JP6752173B2 - Ink composition - Google Patents

Description

The present invention relates to inks containing water, a water-insoluble colorant, specific amounts of propylene glycol, glycerin, and an alkylene adduct of diglycerin, respectively.

Inkjet recording has become widespread as a printing method for offices and homes as information digitization progresses. Further, in recent years, application to commercial printing and textile printing has been promoted. As the applications of inkjet recording have expanded, the colorants used for inkjet inks have changed from water-soluble dyes (eg, acid dyes, direct dyes, etc.) to water-insoluble colorants (for example, disperse dyes, and pigments) depending on the application. Etc.) have come to be used.

Generally, a recorded image using a water-soluble dye is said to have good image quality. On the other hand, recorded images using water-insoluble colorants are said to be excellent in various fastnesses to light, ozone, water and the like. Therefore, in the field of commercial printing, water-insoluble colorants are preferably used.
In the water-based ink containing a water-insoluble colorant, the colorant is dispersed in the ink as a solid. For this reason, it is said that it is difficult to better eject an ink containing a water-insoluble colorant from an inkjet printer as compared with an ink containing a water-soluble dye.
In addition, the base material used for commercial printing often does not have an ink receiving layer. For this reason, inks used for commercial printing often contain a resin for the purpose of improving the fixability of a colorant on a base material. Further, in the ink containing a water-insoluble colorant, the colorant is dispersed by a resin. For this reason, such inks generally have a high solid content in the ink, which is one of the major factors for deteriorating the ejection property.
In addition to this, inkjet printers used for commercial printing require inks with higher viscosities than office and home printers because they need to print at high speed. The high viscosity of the ink is also one of the factors that make it difficult to ensure good ejection properties.
One method for evaluating the ejection property is a method of photographing the state of the ejected droplets and visually confirming the state of the droplets. In this method, when the droplets are in a spherical shape, the ejection property is evaluated as good. On the other hand, when a tail is generated in the droplet and / or when the droplet is separated into a plurality of droplets and satellite is generated, the ejection property is evaluated as poor. Using this method, the state of the droplets ejected from the inkjet printer can be directly evaluated.
In commercial printing, intermittent recording (continuous recording-temporary suspension of recording for several tens of minutes to several hours-resumption of continuous recording) is performed for breaks and holidays. There are also many. If continuous recording is resumed after temporarily stopping recording, many inks have poor ejection properties. Therefore, in intermittent recording, there is a strong demand for an ink having good ejection properties even when continuous recording is restarted.

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

Japanese Unexamined Patent Publication No. 2015-193742 International Release 2014/084161 Gazette International Release 2015/152290 Gazette

An object of the present invention is an ink in which droplets ejected from an inkjet printer do not generate tails and satellites, and have good ejection properties even when continuous recording is resumed in intermittent recording at the same time as initial ejection. Is to provide.

As a result of diligent research to solve the above problems, the present inventors have contained water, a water-insoluble colorant, a specific amount of propylene glycol, glycerin, and an alkylene adduct of diglycerin, respectively. We have found that ink can solve the above-mentioned problems, and have completed the present invention. That is, the present invention relates to the following 1) to 16).

1)
An ink containing water, a water-insoluble colorant, propylene glycol, glycerin, and an alkylene adduct of diglycerin, with respect to the total mass of the ink.
The content of propylene glycol is 5% by mass <propylene glycol <15% by mass,
The content of glycerin is 25% by mass <glycerin <35% by mass,
An ink in which the content of the alkylene adduct adduct of diglycerin is 0% by mass <the alkylene adduct adduct of diglycerin <4% by mass.
2)
The ink according to 1) above, wherein the alkylene adduct adduct of diglycerin is a compound represented by the following formula (1).

