JP2017218542A - Ink, inkjet recording method and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide ink which is excellent in transferability, initial ejectability and ejection stability and also has storage stability, an inkjet recording method using the ink and a recording medium to which the ink is adhered.SOLUTION: The ink is provided that contains a water-insoluble colorant, an alkali-soluble resin, a polymer and water, where the polymer is a polymer composed of three kinds of methacrylic acid derivatives and one acrylic acid derivative, a weight average molecular weight of the alkali soluble resin is 1,500-10,000 and a content (AW) of the alkali-soluble resin and a content (BW) of the polymer with respect to the total mass of the ink satisfy in terms of mass, both of expression (1): AW/BW=0.4 or more and less than 1.5 and expression (2): AW+BW=2.4-4.5 mass%.SELECTED DRAWING: None

Description

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

  As various types of information have been digitized, inkjet recording methods have become widespread for recording (printing) applications in offices and homes. In recent years, inkjet recording applications have been expanded to industrial applications such as variable information, textiles, advertising, and signage.

  In industrial applications, there is a strong demand for ink jet recording at high speed. Ink jet recording at high speeds is extremely important for ink drying and abrasion resistance. If the drying property and abrasion resistance of the ink are low, a plurality of recorded materials are stacked before the recorded ink is dried. As a result, an image recorded with undried ink comes into contact with another recorded matter, and both the image and the other recorded matter are contaminated. Preventing such a situation is one major issue.

In industrial applications, it is required that ink jet recording can be performed on various types of recording media. One example is a crimped paper. The pressure-bonded paper is one of recording media used for recording variable information such as highly confidential personal information. Among them, a pressure-sensitive adhesive paper pretreated with a pressure-sensitive adhesive and processed into a size corresponding to two postcards is widely used in Japan. That is, after the variable information is ink-jet recorded on one side of the pressure-bonding paper, the other half-side is overlapped and pressure-bonded to be mailed as a postcard. For this reason, pressure-sensitive paper is widely used for communicating various variable information to the correct owner of the information.
As described above, since the pressure-sensitive adhesive paper for postcards is pressure-bonded with the blank information surface superimposed on the variable information recording surface, the ink on the recording surface must not be transferred to the blank paper surface when the two surfaces are peeled off. It is.
In addition, since the pressure-sensitive adhesive paper performs inkjet recording on a paper surface pretreated with a pressure-sensitive adhesive, it is required to record with high image quality without causing bleeding or the like even when it comes into contact with the adhesive. An example of recording with high image quality is barcode recording.

In addition, in ink jet recording for industrial use, good ejection properties are also strongly required. In particular, initial ejection properties and ejection stability when continuously ejecting are problems.
Initial ejection refers to the ability to perform good ejection without missing pins when the inkjet printer is started from a stopped state. Ink with poor initial ejection requires cleaning of the recording head.
In addition, although the initial ejection is good, there are some inks that begin to lack pins when ejected continuously. Since the recorded matter in which the pin is missing becomes a defective product, the ink having poor ejection stability when continuously ejecting causes a serious problem more than the ink having poor initial ejection.
Furthermore, it goes without saying that good storage stability is required for the ink.

  Patent Documents 1 and 2 disclose an ink composition containing a styrene-acrylic resin and a polymer.

International Publication No. 2015/152291 Gazette International Publication No. 2015/147192 No. Gazette

  An object of the present invention is to provide an ink having excellent transferability, initial ejection properties, ejection stability, and excellent storage stability, an ink jet recording method using the ink, and a recording medium having the ink attached thereto.

  The inventor of the present invention has intensively studied to solve the above problems. As a result, the ink contains a water-insoluble colorant, a specific alkali-soluble resin, a specific polymer, and water, and the content of the alkali-soluble resin and the polymer satisfies the following formulas (1) and (2). The inventors have found that the above problems can be solved. That is, the present invention relates to the following 1) to 11).

