperse it to obtain a liquid. A dispersion containing a colorant can be obtained by distilling off the organic solvent and part of the water under reduced pressure from the liquid thus obtained.
In the dispersion treatment, for example, the dispersion solution or emulsion and the colorant are dispersed in a sand mill (bead mill), roll mill, ball mill, paint shaker, ultrasonic disperser, microfluidizer, or the like. When using a sand mill, beads having a particle diameter of about 0.01 mm to 1 mm can be used. The efficiency of the dispersion treatment can be adjusted by adjusting the filling rate of beads, the dispersion time, the content of the colorant, and the like.
The dispersion obtained as described above can be filtered and / or centrifuged so that the particle diameters of the contained particles can be set within a certain range.

The ink may further contain one or more water-soluble organic solvents as components other than those described above, if necessary. Examples of such water-soluble organic solvents include C1-C4 monools such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, and tert-butanol; ethylene glycol, 1, 3 -C2-C6 diols such as propanediol, 1,2- or 1,4-butanediol, 1,3-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol; hexane C3-C6 triols such as -1,2,6-triol and trimethylolpropane; carboxylic acid amides such as N, N-dimethylformamide and N, N-dimethylacetamide; 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethylimidazolidin-2-one, 1,3-dimethylhexa Nitrogen-containing heterocyclic compounds such as dropyrimido-2-one; ketones or ketoalcohols such as acetone, methyl ethyl ketone, 2-methyl-2-hydroxypentan-4-one; chain structures such as 1,2-dimethoxyethane, tetrahydrofuran, dioxane Or cyclic ether; di- or tri-C2-C3 alkylene glycol or thioglycol such as diethylene glycol, triethylene glycol, dipropylene glycol, thiodiglycol; tetraethylene glycol, polyethylene glycol (preferably having a molecular weight of 400, 800, 1540, etc.) Having a repeating unit of 4 or more and a molecular weight of about 20000 or less (preferably liquid); Polyglyceryl ethers such as phosphorus, triglycerin, polyglycerin; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether Alkyl ethers of polyhydric alcohols (preferably C1-C6 alkyl ethers); cyclic esters or carbonates such as γ-butyrolactone and ethylene carbonate; dimethyl sulfoxide; acetic acid and the like.
When the ink further contains these water-soluble organic solvents, the total content of these water-soluble organic solvents is usually 0% to 55%, preferably 0% to 40% with respect to the total mass of the water-soluble organic solvent. More preferably, it is 0% to 30%, more preferably 0% to 20%, particularly preferably about 0% to 10%. When the total content is within such a range, it is possible to maintain a good ink ejection property.

The ink may further contain one or more components other than those described above as ink preparation agents. Examples of the ink preparation agent include antiseptic / antifungal agents, pH adjusters, chelating reagents, rust inhibitors, water-soluble ultraviolet absorbers, water-soluble polymer compounds, antioxidants, surfactants, and the like.
The total content of the ink preparation agent with respect to the total mass of the ink is usually about 0% to 5%, preferably about 0.1% to 3%.

  Examples of the antifungal agent include sodium dehydroacetate, sodium benzoate, sodium pyridinethione-1-oxide, p-hydroxybenzoic acid ethyl ester, 1,2-benzisothiazolin-3-one and salts thereof.

Examples of preservatives include organic sulfur, organic nitrogen sulfur, organic halogen, haloaryl sulfone, iodopropargyl, haloalkylthio, nitrile, pyridine, 8-oxyquinoline, benzothiazole, Isothiazoline, dithiol, pyridine oxide, nitropropane, organotin, phenol, quaternary ammonium salt, triazine, thiazine, anilide, adamantane, dithiocarbamate, brominated indanone, benzyl brom Acetate-based and inorganic salt-based compounds are exemplified.
An example of the organic halogen compound is sodium pentachlorophenol. Examples of pyridine oxide compounds include sodium 2-pyridinethiol-1-oxide. Examples of the isothiazoline-based compound include 1,2-benzisothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, 5 -Chloro-2-methyl-4-isothiazolin-3-one magnesium chloride, 5-chloro-2-methyl-4-isothiazolin-3-one calcium chloride, 2-methyl-4-isothiazolin-3-one calcium chloride, etc. Can be mentioned.
Examples of other antiseptic / antifungal agents include anhydrous sodium acetate, sodium sorbate, sodium benzoate, and proxel series such as Proxel GXL (S) and XL-2 (S) manufactured by Arch Chemical Co., Ltd.