[In the formula (1), AL independently represents C2-C4alkylene, and j, k, m, and n represent integers of 4 to 100 in total. ].
3)
The ink according to 1) above, which 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 according to 3) above, 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,
Of 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 according to 4) above, which is a monomer in which R ¹ is a C4 alkyl group and R ² is a methyl group.
6)
The ink according to 1) above, wherein the water-insoluble colorant is a pigment.
7)
The pigment is C.I. I. The ink according to 6) above, which is a pigment selected from pigment and carbon black.
8)
C. I. The pigment selected from the pigment is C.I. I. Pigment Yellow, C.I. I. Pigment Red, C.I. I. Pigment Blue, C.I. I. Pigment Violet, C.I. I. Pigment Orange and C.I. I. The ink according to 7) above, which is a pigment selected from Pigment Green.
9)
An inkjet recording method for recording by ejecting droplets of the ink according to any one of 1) to 8) above according to a recording signal and adhering them to a substrate.
10)
A base material to which the ink according to any one of 1) to 8) above is attached.
11)
A base material to which ink droplets are attached by the above-mentioned inkjet recording method of 9).

INDUSTRIAL APPLICABILITY According to the present invention, the droplets ejected from an inkjet printer are inks that do not generate tails and satellites, and an ink having good ejection properties can be provided in intermittent recording as well as initial ejection even when continuous recording is resumed. did it.

Unless otherwise specified, in this specification, "%" and "part" including examples and the like are described on a mass basis. Further, "CI" means a color index.
Further, the ink is a water-based ink containing water.

[Water-insoluble colorant]
In the present specification, the water-insoluble colorant is 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, still more preferably 100 mg / liter or less. Can be 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, metal chloride and the like. 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, channel black and the like. 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 Columbia Carbon Co., Ltd .; the Monarch series, Regal series, and Mogul series manufactured by Cabot Corporation; the Color Black series, Printex series, and Special Black series manufactured by Degussa Co., Ltd .; Mitsubishi Chemical Co., Ltd. Company-made MA series, MCF series, etc. can be mentioned.

As the white pigment, it is preferable to use a metal oxide. Examples of the metal oxide include zinc oxide, titanium oxide, zirconia oxide and the like, and titanium oxide is preferable. Examples of the type of titanium oxide include rutile type and anatase type. Titanium oxide can be used as it is as a powder. The surface can also be treated with silicon dioxide, aluminum oxide, zirconia oxide, zinc oxide, an organic compound having a hydroxy group, or the like. Of these, surface-treated titanium oxide is preferable.
Specific examples of titanium oxide include, for example, DUAWHITE series and TITONE series manufactured by Sakai Chemical Industry Co., Ltd .; Typake series manufactured by Ishihara Sangyo Co., Ltd .; TITANIX series manufactured by TAYCA Corporation; ST series manufactured by Titan Kogyo Co., Ltd. Can be mentioned.

Examples of the organic pigment 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, for example, 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; C.I. 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; C.I. I. Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 22, 25, 60, 66, 80; C.I. I. Pigment Violet 19, 23, 29, 37, 38, 50; C.I. I. Pigment Orange 13, 16, 34, 36, 43, 68, 69, 71, 73; C.I. I. Pigment Green 7, 36, 54; and C.I. I. Pigment Black 1, 7, etc. can be mentioned.

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 blacks are preferred; I. Pigment Yellow, C.I. I. Pigment Red, C.I. I. Pigment Blue, C.I. I. Pigment Violet, C.I. I. Pigment Orange and C.I. I. Pigment greens are more preferred.

The ink may contain one or more water-insoluble colorants. The purpose of using two or more kinds of colorants in combination is to improve the fluidity when the colorant is powdered, to adjust the hue, and the like.
The content of the colorant with respect to the total mass of the ink is usually 1% to 30%, preferably 1% to 15%, and 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%, and more preferably 7% ≤ propylene glycol ≤ 13% with respect to the total mass of the ink.