1)
An ink containing a water-insoluble colorant, an alkali-soluble resin, a polymer, and water, wherein the polymer is a polymer composed of three types of methacrylic acid derivatives and one type of acrylic acid derivative, and the alkali-soluble The weight average molecular weight of the resin is 1500 to 10,000, and the content (AW) of the alkali-soluble resin and the content (BW) of the polymer with respect to the total mass of the ink are expressed by the following formulas (1) and ( Ink satisfying both of 2).
Formula (1): AW / BW = greater than 0.4 and less than 1.5.
Formula (2): AW + BW = 2.4 mass%-4.5 mass%.
2)
The ink according to 1), wherein the alkali-soluble resin is a water-insoluble colorant dispersant.
3)
The ink according to 1) above, wherein the content of the polymer with respect to the total mass of the ink is 1 to 2.5% by mass.
4)
The ink according to 1), wherein the alkali-soluble resin is a styrene-acrylic resin.
5)
The ink according to 1), wherein the polymer is a polymer composed of methacrylic acid, two types of alkyl methacrylate, and alkyl acrylate.
6)
The ink according to any one of 1), 3), and 5), wherein the polymer is a polymer composed of methacrylic acid, two types of C1-C3 alkyl methacrylate, and C6-C10 alkyl acrylate.
7)
The ink according to any one of 1) to 6), further comprising a water-soluble organic solvent.
8)
An ink jet recording method in which recording is performed by ejecting the ink droplet according to any one of 1) to 7) according to a recording signal and attaching the ink droplet to a recording medium.
9)
The inkjet recording method according to 8), wherein the recording medium is a pressure-bonded paper.
10)
A recording medium to which the ink according to any one of 1) to 7) is attached.
11)
An inkjet printer comprising a container containing the ink according to any one of 1) to 7).

  According to the present invention, it is possible to provide an ink having excellent transferability, initial ejection property, ejection stability and excellent storage stability, an ink jet recording method using the ink, and a recording medium having the ink attached thereto.

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

[Water-insoluble colorant]
The colorant contained in the ink is not particularly limited, and any water-soluble colorant can be used. A water-insoluble colorant can be used in combination as necessary.
In the present specification, “water-insoluble” means that the solubility of the colorant in water at 25 ° C. is usually 3 g / liter or less, preferably 2 g / liter or less, more preferably 1 g / liter or less. The lower limit includes 0 g / liter.
Examples of the water-insoluble colorant include pigments, disperse dyes, and solvent dyes. Typical examples of these colorants are C.I. I. Pigment, C.I. I. Disperse and C.I. I. Colorants selected from Solvent are mentioned.

  As a colorant other than those described above, a resin containing a colorant in which the above-described colorant is contained in a water-insoluble resin can also be cited as a water-insoluble colorant. When such a colored resin is used as a colorant, a water-soluble colorant can be contained in the water-insoluble resin. Examples of the water-soluble colorant at this time include direct dyes, acid dyes, food dyes, basic dyes, reactive dyes, vat dyes, and soluble vat dyes. Representative examples of these dyes are C.I. I. Direct, C.I. I. Acid, C.I. I. Food, C.I. I. Basic, C.I. I. Reactive, C.I. I. Vat, C.I. I. Mention may be made of dyes selected from Solubilized Vat.

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

  Examples of carbon black include thermal black, acetylene black, oil furnace black, gas furnace black, lamp black, gas black, and channel black. Various types of carbon black can be easily obtained as commercial products. Examples include the Raven series from Columbian Carbon, the Monarch series and Regal series from Cabot, the Color Black series, Printex series, Special Black series from Mitsubishi Chemical Corporation, and the MA series and MCF series from Mitsubishi Chemical Corporation. Can be mentioned.

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

  Specific examples of the organic pigment include C.I. I. Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 24, 55, 73, 74, 75, 83, 93, 94, 95, 97, 98, 108, 114, 128, 129, 138, 139, 150, 151, 154, 180, 185, 193, 199, 202, etc .; I. Pigment Red 5, 7, 12, 48, 48: 1, 57, 88, 112, 122, 123, 146, 149, 166, 168, 177, 178, 179, 184, 185, 202, 206, 207, 254, Red such as 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, etc .; I. Pigment Violet 19, 23, 29, 37, 38, 50, etc. violet; C.I. I. Pigment Orange 13, 16, 68, 69, 71, 73, etc. orange; C.I. I. Pigment Green 7, 36, 54, etc. green; C.I. I. Pigment Black 1 and other black pigments.

  Examples of extender pigments include silica, calcium carbonate, talc, clay, barium sulfate, and white carbon. These extender pigments are often used in combination with an inorganic pigment or an organic pigment for the purpose of improving the fluidity of the powder.

  In addition, a self-dispersing pigment imparted with a self-dispersibility by chemical treatment on the surface of the pigment particles can also be used.

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

  The content of the colorant in the total mass of the ink is usually 1 to 30%, preferably 1 to 15%, more preferably 2 to 10%.

[Alkali-soluble resin]
The alkali-soluble resin is preferably a water-insoluble colorant dispersant, and more preferably a styrene-acrylic resin.