As the pH adjuster, any substance can be used as long as it can control the pH of the ink within the range of 5 to 11 without adversely affecting the prepared ink. Examples thereof include alkali metal hydroxides, alkaline earth metal hydroxides, inorganic bases such as ammonia, and organic bases such as aliphatic amine compounds and alkanolamine compounds.
In these, an organic base is preferable and an alkanolamine compound is more preferable.
Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, and potassium hydroxide.
Examples of the alkaline earth metal hydroxide include beryllium hydroxide, magnesium hydroxide, calcium hydroxide, and strontium hydroxide.
Among the inorganic bases, alkali metal hydroxides and ammonia are preferable. Among these, lithium hydroxide, sodium hydroxide, and ammonia are preferable.
Examples of the aliphatic amine compound include mono-, di-, and tri-C1-C3 amine compounds such as monomethylamine, dimethylamine, trimethylamine, monoethylamine, dimethylamine, and trimethylamine. Of these, triethylamine is preferred.
Examples of the alkanolamine compound include monoethanolamine, diethanolamine, triethanolamine, monopropanolamine, dipropanolamine, tripropanolamine, methylethanolamine, dimethylethanolamine, N-methyldiethanolamine and other mono, di, or tri C1- A C3 alkanolamine compound is mentioned. Among these, tertiary amines are preferable, and triethanolamine is particularly preferable.
Other examples include, for example, alkali metal carbonates such as lithium carbonate, sodium carbonate, sodium bicarbonate and potassium carbonate; alkali metal salts of organic acids such as sodium silicate and potassium acetate; phosphorus such as disodium phosphate Acid salt; and the like.

  Examples of the chelating reagent include disodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, sodium uracil diacetate, and the like.

  Examples of the rust inhibitor include acidic sulfite, sodium thiosulfate, ammonium thioglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite.

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

  Examples of the water-soluble polymer compound include polyvinyl alcohol, cellulose derivatives, polyamines and polyimines.

  As the antioxidant, for example, various organic and metal complex antifading agents can be used. Examples of the organic anti-fading agent include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, and heterocyclic rings.

Examples of the surfactant include known surfactants such as anion, cation, nonion, amphoteric, silicone-based and fluorine-based. Of these, nonionic surfactants are preferred.
Examples of anionic surfactants include alkyl sulfocarboxylates, α-olefin sulfonates, polyoxyethylene alkyl ether acetates, polyoxyethylene alkyl ether sulfates, N-acyl amino acids or salts thereof, N-acyl methyl taurate, Alkyl sulfate polyoxyalkyl ether sulfate, alkyl sulfate polyoxyethylene alkyl ether phosphate, rosin acid soap, castor oil sulfate ester, lauryl alcohol sulfate ester, alkylphenol type phosphate ester, alkyl type phosphate ester, Examples thereof include alkylaryl sulfonates, diethylsulfosuccinates, diethylhexylsulfosuccinates, dioctylsulfosuccinates and the like.

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

  Nonionic surfactants include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether, and other ethers; poly Esters such as oxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, polyoxyethylene stearate; 2 4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 3,5-dimethyl -1-hexyn-3-ol, Surfynol 104, 104PG50, 82, 420, 440, 465, 485, olphine STG, and other acetylene glycol (alcohol) series and their C2-C4 alkylene Examples include oxyadducts; polyglycol ether type (eg, Tergitol 15-S-7 manufactured by SIGMA-ALDRICH). Among these, acetylene glycol type is preferable, and Surfynol series is more preferable.

  Examples of amphoteric surfactants include lauryldimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, coconut oil fatty acid amidopropyldimethylaminoacetic acid betaine, polyoctylpolyaminoethylglycine, and imidazoline derivatives. Can be mentioned.

  Examples of silicone surfactants include polyether-modified siloxane and polyether-modified polydimethylsiloxane. As an example, Dynol 960, 980 manufactured by Air Products, Inc., Silface SAG001, SAG002, SAG003, SAG005, SAG503A, SAG008, SAG009, SAG010 manufactured by Nissin Chemical Co., Ltd .; BYK-345 manufactured by BYK Chemie, 347, 348, 349, 3455 and the like.