[Glycerin]
The ink contains glycerin. Its 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 adduct of diglycerin]
The ink contains an alkylene adduct adduct of diglycerin. Its content is usually 0% <diglycerin oxide alkylene adduct <4%, preferably 0.1% ≤ diglycerin oxide alkylene adduct ≤ 3%, more preferably 0% with respect to the total mass of the ink. 3% ≤ alkylene adduct adduct of diglycerin ≤ 3%, more preferably 0.5% ≤ alkylene adduct adduct of diglycerin ≤ 2.5%.
As the alkylene adduct adduct of diglycerin, the compound represented by the above formula (1) is preferable. The compound represented by the formula (1) is substantially a mixture of the compounds represented by the formula (1).
In formula (1), examples of C2-C4 alkylene in AL include straight chain, branched chain, and cyclic alkylene. Of these, straight chain or branched chain alkylene is preferable. The preferred range of carbon numbers is C2-C3, more preferably C3.
In formula (1), the sum of j, k, m and n is usually 4 to 100, preferably 4 to 90. The weight average molecular weight of these compounds is usually 300 to 5000, preferably 400 to 4500, more preferably 450 to 3000, still more preferably 700 to 2000, and in some cases preferably 750 to 1600, particularly preferably 750 to 1200. is there. The weight average molecular weight can be measured by GPC (gel permeation chromatography).
Specific examples thereof include SC-P400 (4/400), SC-P750 (9/750), SC-P1000 (14/1000), and 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 manufactured by NOF CORPORATION.
Among the above, in the "SC-P" and "DGP" series, AL in the formula (1) is a branched chain C3 alkylene, and in the "SC-E" series, AL is a linear C2 alkylene compound. Further, the parentheses of each specific example mean (average value of total 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-mentioned problems can be obtained.

[Dispersant]
The ink preferably further contains a dispersant. Examples of the dispersant include known dispersants. Examples thereof are styrene and its derivatives; vinylnaphthalene and its derivatives; aliphatic alcohol esters of α, β-ethylene unsaturated carboxylic acids; (meth) acrylic acid and its derivatives; mylenic acid and its derivatives; itaconic acid and At least two monomers (preferably, preferably) selected from the group of monomers consisting of derivatives thereof; carboxylic acid and derivatives thereof; vinyl acetate, vinyl alcohol, vinylpyrrolidone, (meth) acrylamide, derivatives thereof and the like. Examples thereof include copolymers composed of at least one of these (hydrophilic monomers).
In the present specification, "(meth) acrylic acid" is used as a meaning including "both acrylic acid and methacrylic acid". The same meaning is used for "(meth) acrylamide" and the like.
Examples of the type of copolymer include block copolymers, random copolymers, and graft copolymers, and / or salts thereof.
The dispersant can be synthesized or available as a commercial product. Specific examples of commercially available products include, for example, styrene-acrylic resins such as John Krill 62, 67, 68, 678, and 687 manufactured by Johnson Polymer Co., Ltd .; Movinyl S-100A (modified vinyl acetate manufactured by Hoechst Synthesis Co., Ltd.). Resin); Julimer AT-210 (polyacrylic acid ester copolymer manufactured by Nippon Pure Chemical Industries, 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 kinds of monomers represented by the above formula (2). -B block polymer is preferred.
Further, the monomer constituting the A block is benzyl methacrylate, and the monomer constituting the B block is a monomer represented by the formula (2) in which R ¹ is a hydrogen atom and R ² is a methyl group. And AB block polymer, which is two kinds of a monomer in which R ¹ is represented by a C4 alkyl group and R ² is represented by a methyl group, is more preferable.
Examples of such AB block polymers include dispersants disclosed in WO 2013/115071 Gazette.

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 1000 to 40,000, still more preferably 1500 to 30000, and particularly preferably 17,000 to 27,000. 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 mixed state with a colorant. It can also be used as a state in which the surface of the colorant is coated with a dispersant. Moreover, both of these can be used together.
When the dispersant is used, the ratio of the amount of the dispersant used 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. 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, its average particle size is usually 5 nm to 300 nm, preferably 50 nm to 200 nm, and more preferably 60 nm to 120 nm. By setting the average particle size in this range, the storage stability, ejection property, and print density (reflection density) of the dispersion can be improved. The average particle size can be measured using laser light scattering.

The ink is preferably made into an ink by preparing a dispersion liquid containing a colorant and a dispersant and then mixing the ink 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 and dispersion treatment is performed to obtain a liquid. By distilling off the organic solvent and a part of water under reduced pressure from the liquid thus obtained, a dispersion liquid containing a colorant can be obtained.
In the dispersion treatment, for example, the dispersant solution or emulsion and the colorant 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 disperse. When using a sand mill, beads having a particle size of about 0.01 mm to 1 mm can be used. The efficiency of the dispersion treatment can be adjusted by adjusting the bead filling rate, the dispersion time, the content of the colorant, and the like.
By filtering and / or centrifuging the dispersion liquid obtained as described above, the size of the particle size of the particles contained therein can be made uniform in a certain range.