As the styrene-acrylic copolymer, a copolymer of a compound containing an aromatic hydrocarbon group and (meth) acrylic acid (ester); a compound containing an aromatic hydrocarbon group, and (meth) acrylic acid (ester) , And (anhydrous) maleic anhydride copolymer;
Preferred examples of the copolymer of a compound containing an aromatic hydrocarbon group and (meth) acrylic acid (ester) include a copolymer having a hydrophilic part and a hydrophobic part in the molecule.
The term “(meth) acrylic acid (ester)” is used herein to mean acrylic acid, methacrylic acid, acrylic acid ester, and methacrylic acid ester, and “(anhydrous) maleic acid” is anhydrous. The meanings including maleic acid and maleic acid are used respectively. For copolymerization with a compound containing an aromatic hydrocarbon group, a single compound can be used, or a plurality of these compounds can be used in combination. In addition, when copolymerization is performed, maleic anhydride is added to form a copolymer of an aromatic hydrocarbon group-containing compound, (meth) acrylic acid (ester), and (anhydrous) maleic acid. .
Specific examples of these copolymers include (α-methyl) styrene-acrylic acid copolymer, (α-methyl) styrene-acrylic acid-acrylic acid ester copolymer, (α-methyl) styrene-methacrylic acid. Copolymer, (α-methyl) styrene-methacrylic acid-acrylic acid ester copolymer, (α-methyl) styrene- (anhydrous) maleic acid copolymer, acrylic acid ester- (anhydrous) maleic acid copolymer, (Α-methyl) styrene-acrylic acid ester- (anhydrous) maleic acid maleic acid copolymer, acrylic acid ester-allylsulfonic acid ester copolymer, acrylic acid ester-styrenesulfonic acid copolymer, (α-methyl) Styrene-methacrylsulfonic acid copolymer, polyester-acrylic acid copolymer, polyester-acrylic acid-acrylic ester Polymer, polyester - methacrylic acid copolymer, polyester - methacrylic acid - acrylic acid copolymer ester; and the like. Among these, the compound containing an aromatic hydrocarbon group is preferably styrene.
In the present specification, (α-methyl) styrene is used to mean α-methylstyrene and styrene.

  The weight average molecular weight of the alkali-soluble resin is usually 1,500 to 10,000, preferably 1,700 to 10,000, more preferably 3,000 to 10,000, and further preferably 5,000 to 10,000. More preferably, it is 8,000-10,000, Most preferably, it is 8,000-9,000. The weight average molecular weight can be measured by GPC (gel permeation chromatograph) method.

The acid value of the alkali-soluble resin is usually 150 to 250 mgKOH / g, preferably 160 to 250 mgKOH / g. The acid value of the resin represents the number of mg of KOH required to neutralize 1 g of the resin, and is measured according to JIS-K3054.
The dispersant may be synthesized by a known method or purchased as a commercial product. Among the commercially available products, specific examples of the styrene-acrylic copolymer include Jonkrill 678, 682, and 683 manufactured by BASF. Among these, 678 (weight average molecular weight = 8,500, acid value = 215), 682 (weight average molecular weight = 1,700, acid value = 238), 683 (weight average molecular weight = 8,000, acid value = 160) Etc.) are preferred.

[polymer]
The polymer is a polymer composed of three types of methacrylic acid derivatives and one type of acrylic acid derivative. Polymers composed of methacrylic acid, two types of alkyl methacrylate, and alkyl acrylate are preferred. A polymer composed of methacrylic acid, two types of C1-C3 alkyl methacrylate, and C6-C10 alkyl acrylate is more preferable. Examples of the polymer include polymers obtained by block copolymerization, random copolymerization, and graft copolymerization.

[Methacrylic acid derivative]
As the methacrylic acid derivative, alkyl methacrylate and methacrylic acid are preferable.
As the alkyl methacrylate, the alkyl moiety is usually C1-C18, preferably C1-C12, more preferably C1-C8, and examples thereof include saturated or unsaturated alkyl methacrylate.
Specific examples of the saturated alkyl methacrylate include linear alkyl methacrylate such as methyl methacrylate, butyl methacrylate and octyl methacrylate; branched alkyl methacrylate such as isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, isohexyl methacrylate and 2-ethylhexyl methacrylate; And cyclic alkyl methacrylates such as cyclopropyl methacrylate, cyclobutyl methacrylate, cyclopentyl methacrylate, and cyclohexyl methacrylate.
As the unsaturated alkyl methacrylate, an unsaturated C1-C4 alkyl methacrylate is more preferable. Specific examples thereof include vinyl methacrylate, allyl methacrylate, propenyl methacrylate, butenyl methacrylate, butadienyl methacrylate and the like.