  Examples of the fluorosurfactant include a perfluoroalkyl sulfonic acid compound, a perfluoroalkyl carboxylic acid compound, a perfluoroalkyl phosphate ester compound, a perfluoroalkyl ethylene oxide adduct, and a perfluoroalkyl ether group as a side chain. And polyoxyalkylene ether polymer compounds. As the fluorosurfactant, various types of products can be easily purchased from, for example, DuPont, Omniva, DIC, and Big Chemie.

The pH of the ink is usually pH 5 to 11, preferably pH 7 to 10, for the purpose of improving storage stability.
The surface tension of the ink at 25 ° C. is usually 10 mN / m to 50 mN / m, preferably 20 mN / m to 40 mN / m.
The viscosity of the ink at 28 ° C. is usually 4 mPa · s to 20 mPa · s, preferably 6 mPa · s to 15 mPa · s. When used as an inkjet ink for commercial printing, 8 to 13 mPa · s is more preferable, and 10 mPa · s to 12 mPa · s is particularly preferable.
These physical property values can be adjusted with, for example, a pH adjuster, a water-soluble organic solvent, and a surfactant.

  The ink set can be used for various recording and printing. For example, it is suitable for applications such as writing, printing, information recording, and textile printing. Among these, it is preferable to use for inkjet recording, particularly for commercial printing.

  The ink jet recording method is a method of performing recording by ejecting one or more ink droplets selected from the ink set in accordance with a recording signal and attaching them to a substrate. The inkjet recording method is not particularly limited, and various known methods can be used. Examples of the ink jet recording method 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. Among these, the drop on demand method is preferable.

  The substrate is not particularly limited as long as it is a substance colored by the ink. Examples thereof include fiber; paper having an ink-receiving layer; and a non-ink-absorbing or non-ink-absorbing substrate that does not have an ink-receiving layer. Examples of the ink-absorptive substrate include plain paper, media used for gravure printing and offset printing, art paper, coated paper, matte paper, cast paper, and the like. Examples of the non-ink-absorbing substrate include a vinyl chloride sheet, a polymer sheet, glass, and rubber. In these, the fiber, the paper which has an ink receiving layer, and the base material which does not have an ink receiving layer and hardly absorbs ink is preferable.

When a base material is a fiber, the fiber selected from the group which consists of polyester, a cellulose, polyamide, and a natural fiber, and the mixed fiber containing these fibers are mentioned. These fibers can have an ink receiving layer. The ink receiving layer can be provided on the fiber by a known method. The fiber having the ink receiving layer is commercially available, for example, in the form of a fabric.
Polyester fibers include polyethylene terephthalate fibers.
Cellulose fibers include fibers such as cotton, rayon, triacetate, and diacetate.
Examples of polyamide fibers include nylon fibers.
Examples of natural fibers include silk and wool.

When the substrate is a fiber, baking treatment can be performed on the fiber to which the ink droplets are attached.
The baking (thermosol) treatment is usually performed at a temperature of 80 to 250 ° C., preferably 160 to 180 ° C., usually for 10 seconds to 30 minutes, preferably about 60 to 180 seconds.

  About all the above-mentioned matters, a combination of preferable ones is more preferable, and a combination of more preferable ones is further preferable. The same applies to combinations of preferable and more preferable ones.

The ink set is an ink set having ink in which droplets ejected from an ink jet printer do not generate tails and satellites. Further, the ink set has a high viscosity suitable for an inkjet printer for commercial printing.
The ink set is good in filling each ink into the ink jet head. In addition, there is no ejection bending or blurring during ink jet recording, and stable ejection can be achieved.
The ink set does not clog the nozzles of the print head in both continuous recording for a long time and intermittent recording.
The ink set has good storage stability during storage. Even if water or the like in any of the inks is lost and the ink is dried to produce solids, the solids can be easily redispersed by an operation similar to replenishment of ink.
With the ink set, a recorded image with no color bleeding and high color can be obtained.
With the ink set, recorded images having various fastness properties such as light resistance and water resistance can be obtained.

Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to the examples.
“Water” used in the examples is ion-exchanged water.
In Examples, when it was necessary to measure the content of the colorant in the dispersion, it was determined by a dry weight method using MS-70 manufactured by A & D Corporation. The content of the colorant is a converted value from the total content of solids contained in the dispersion.

[Preparation Example 1]: Synthesis of dispersant.
According to “[Synthesis Example 3] Synthesis of Block Copolymer A” of International Publication No. 2013/115071, 138 g of a dispersant having an Mw of 24,300 and a PDI of 1.49 was obtained. In the obtained dispersant, the monomer constituting the A block is benzyl methacrylate, the monomer constituting the B block is a monomer represented by the formula (2), R ¹ is a hydrogen atom, and R ² is a methyl group And a monomer in which R ¹ is an n-butyl group as a C4 alkyl group and R ² is a methyl group.