The ink may further contain one or more water-soluble organic solvents as components other than the above, if necessary. Examples of such water-soluble organic solvents include C1-C4 monools such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, second butanol, third butanol; ethylene glycol, 1,3. -C2-C6 diols such as propanediol, 1,2- or 1,4-butanezyl, 1,3-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol; hexane C3-C6 triols such as -1,2,6-triol, trimethylolpropane; carboxylic acid amides such as N, N-dimethylformamide, N, N-dimethylacetamide; 2-pyrrolidone, N-methyl-2-pyrrolidone, Nitrogen-containing heterocyclic compounds such as 1,3-dimethylimidazolidine-2-one and 1,3-dimethylhexahydropyrimido-2-one; acetone, methyl ethyl ketone, 2-methyl-2-hydroxypentane-4-one and the like. Ketone or keto alcohol; chain or cyclic ethers such as 1,2-dimethoxyethane, tetrahydrofuran, dioxane; di or tri C2-C3 alkylene glycols or thio such as diethylene glycol, triethylene glycol, dipropylene glycol, thiodiglycol. Glycol; Poly C2-C3 having a repeating unit of 4 or more and a molecular weight of about 20000 or less, such as tetraethylene glycol, polyethylene glycol (preferably those having a molecular weight of 2000 or less such as 400, 800, 1540, etc.), polypropylene glycol, etc. Alkylene glycol (preferably liquid); polyglyceryl ethers such as diglycerin, triglycerin, polyglycerin; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monomethyl ether, tri Polyhydric alcohol alkyl ethers such as ethylene glycol monoethyl ethers and triethylene glycol monobutyl ethers (preferably C1-C6 alkyl ethers); cyclic esters or carbonates such as γ-butyrolactone and ethylene carbonate; dimethylsulfoxide; acetic acid and the like. Be done.
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%, based on the total mass of the water-soluble organic solvents. , More preferably 0% to 30%, further preferably 0% to 20%, and particularly preferably about 0% to 10%. Within such a range of total content, it is possible to maintain a state in which the ink ejection property is good.

The ink may further contain one or more kinds of components other than the above as an ink preparation agent. Examples of the ink preparation agent include antiseptic / antifungal agents, pH adjusters, chelating reagents, rust preventives, 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 fungicide 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-based, organic nitrogen-sulfur-based, organic halogen-based, haloarylsulfone-based, iodopropagil-based, haloalkylthio-based, nitrile-based, pyridine-based, 8-oxyquinolin-based, and benzothiazole-based. Isothiazolin-based, dithiol-based, pyridine oxide-based, nitropropane-based, organic tin-based, phenol-based, tetraammonium salt-based, triazine-based, thiazine-based, anilide-based, adamantan-based, dithiocarbamate-based, brominated indanone-based, benzyl brom Examples thereof include acetate-based and inorganic salt-based compounds.
Examples of the organic halogen-based compound include sodium pentachlorophenol. Examples of the pyridine oxide compound include 2-pyridinethiol-1-oxide sodium. Examples of the isothiazolin-based compound include 1,2-benzisothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, and 5, −Chloro-2-methyl-4-isothiazolin-3-onemagnesium chloride, 5-chloro-2-methyl-4-isothiazolin-3-onecalcium chloride, 2-methyl-4-isothiazolin-3-onecalcium chloride, etc. Can be mentioned.
Examples of other antiseptic and fungicides 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 the pH of the ink can be controlled in 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.
Of these, organic bases are preferred, and alkanolamine compounds are more preferred.
Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, potassium hydroxide and the like.
Examples of the hydroxide of the alkaline earth metal include beryllium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide and the like.
Among the inorganic bases, alkali metal hydroxides and ammonia are preferable. Of these, lithium hydroxide, sodium hydroxide, and ammonia are preferred.
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 mono, di, or tri-C1- such as monoethanolamine, diethanolamine, triethanolamine, monopropanolamine, dipropanolamine, tripropanolamine, methylethanolamine, dimethylethanolamine, and N-methyldiethanolamine. Examples include C3 alkanolamine compounds. Among these, tertiary amines are preferable, and triethanolamine is particularly preferable.
Other examples include, for example, carbonates of alkali metals such as lithium carbonate, sodium carbonate, sodium hydrogencarbonate, potassium carbonate; alkali metal salts of organic acids such as sodium silicate and potassium acetate; phosphorus such as disodium phosphate. Phosphate; etc.