[Acrylic acid derivative]
Examples of the acrylic acid derivative include compounds in which “methacrylic acid” in the [methacrylic acid derivative] is read as “acrylic acid” and “methacrylate” is read as “acrylate”.

As the two types of alkyl methacrylate, monomers selected from each of linear alkyl methacrylate and unsaturated alkyl methacrylate are preferable.
Of the foregoing, the straight chain alkyl methacrylate is more preferably a straight chain C1-C3 alkyl methacrylate, and more preferably methyl methacrylate.
Of the above, the unsaturated alkyl methacrylate is more preferably an unsaturated C1-C4 alkyl methacrylate, and more preferably allyl methacrylate.
The alkyl acrylate constituting the polymer is preferably a branched alkyl acrylate, more preferably a branched C1-C8 alkyl acrylate, and even more preferably 2-ethylhexyl acrylate.

  The polymer can be obtained, for example, by a synthesis method disclosed in International Publication No. 2015/147192 Gazette. The polymer can also be used as an emulsion.

The monomer composition of the polymer is summarized in Table 1 below as “normal”, “preferred”, and “more preferable” configurations. In the range of each monomer shown in Table 1 below, the total amount of monomers can be 100 parts. The abbreviations in Table 1 below have the following meanings.
MA: Methacrylic acid.
ScAM: linear alkyl methacrylate.
BcAA: branched chain alkyl acrylate.
UsAM: unsaturated alkyl methacrylate.

The average particle diameter (D50) of the polymer is usually about 10 nm to 1 μm, preferably about 30 nm to 500 nm.
The glass transition point (TG) of the polymer is usually -10 ° C to 20 ° C, preferably -5 ° C to 15 ° C.
The acid value of the polymer is usually 0 to 25 KOH mg / g, preferably 5 to 15 KOH mg / g.
The insolubility of the polymer in tetrahydrofuran is usually 80 to 100%, preferably 100%.

When the alkaline resin and the polymer are used, a neutralizing agent that neutralizes the acid value can be used. Examples of the neutralizing agent include alkali metal hydroxides, alkaline earth metal hydroxides, and amine compounds. 1-5 types of neutralizers are used normally, Preferably 1-4 types, More preferably, about 1-3 types can be used arbitrarily.
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.
Examples of the amine compound include ammonia (including ammonia water), an alkylamine compound, and an alkylamine compound having a hydroxy group as a substituent.
Examples of the alkylamine compound include amine compounds having 1 to 3 C1-C6 alkyl groups. Specific examples thereof include monomethylamine, dimethylamine, trimethylamine, monoethylamine, dimethylamine and trimethylamine.
Examples of the amine compound having a hydroxy group as a substituent include an amine compound in which at least one of the alkyl groups of the alkylamine compound has a hydroxy group as a substituent. Specific examples thereof include monoethanolamine, diethanolamine, triethanolamine, monopropanolamine, dipropanolamine, tripropanolamine, methylethanolamine, dimethylethanolamine and N-methyldiethanolamine.

  The use amount of the neutralizing agent can be represented by the degree of neutralization. When the acid value of the polymer is neutralized with a theoretical equivalent, the degree of neutralization is 100%. The neutralizing agent can be used in excess of the theoretical amount. The degree of neutralization of the polymer is usually 50 to 200%, preferably 80 to 150%, more preferably 100 to 120%.

The ink satisfies both the following formulas (1) and (2) on a mass basis when the content of the alkali-soluble resin with respect to the total mass is “AW” and the content of the polymer is “BW”. The effects obtained by the present invention can be achieved. After calculating AW / BW and AW + BW, respectively, the values of Equation (1) and Equation (2) are calculated by rounding off the second decimal place of the calculated numerical value to determine whether the range of each equation is satisfied. judge.
In the formula (1), the value of AW / BW is usually more than 0.4 and less than 1.5, preferably more than 0.5 and less than 1.5, more preferably 0.6 to 1.3.
In the formula (2), the value of AW + BW is usually 2.4% to 4.5%, preferably 2.5% to 4.3%, more preferably 2.8% to 4.1%.

There are various known methods for preparing ink. As one of the preparation methods, there can be mentioned a method in which a dispersant is added only when a colorant and a dispersant are added to prepare a dispersion, and an ink preparation is added to the obtained dispersion to prepare an ink.
As another method, a method of preparing an ink by adding a colorant and a dispersant and then further adding a dispersant and an ink preparation agent may be used.
The ink can be prepared, for example, by such a preparation method.