[Preparation Example 2]: Preparation of a dispersion containing a colorant.
The dispersant (6.3 parts) obtained in Preparation Example 1 was dissolved in 2-butanone (20 parts) to obtain a solution. To this solution, a solution obtained by dissolving 0.47 parts of sodium hydroxide in water (51.45 parts) was added and stirred for 1 hour to obtain an emulsion. To the resulting liquid, C.I. I. Pigment Yellow 155 (21 parts) was added, and the mixture was dispersed with a sand grinder for 15 hours under water cooling to obtain a liquid. The obtained liquid was diluted with ion-exchanged water, and the beads for dispersion were separated by filtration (two sheets of glass filter paper manufactured by Advantech Co., Ltd. were stacked so that GA100 is on and GC50 is on the bottom) to obtain a filtrate. A part of 2-butanone and water in the obtained filtrate was distilled off under reduced pressure with an evaporator to obtain a dispersion having a colorant content of 12%, which is referred to as “dispersion 1”. .

[Preparation Examples 3 to 9] Preparation of a dispersion containing a colorant.
Dispersions 2 to 8 of Preparation Examples 3 to 9 were obtained in the same manner as Preparation Example 2 except that the respective components used in Preparation Example 2 were replaced with the components and amounts used in Table 1 below. . In addition, the numerical value of each component is “parts”, and the amount of water added was adjusted so that the total content of the colorant in each dispersion was 12%.

Abbreviations and the like in Table 1 below represent the following meanings.
PY155 = C.I. I. Pigment Yellow 155.
PR122 = C. I. Pigment Red 122 (manufactured by Clariant, INKJET MAGENTA E-02).
PR150 = C. I. Pigment Red 150.
PB15: 4 = C. I. Pigment Blue 15: 4.
CB = carbon black.
PB15: 6 = C. I. Pigment Blue 15: 6.
PO43 = C. I. Pigment Orange 43.
PG36 = C. I. Pigment Green 36.
Dp = Dispersant prepared in Preparation Example 1 above.
MEK = 2-butanone.
NaOH = sodium hydroxide.
DP No. = Number of dispersion prepared in Preparation Examples 2-9 above.
DP1 to DP8 = Dispersions 1 to 8 prepared in Preparation Examples 2 to 9 above.

Examples 1 to 21: Preparation of ink.
After mixing each component of the following Tables 2-4, and stirring sufficiently, it filtered with a 5-micrometer membrane filter, and obtained the ink of Examples 1-21 used for an evaluation test. The numerical value of each component is “parts”, and the amount of water added was adjusted so that the total was 100 parts.

[Comparative Examples 1-6]
Comparative inks of Comparative Examples 1 to 6 were obtained in the same manner as in Examples 1 to 21 except that each component described in Table 5 below was used.

The abbreviations in the following Tables 2 to 5 have the following meanings.
DP1 to DP8 = Dispersions 1 to 8 prepared in Preparation Examples 2 to 9 above.
UX-320 = Yukot UX-320.
PG = propylene glycol.
GL = glycerin.
DGA = alkylene oxide adduct of diglycerin. SC-P1000 was used.
TEA = 90% triethanolamine (the balance is water).
SF420 = Surfinol 420.
GXL = Proxel GXL (S).

[Drop state test]
Using an industrial inkjet head evaluation apparatus (expandable coating apparatus EV2500, manufactured by Ricoh Co., Ltd.), droplets of the inks of Examples and Comparative Examples were ejected, and a photograph of the droplets was taken every 4 microseconds. The droplets were ejected by setting the heater built in the head to 28 ° C., a head drive voltage of 14.0 V, and a frequency of 2 kHz. The state of the droplet when the ink droplet flew 1 mm was confirmed with the photograph taken and evaluated according to the following four evaluation criteria A to D. The test results are shown in Tables 6 to 8 below.
[Evaluation criteria]
A: Tail and satellite are not recognized in ink droplet.
B: Either a tail or a satellite is observed in the ink droplet.
C: Both tails and satellites are observed in the ink droplets.
D: The ink droplets are ejected in a scattered state.