Examples of the chelating reagent include disodium ethylenediaminetetraacetate, sodium nitrilotriacetic acid, sodium hydroxyethylethylenediamine triacetate, sodium diethylenetriamine pentaacetate, and sodium uracil diacetate.

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

Examples of the water-soluble ultraviolet absorber include sulfonated benzophenone compounds, benzotriazol 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-based fading inhibitors can be used. Examples of the organic anti-fading agent include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indans, chromans, alkoxyanilines, heterocyclics and the like.

Examples of the surfactant include known surfactants such as anion, cation, nonion, amphoteric, silicone-based, and fluorine-based. Of these, nonionic surfactants are preferred.
As anionic surfactants, alkyl sulfocarboxylic acid salts, α-olefin sulfonates, polyoxyethylene alkyl ether acetates, polyoxyethylene alkyl ether sulfates, N-acylamino acids or salts thereof, N-acylmethyl taurine salts, etc. Alkyl Sulfate Polyoxyalkyl Ether Sulfate, Alkyl Sulfate Polyoxyethylene Alkether Sulfate, Loginate Soap, Himasi Oil Sulfate, Lauryl Alcohol Sulfate, Alkylphenol Phosphate, Alkyl Phosphate, Examples thereof include alkylaryl sulfonate, diethyl sulfo sulfonate, diethyl hexyl sulfo sulfonate, dioctyl sulfo sulfonate and the like.

Examples of the cationic surfactant include 2-vinylpyridine derivatives and poly4-vinylpyridine derivatives.

Nonionic surfactants include polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether and other ethers; Esters such as oxyethylene oleic acid ester, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, polyoxyethylene stearate; 2 , 4,7,9-Tetramethyl-5-decine-4,7-diol, 3,6-dimethyl-4-octin-3,6-diol, 3,5-dimethyl-1-hexin-3-ol, Surfinol 104, 104PG50, 82, 420, 440, 465, 485, Orphine STG and other acetylene glycol (alcohol) -based products manufactured by Nisshin Kagaku Co., Ltd., and their C2-C4 alkyleneoxy adducts; For example, Tergitol 15-S-7) manufactured by SIGMA-ALDRICH, etc. can be mentioned. Of these, the acetylene glycol type is preferable, and the Surfinol series is more preferable.

Examples of amphoteric surfactants include betaine lauryldimethylaminoacetate, 2-alkyl-N-carboxymethyl-N-hydroxyethyl imidazolinium betaine, betaine palm oil fatty acid amide propyldimethylaminoacetate, polyoctylpolyaminoethylglycine, and imidazoline derivatives. Can be mentioned.

Examples of the silicone-based surfactant include polyether-modified siloxane and polyether-modified polydimethylsiloxane. As an example, Dynol 960, 980 manufactured by Air Products & Chemicals Co., Ltd .; Silface SAG001, SAG002, SAG003, SAG005, SAG503A, SAG008, SAG090, SAG010 manufactured by Nisshin Chemical Co., Ltd .; and BYK-345 manufactured by Big Chemie Co., Ltd. 347, 348, 349, 3455 and the like can be mentioned.

Examples of the fluorine-based surfactant 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. Examples thereof include a polyoxyalkylene ether polymer compound contained in. As the fluorine-based surfactant, various types of products can be easily purchased from, for example, DuPont, Omniova, DIC Corporation, Big Chemie, and the like.

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, a surfactant, or the like.

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

The inkjet recording method is a method of recording by ejecting droplets of the ink in response to a recording signal and adhering them to a base material. The inkjet recording method is not particularly limited, and various known methods can be used. Examples of the inkjet recording method include a charge control method, a drop-on-demand method (also referred to as a pressure pulse method), an acoustic inkjet method, and a thermal inkjet method. Of these, the drop-on-demand method is preferable.

The base material is not particularly limited as long as it is a substance colored by the ink. Examples thereof include fibers; paper having an ink receiving layer; and an ink poorly absorbing or non-absorbing base material having no ink receiving layer. Examples of the poorly absorbable ink base material 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 base material include vinyl chloride sheet, polymer sheet, glass, rubber and the like. Among these, fibers, paper having an ink receiving layer, and a poorly absorbent ink-absorbing base material having no ink receiving layer are preferable.