  The ink may contain an ink preparation agent as a component other than the above. Examples of the ink preparation agent include water-soluble organic solvents, preservatives, antifungal agents, pH adjusters, chelating reagents, rust preventives, water-soluble ultraviolet absorbers, antioxidants, surfactants, and antifoaming agents. .

Examples of the water-soluble organic solvent include C1-C6 alkanol having one hydroxy group such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol or tert-butanol; N, N-dimethylformamide or Amides such as N, N-dimethylacetamide; Lactams such as 2-pyrrolidone, N-methyl-2-pyrrolidone or N-methylpyrrolidin-2-one; 1,3-dimethylimidazolidin-2-one or 1,3 -Cyclic urea such as dimethylhexahydropyrimido-2-one; ketone or ketoalcohol such as acetone, 2-methyl-2-hydroxypentan-4-one, ethylene carbonate; cyclic ether such as tetrahydrofuran or dioxane; ethylene glycol , Diethylene glycol, , 2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,4-butylene glycol, 1,2-hexylene glycol, 1,6-hexylene glycol, diethylene glycol, triethylene glycol, tetra Mono-, oligo- or polyalkylene glycols or thioglycols having C2-C6 alkylene units, such as ethylene glycol, dipropylene glycol, polyethylene glycol or polypropylene glycol having a molecular weight of 400 or more, thiodiglycol or dithiodiglycol; glycerin, diglycerin , Polyols (triols) such as hexane-1,2,6-triol, trimethylolpropane; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether Diethylene glycol monoethyl ether, diethylene glycol monobutyl ether (butyl carbitol), triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, ethylene glycol monoallyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monomethyl ether, propylene glycol monopropyl ether, tri C1-C4 alkyl ethers of polyhydric alcohols such as ethylene glycol monobutyl ether; γ-butyrolactone or dimethyl sulfoxide;
By using a water-soluble organic solvent, for example, the physical properties of the ink such as drying properties can be controlled. For this reason, the ink preferably contains a water-soluble organic solvent.

  Examples of preservatives include, for example, organic sulfur, organic nitrogen sulfur, organic halogen, haloaryl sulfone, iodopropargyl, haloalkylthio, nitrile, pyridine, 8-oxyquinoline, benzothiazole, isothiazoline, dithiol, pyridine oxide, nitropropane. , Organic tin, phenol, quaternary ammonium salt, triazine, thiazine, anilide, adamantane, dithiocarbamate, brominated indanone, benzyl bromacetate or inorganic salts, and derivatives thereof. Moreover, the arch chemical company make, brand name proxel GXL (S), proxel XL-2 (S), etc. are mentioned.

  Specific 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. .

  As the pH adjuster, a substance capable of controlling the pH of the ink to usually 5 to 11, preferably 7 to 10 can be used. Specific examples thereof include, for example, the neutralizing agent described above; 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; and And inorganic bases such as disodium phosphate;

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

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

  Examples of water-soluble ultraviolet absorbers include, for example, sulfonated benzophenone, benzotriazole, salicylic acid, cinnamic acid, triazine, and other compounds, and derivatives thereof.

  As an example of the antioxidant, for example, an anti-fading agent can be used. Examples of the anti-fading agent include hydroquinone, alkoxyphenol, dialkoxyphenol, phenol, aniline, amine, indane, chroman, alkoxyaniline, and heterocyclic compounds, and derivatives thereof.

  Examples of the surfactant include known surfactants such as anion, cation, nonion, amphoteric, silicone-based and fluorine-based.

  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, diethylsulfosuccinate, diethylhexylsulfosuccinate, dioctylsulfosuccinate and the like. As an anionic surfactant, various types of products can be easily purchased, for example, as Daiten Kogyo Seiyaku Co., Ltd.'s Hytenol and Neo Haitenol series.

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

  Nonionic surfactants include ethers such as polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether; Ester systems such as polyoxyethylene 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 Acetylene glycol (alcohol) type such as lu-1-hexyn-3-ol; trade name Surfynol 104, 105PG50, 82, 420, 440, 465, 485, Olfin STG; For example, SIGMA-ALDRICH's TergItol 15-S-7 etc.);

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

  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 DuPont's Zonyl and Capstone series, Big Chemie's BYK series, etc., Omninova, DIC Corporation, and the like.