[Initial discharge test]
Using the industrial inkjet head evaluation apparatus, a nozzle check pattern was inkjet recorded on the substrate described below. Recording was performed at a head drive voltage of 14.0 V and 10 kHz with the head built-in heater set at 28 ° C. The recorded image of the printed matter was confirmed and evaluated according to the following four evaluation criteria A to D.
[Base material]
Canon Photo Paper Pro Platinum PT-101 or EPSON photo paper <glossy>, model number: KA4100PSKR was arbitrarily used. There was no difference in the state of the nozzle check pattern recorded on these substrates.
[Evaluation criteria]
A: “Fuzz” is not recognized at all in the recorded image.
B: When the recorded image is observed in detail, slight “fading” is recognized.
C: “Fuzzy” is observed in the recorded image.
D: The recorded image is clearly “smooth”.

[Intermittent recording test]
In the same manner as in [Initial Discharge Test], the nozzle check pattern was ink jet recorded on the substrate, and then the recording was stopped. After leaving the industrial inkjet head evaluation apparatus for 30 minutes in the state as it is, the nozzle check pattern is inkjet-recorded again on the substrate, the state of the recorded image is visually confirmed, and the following four grades A to D are evaluated. Evaluated by criteria.
[Evaluation criteria]
A: “Fuzz” is not recognized at all in the recorded image.
B: When the recorded image is observed in detail, slight “fading” is recognized.
C: “Fuzzy” is observed in the recorded image.
D: The recorded image is clearly “smooth”.

Abbreviations and the like in the following Tables 6 to 8 have the following meanings.
Color = ink color.
Y = yellow ink.
M = magenta ink.
C = Cyan ink.
K = black ink.
B = Blue ink.
O = Orange ink.
G = Green ink.
Droplet = [Drop state test] as described above.
PG = content of propylene glycol relative to the total mass of the ink.
GL = content of glycerin relative to the total mass of the ink.
DGA = content of diglycerin alkylene oxide adduct relative to the total mass of the ink.

As is clear from the results in Tables 6 to 8, all of the inks of the examples are A or B. On the other hand, in the ink of the comparative example, either evaluation was C or D, and it was confirmed that the example was excellent.
The initial ejection and intermittent recording of Comparative Examples 1 and 3 were “A” in the evaluation criteria. However, in these recorded images, the ink is scattered, and the portion that should be white is also colored. That is, the inks of Comparative Examples 1 and 3 were unable to perform ink jet recording of a normal nozzle check pattern in both initial ejection and intermittent recording.

[Measurement of hue angle]
Using the ink-jet printer PX-205 manufactured by Seiko Epson Corporation, each ink of the example is printed on EPSON photo paper (KA420PSK) at a print quality condition of “clean” and color correction “none” at 100% density. A solid image was printed. Using the spectrophotometer SpectroEye manufactured by Sakata Inx Engineering Co., Ltd., the obtained solid image was set to 6 for a * and b * under the setting conditions of light source D65, 2 ° field of view, density standard ANSI Status A, use function CIE Lab. The color was measured once and the average value was put into the following calculation formula to calculate the hue angle H °. The calculation results are shown in Table 9 below.
Note that a * and b * are used to calculate the hue angle by measuring up to the second digit after the decimal point, and the calculation result is a value obtained by rounding off the first digit after the decimal point.
[Calculation formula of hue angle]
Hue angle H ° = tan ⁻¹ (b * / a *) + 180: Calculation formula when a * <0.
Hue angle H ° = tan ⁻¹ (b * / a *) + 360: calculation formula when a *> 0.
Hue angle H ° = tan ⁻¹ (b * / a *): a calculation formula when a *> 0 and b *> 0.

  The ink set of the present invention is an ink in which droplets ejected from an ink jet printer do not produce tails and satellites, and has good ejection properties even when initial recording and continuous recording are resumed in intermittent recording. Ink set comprising yellow ink, magenta ink, cyan ink and black ink, preferably an ink set further comprising one or more types of ink selected from blue ink, orange ink and green ink, It is extremely useful as an inkjet ink.

Claims (20)

An ink set having yellow ink, magenta ink, cyan ink, and black ink each containing water, a water-insoluble colorant, propylene glycol, glycerin, and an alkylene oxide adduct of diglycerin, For the total mass of each ink,
Propylene glycol content is 5% by mass <propylene glycol <15% by mass,
The content of glycerin is 25% by mass <glycerin <35% by mass,
An ink set in which the content of an alkylene oxide adduct of diglycerin is 0% by mass <an alkylene oxide adduct of diglycerin <4% by mass. The ink set according to claim 1, wherein the alkylene oxide adduct of diglycerin is a compound represented by the following formula (1).