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

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

In the above-mentioned inkjet recording method, full-color recording can be performed by using, for example, four color ink sets of yellow, red, blue, and black. Further, by using inks of each color such as violet, orange, and green, it is possible to use the inks as an ink set of four or more colors and obtain a higher-definition recorded image.

For all the above items, the combination of preferable ones is more preferable, and the combination of more preferable ones is further preferable. The same applies to a combination of a preferable one and a more preferable one.

The ink is an ink in which droplets ejected from an inkjet printer do not form tails and satellites. Further, it is an ink having a high viscosity, which is suitable for an inkjet printer for commercial printing.
The ink is well filled in the inkjet head. In addition, stable ejection can be achieved without bending or blurring during inkjet recording.
The ink does not clog the nozzle of the print head in both continuous recording for a long time and intermittent recording.
The ink has good storage stability during storage, and even if the ink loses water or the like in the ink and the ink dries to form a solid substance, the solid substance can be redispersed by replenishing the ink. Very good.
With the ink, a recorded image with no bleeding and high color development can be obtained.
With the ink, recorded images having various fastnesses, such as light resistance and water resistance, can be obtained.

Hereinafter, the present invention will be specifically described with reference to Examples. However, the present invention is not limited to the examples.
The "water" used in the examples is ion-exchanged water.
In the examples, when it was necessary to measure the content of the colorant in the dispersion liquid, it was determined by the dry weight method using MS-70 manufactured by A & D Co., Ltd. The colorant content is a converted value from the total solid content 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, and the monomer constituting the B block is a monomer represented by the formula (2), in which R ¹ is a hydrogen atom and R ² is a methyl group. There are two types, a monomer represented by, and a monomer in which R ¹ is represented by an n-butyl group as a C4 alkyl group and R ² is represented by 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. A solution prepared by dissolving 0.47 parts of sodium hydroxide in water (51.45 parts) was added to this solution, and the mixture was stirred for 1 hour to obtain an emulsion. In the obtained liquid, C.I. I. Pigment Yellow 155 (21 parts) was added, and the mixture was dispersed in a sand grinder at 1500 rpm 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 (glass filter paper manufactured by Advantech Co., Ltd. (two layers were stacked so that GA100 was on the top and GC50 was on the bottom) to obtain a filtrate. 2-Butanone and a part of water in the obtained filtrate were distilled off under reduced pressure with an evaporator to obtain a dispersion having a colorant content of 12%. This 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 in Preparation Example 2 except that each component used in Preparation Example 2 was replaced with the component and the amount used in Table 1 below. .. The numerical value of each component is "part", and the amount of water added was adjusted so that the total content of the colorant in each dispersion was 12%.

The abbreviations and the like in Table 1 below represent the following meanings.
PY155 = C.I. I. Pigment Yellow 155.
PR122 = C.I. I. Pigment Red 122 (manufactured by Clariant, INCJET MAGENTA E-02).
PR150 = C.I. I. Pigment Red 150.
PB15: 4 = C.I. I. Pigment Blue 15: 4.
CB = carbon black.
PB15: 6 = C.I. I. Pigment Blue 15: 6.
PO43 = C.I. I. Pigment Orange 43.
PG36 = C.I. 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 to 9 above.
DP1 to DP8 = Dispersions 1 to 8 prepared in Preparation Examples 2 to 9 above.

[Examples 1 to 21]: Preparation of ink.
Each component shown in Tables 2 to 4 below was mixed, sufficiently stirred, and then filtered through a 5 μm membrane filter to obtain the inks of Examples 1 to 21 used in the evaluation test. The numerical value of each component is "parts", and the amount of water added was adjusted so that the total amount was 100 parts.

[Comparative Examples 1 to 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 shown in Table 5 below was used.