Specific examples of the antifoaming agent include silicone, silica mineral oil, olefin, and acetylene. Examples of commercially available antifoaming agents include Surfinol DF37, DF58, DF-110D, DF220, MD-20, and Olfine SK-14, all manufactured by Shin-Etsu Chemical Co., Ltd.
When using an antifoamer, the addition amount is preferably 0.01 to 5%, more preferably 0.03 to 3%, and even more preferably 0.05 to 1% with respect to the total mass of the liquid to be added. . The effect as an antifoamer is acquired by setting it as 0.01% or more, and dispersion stability becomes favorable by setting it as 5% or less.

  Microfiltration can be performed on the ink. When performing microfiltration, a membrane filter and / or glass filter paper or the like can be used. When the ink is used for ink jet recording, it is preferable to perform microfiltration. The pore diameter of a filter or the like when performing microfiltration is usually 0.5 μm to 20 μm, preferably 0.5 μm to 10 μm.

  The surface tension of the ink is usually 10 to 50 mN / m, preferably 20 to 40 mN / m. The viscosity of the ink is usually 30 mPa · s or less, preferably 20 mPa · s or less. The lower limit is preferably 0.1 mPa · s or more.

When the ink is used for inkjet recording, it is preferable to remove inorganic impurities in the ink. Examples of inorganic impurities include metal cation chloride (for example, sodium chloride) and sulfate (for example, sodium sulfate). The content of inorganic impurities is preferably 1% or less with respect to the total mass of the colorant contained in the ink. The lower limit can be below the detection limit of the analytical instrument.
As a method for removing inorganic impurities, for example, a method using a reverse osmosis membrane; a method in which a coloring agent is suspended and purified in a mixed solvent of a water-soluble organic solvent and water; and a method in which inorganic impurities are adsorbed with an ion exchange resin And the like.

The ink can be used as a water-based ink in various recording / printing fields. For example, it is suitable for applications such as writing, printing, information recording, and textile printing. In particular, it is preferably used for ink jet recording.
Examples of the ejection method of the ink jet printer 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;

  The recording medium means a substance to which the ink can adhere. The material is not limited as long as the ink can be attached. Among such recording media, for example, coated paper such as finely coated paper, art paper, coated paper, matte paper and cast paper; all of which have no ink-receiving layer, plain paper, gravure printing and offset printing Media used for ink-jets; ink-jet exclusive paper, ink-jet exclusive film, glossy paper, glossy film, etc. having an ink-receiving layer; fiber and cloth (cellulose, nylon, wool, etc.); leather; color filter substrate; and pressure bonding Paper or the like is preferred. A recording medium to which the ink is attached is also included in the scope of the present invention.

  When recording on a recording medium by the inkjet recording method, an inkjet printer having a container containing the ink can be used. An ink jet printer having a container containing the ink is also included in the scope of the present invention.

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

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by a following example.
Unless otherwise specified, the synthesis reaction and the like were carried out with stirring. Moreover, reaction temperature means the temperature in a reaction system.
The carbon black used in the examples is NIPEX 160IQ manufactured by ORION.
In addition, Joncryl 678 is an alkali-soluble resin having a weight average molecular weight of 8500, and Joncryl 690 is a weight average molecular weight of 16,700.

[Production Example 1] Preparation of polymer.
By following [Preparation Example 5] of Patent Document 2, a polymer emulsion having an acid value of 13 KOH mg / g, Tg of 9 ° C., and a solid content of 25% was obtained. This is designated as “Polymer 1”.

[Production Example 2] Preparation of aqueous solution of alkali-soluble resin.
Joncryl 678 (20 parts) and 8 parts of triethanolamine were added to 72 parts of ion-exchanged water and heated to 80 ° C. to obtain a solution, whereby an aqueous solution having a concentration of alkali-soluble resin of 20% was obtained. This is designated as “resin 1”.

[Production Example 3] Preparation of aqueous solution of alkali-soluble resin for comparison.
Joncrill 690 (20 parts) and triethanolamine 8.9 parts were added to ion-exchanged water 71.1 parts and heated to 80 ° C. to obtain a solution, whereby the concentration of the comparative alkali-soluble resin was 20%. An aqueous solution of was obtained. This is designated as “Comparative Resin 1”.