[In Formula (1), AL represents C2-C4 alkylene each independently, and j, k, m, and n represent the integer of 4-100 in total. ].   The ink set according to claim 1, wherein each of the yellow ink, magenta ink, cyan ink, and black ink further contains a dispersant. The dispersant is an AB block polymer;
The monomer constituting the A block is a monomer selected from benzyl methacrylate and benzyl acrylate,
The ink set according to claim 3, wherein the monomers constituting the B block are two or more types of monomers represented by the following formula (2).

[In Formula (2), R ¹ represents a hydrogen atom or an alkyl group, and R ² represents a hydrogen atom or a methyl group. ]. The monomer constituting the A block is benzyl methacrylate,
Among the monomers represented by the formula (2), the monomer constituting the B block is:
A monomer in which R ¹ is a hydrogen atom and R ² is a methyl group;
The ink set according to claim 4, wherein R ¹ is a C4 alkyl group and R ² is a monomer represented by a methyl group.   The ink set according to claim 1, wherein the water-insoluble colorant is a pigment.   The pigment is C.I. I. The ink set according to claim 6, wherein the ink set is a pigment selected from pigment and carbon black. The water-insoluble colorant contained in the yellow ink is C.I. I. Pigment yellow,
The water-insoluble colorant contained in the magenta ink is C.I. I. Pigment red,
The water-insoluble colorant contained in the cyan ink is C.I. I. Pigment blue, and the hue angle Hc ° is 240 ≦ Hc ° <270,
The ink set according to claim 1 or 3, wherein the water-insoluble colorant contained in the black ink is carbon black.   The ink set according to claim 1, further comprising one or more types of ink selected from blue ink, orange ink, and green ink. Each of the blue ink, the orange ink, and the green ink is an ink containing water, a water-insoluble colorant, propylene glycol, glycerin, and an alkylene oxide adduct of diglycerin. For the total mass of the ink,
Propylene glycol content is 5% by mass <propylene glycol <15% by mass,
The content of glycerin is 25% by mass <glycerin <35% by mass,
The ink set according to claim 9, wherein the content of the alkylene oxide adduct of diglycerin is 0% by mass <the alkylene oxide adduct of diglycerin <4% by mass.   The ink set according to claim 10, wherein each of the blue ink, the orange ink, and the green ink further contains a dispersant. The dispersant is an AB block polymer;
The monomer constituting the A block is a monomer selected from benzyl methacrylate and benzyl acrylate,
The ink set according to claim 11, wherein the monomers constituting the B block are two or more types of monomers represented by the following formula (2).

[In Formula (2), R ¹ represents a hydrogen atom or an alkyl group, and R ² represents a hydrogen atom or a methyl group. ]. The monomer constituting the A block is benzyl methacrylate,
Among the monomers represented by the formula (2), the monomer constituting the B block is:
A monomer in which R ¹ is a hydrogen atom and R ² is a methyl group;
The ink set according to claim 12, wherein R ¹ is a C4 alkyl group and R ² is a monomer represented by a methyl group. The water-insoluble colorant contained in the blue ink is C.I. I. Pigment blue, and the hue angle Hb ° is 270 ≦ Hb ° ≦ 330,
The water-insoluble colorant contained in the orange ink is C.I. I. Pigment orange,
The water-insoluble colorant contained in the green ink is C.I. I. The ink set according to any one of claims 9 to 11, which is Pigment Green.   The ink set according to claim 1, wherein the hue angle Hy ° of the yellow ink is 80 ≦ Hy ° ≦ 110.   The ink set according to any one of claims 1, 3 and 8, wherein a hue angle Hm ° of the magenta ink is either 355 ≦ Hm ° ≦ 360 or 0 ≦ Hm ° ≦ 15.   The ink set according to claim 9, wherein the hue angle Ho ° of the orange ink is 15 <Ho ° <80.   The ink set according to claim 9, wherein the hue angle Hg ° of the green ink is 120 ≦ Hg ° ≦ 200.   Inkjet recording in which recording is performed by causing one or more ink droplets selected from the ink set according to any one of claims 1 to 18 to be ejected according to a recording signal and adhered to a substrate. Method.   A substrate to which one or more types of ink selected from the ink set according to any one of claims 1 to 18 is attached.