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

[Drop condition test]
Using an industrial inkjet head evaluation device (expandable coating device EV2500, manufactured by Ricoh Co., Ltd.), ink droplets of Examples and Comparative Examples were ejected, and then photographs of the droplets were taken every 4 microseconds. The droplets were discharged at a head built-in heater set to 28 ° C., a head drive voltage of 14.0 V, and a frequency of 2 kHz. The state of the droplets when the ink droplets flew 1 mm was confirmed by 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: No tail or satellite is found on the ink droplets.
B: Either the tail or the satellite is recognized in the ink droplet.
C: Both the tail and the satellite are observed in the ink droplet.
D: The ink droplets are ejected in a scattered state.

[Initial discharge test]
Using the above-mentioned industrial inkjet head evaluation device, a nozzle check pattern was inkjet-recorded on the following substrate. Recording was performed with the head built-in heater set to 28 ° C. and a head drive voltage of 14.0 V, 10 kHz. 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 <gloss>, model number: KA4100PSKR was arbitrarily used. There was no difference in the state of the nozzle check patterns recorded on these substrates.
[Evaluation criteria]
A: No "blurring" is observed in the recorded image.
B: When the recorded image is observed in detail, a slight "blurring" is observed.
C: "Blur" is observed in the recorded image.
D: The recorded image is clearly "faint".

[Intermittent recording test]
After the nozzle check pattern was inkjet-recorded on the substrate in the same manner as in the above-mentioned [Initial discharge test], the recording was stopped. After leaving the industrial inkjet head evaluation device as it is for 30 minutes, the nozzle check pattern is again inkjet-recorded on the base material, the state of the recorded image is visually confirmed, and the evaluation in the following four stages A to D is performed. Evaluated by criteria.
[Evaluation criteria]
A: No "blurring" is observed in the recorded image.
B: When the recorded image is observed in detail, a slight "blurring" is observed.
C: "Blur" is observed in the recorded image.
D: The recorded image is clearly "faint".

The abbreviations and the like in Tables 6 to 8 below 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 = The above-mentioned [droplet state test].
PG = content of propylene glycol with respect to the total mass of the ink.
GL = content of glycerin relative to total mass of ink.
DGA = content of alkylene oxide adduct of diglycerin relative to total mass of ink.

As is clear from the results in Tables 6 to 8, all the evaluations 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 discharge and intermittent recording of Comparative Examples 1 and 3 were "A" in the above evaluation criteria. However, in those recorded images, the ink was scattered, and the portion that should be a white background was also colored. That is, the inks of Comparative Examples 1 and 3 could not inkjet record a normal nozzle check pattern in both the initial ejection and the intermittent recording.

The ink of the present invention is an ink that does not generate tails and satellites, and is extremely useful as an inkjet ink because it has good ejection properties in intermittent recording as well as in initial ejection even when continuous recording is resumed.

Claims (11)

An ink containing water, a water-insoluble colorant, propylene glycol, glycerin, and an alkylene adduct of diglycerin, with respect to the total mass of the ink.
The content of propylene glycol is 5% by mass <propylene glycol <15% by mass,
The content of glycerin is 25% by mass <glycerin <35% by mass,
An ink in which the content of the alkylene adduct adduct of diglycerin is 0% by mass <the alkylene adduct adduct of diglycerin <4% by mass. The ink according to claim 1, wherein the alkylene adduct adduct of diglycerin is a compound represented by the following formula (1).

[In the formula (1), AL independently represents C2-C4alkylene, and j, k, m, and n represent integers of 4 to 100 in total. ]. The ink according to claim 1, further containing 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 according to claim 3, wherein the monomer constituting the B block is two or more kinds 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,
Of 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 according to claim 4, wherein R ¹ is a monomer represented by a C4 alkyl group and R ² is a monomer represented by a methyl group. The ink according to claim 1, wherein the water-insoluble colorant is a pigment. The pigment is C.I. I. The ink according to claim 6, which is a pigment selected from pigment and carbon black. C. I. The pigment selected from the pigment is C.I. I. Pigment Yellow, C.I. I. Pigment Red, C.I. I. Pigment Blue, C.I. I. Pigment Violet, C.I. I. Pigment Orange and C.I. I. The ink according to claim 7, which is a pigment selected from Pigment Green. An inkjet recording method for recording by ejecting a droplet of the ink according to any one of claims 1 to 8 according to a recording signal and adhering it to a base material. A base material to which the ink according to any one of claims 1 to 8 is attached. A base material to which ink droplets are attached by the inkjet recording method of claim 9.