[Production Example 4] Preparation of dispersion 1.
Joncryl 678 (5.6 parts) and 3.2 parts of triethanolamine were dissolved in 103.7 parts of ion-exchanged water and stirred for 1 hour. 37.5 parts of carbon black was added to the obtained solution, and dispersion treatment was performed with a sand grinder for 20 hours under the condition of 1500 rpm to obtain a liquid. After 150 parts of ion-exchanged water was added dropwise to the obtained liquid, this liquid was filtered to remove the dispersing beads, thereby obtaining a dispersion having a pigment concentration of 12.5%. This is designated as “Dispersion 1”.

[Production Example 5] Preparation of dispersion 2.
Joncryl 678 (11.3 parts) and 6.4 parts of triethanolamine were dissolved in 94.8 parts of ion-exchanged water and stirred for 1 hour. 37.5 parts of carbon black was added to the obtained solution, and dispersion treatment was performed with a sand grinder for 20 hours under the condition of 1500 rpm to obtain a liquid. After 150 parts of ion-exchanged water was added dropwise to the obtained liquid, this liquid was filtered to remove the dispersing beads, thereby obtaining a dispersion having a pigment concentration of 12.5%. This is designated as “Dispersion 2”.

[Production Example 6] Preparation of dispersion 3.
Joncryl 678 (14.1 parts) and 8 parts of triethanolamine were dissolved in 90.4 parts of ion-exchanged water and stirred for 1 hour. 37.5 parts of carbon black was added to the obtained solution, and dispersion treatment was performed with a sand grinder for 20 hours under the condition of 1500 rpm to obtain a liquid. After 150 parts of ion-exchanged water was added dropwise to the obtained liquid, this liquid was filtered to remove the dispersing beads, thereby obtaining a dispersion having a pigment concentration of 12.5%. This is designated as “Dispersion 3”.

[Production Example 7] Preparation of dispersion 4.
Joncryl 678 (16.9 parts) and 9.6 parts of triethanolamine were dissolved in 86 parts of ion-exchanged water and stirred for 1 hour. 37.5 parts of carbon black was added to the obtained solution, and dispersion treatment was performed with a sand grinder for 20 hours under the condition of 1500 rpm to obtain a liquid. After 150 parts of ion-exchanged water was added dropwise to the obtained liquid, this liquid was filtered to remove the dispersing beads, thereby obtaining a dispersion having a pigment concentration of 12.5%. This is designated as “Dispersion 4”.

[Production Example 8] Preparation of dispersion 5.
Joncryl 678 (5.6 parts) and 3.2 parts of triethanolamine were dissolved in 103.7 parts of ion-exchanged water and stirred for 1 hour. 37.5 parts of carbon black was added to the obtained solution, and dispersion treatment was performed with a sand grinder for 20 hours under the condition of 1500 rpm to obtain a liquid. After 150 parts of ion-exchanged water was added dropwise to the obtained liquid, this liquid was filtered to remove the dispersing beads, thereby obtaining a dispersion having a pigment concentration of 12.5%. This is designated as “Dispersion 5”.

[Production Example 9] Preparation of dispersion 6.
Joncryl 678 (20.3 parts) and 11.6 parts of triethanolamine were dissolved in 80.6 parts of ion-exchanged water and stirred for 1 hour. 37.5 parts of carbon black was added to the obtained solution, and dispersion treatment was performed with a sand grinder for 20 hours under the condition of 1500 rpm to obtain a liquid. After 150 parts of ion-exchanged water was added dropwise to the obtained dispersion, this liquid was filtered to remove the dispersion beads, thereby obtaining a dispersion having a pigment concentration of 12.5%. This is designated as “Dispersion 6”.

[Production Example 10] Preparation of dispersion 7.
Joncryl 690 (11.3 parts) and 7.2 parts of triethanolamine were dissolved in 94 parts of ion-exchanged water and stirred for 1 hour. 37.5 parts of carbon black was added to the obtained solution, and dispersion treatment was performed with a sand grinder for 20 hours under the condition of 1500 rpm to obtain a liquid. After 150 parts of ion-exchanged water was added dropwise to the obtained dispersion, this liquid was filtered to remove the dispersion beads, thereby obtaining a dispersion having a pigment concentration of 12.5%. This is designated as “Dispersion 7”.

[Examples 1 to 8] Preparation of ink.
After mixing each component described in the following Table 2, each ink of Examples 1 to 3 for evaluation test and Comparative Examples 1 to 3 was obtained by filtering with a membrane filter having a pore size of 3 μm.
In Table 2, the numerical value of each component means “part”. The remaining part means that the total amount of ink is adjusted to 100 parts by adding ion exchange water as water.
The abbreviations in Table 2 have the following meanings.
PG: Propylene glycol.
1,2-HD: 1,2-hexanediol.
DF-110D: Surfynol DF-110D.
GXL (S): Proxel GXL (S).
Moreover, in Table 2, polymer 1 and resin 1 are solid content conversion values.

[Comparative Examples 1 to 8] Preparation of comparative ink.
Inks of Comparative Examples 1 to 8 were prepared in the same manner as in Examples 1 to 8, except that the components shown in Table 3 below were mixed instead of Table 2. The abbreviations in Table 3 below have the same meaning as in Table 2 above.
Moreover, in Table 3, all of the polymer 1, resin 1, and comparative resin 1 are solid content conversion values.

[Preparation of inkjet printer]
After the containers (also referred to as ink tanks) containing the inks of the respective Examples and Comparative Examples were loaded into an ink jet printer manufactured by Seiko Epson Corporation, product name PX205, the following initial discharge properties, discharge stability, and transfer were described below. Each test of bar code reading was performed.

[Initial discharge test]
After performing “head cleaning” which is a function of the ink jet printer, “nozzle check” was performed as initial ejection. The pin missing state observed in this nozzle check was evaluated according to the following four evaluation criteria. The evaluation results are shown in Table 3 below.
[Evaluation criteria for initial ejection properties]
A: No pin chipping is observed in one head cleaning.
B: No pin chipping is observed in the head cleaning within 3 times.
C: No pin chipping is observed in the head cleaning within 5 times.
D: Pin chipping is observed even after five head cleanings.

[Discharge stability test]
In the [Initial Discharge Properties Test], head cleaning was performed until no pin chip was observed, and then solid printing was performed on A4 paper. After this printing, the “nozzle check” was performed again, and the observed state of missing pins was evaluated according to the following four evaluation criteria. The evaluation results are shown in Table 3 below.
[Evaluation criteria for ejection stability]
A: No pin chipping is observed.
B: Pin chipping is observed with 1 to 3 nozzles.
C: Pin chipping is observed with 4 to 6 nozzles.
D: Pin chipping of 7 nozzles or more is observed.

[Transferability test]
Using the inkjet printer, a 1 cm × 1 cm square was solid printed on a pressure-bonded paper (POSTEX 107WH manufactured by Toppan Forms) and dried at 70 ° C. for 1 minute. The obtained crimped paper after printing was crimped. The pressure-bonded paper was peeled off, and the transfer state of the ink from the printing surface of the pressure-sensitive paper to the white paper surface was visually evaluated according to the following four evaluation criteria. The evaluation results are shown in Table 3 below.
[Evaluation criteria for transferability]
A: Transfer is not observed.
B: Extremely fine transfer is observed.
C: Transcription is clearly observed.
D: A very large amount of transfer is observed.

[Bar code reading test]
Using the inkjet printer, a barcode of the EAN128 standard was printed on a pressure-bonded paper (POSTEX 107WH manufactured by Toppan Forms). It was evaluated whether or not the obtained barcode could be read by a barcode verifier manufactured by Honeywell, Quick Check PC600.
As a result, it was confirmed that the inks of the respective examples could be read by the bar code verifier.

[Storage stability test]
The storage stability of each of the inks of Examples and Comparative Examples was tested by the following changes in “particle diameter (D90)” and “viscosity”.
[Particle diameter change test]
100 ml of each ink was collected in a sample bottle, sealed, and stored at 60 ° C. for 1 week. Each sample after storage was cooled to room temperature, and then the particle diameter of each ink was measured. The change rate of the particle diameter after storage with respect to the initial value was evaluated according to the following four evaluation criteria. The evaluation results are shown in Table 4 and Table 5 below. Microtrac (manufactured by Microtrack Bell Co., Ltd.) was used for measuring the particle diameter.
[Evaluation criteria for particle size]
A: Change rate is within ± 5%.
B: Change rate is within ± 10%.
C: Change rate is within ± 20%.
D: The rate of change is greater than ± 20%.

[Viscosity change test]
The viscosity before and after the test of the same sample as the [Particle Size Change Test] was measured, and the change rate of the particle size after storage with respect to the initial value was evaluated according to the following four evaluation criteria. The evaluation results are shown in Table 4 and Table 5 below. A rotational viscometer (R115 viscometer, manufactured by Toki Sangyo Co., Ltd.) was used for measuring the viscosity.
[Viscosity Evaluation Criteria]
A: Change rate is within ± 3%.
B: Change rate is within ± 5%.
C: Change rate is within ± 10%.
D: The rate of change is greater than ± 10%.

  As is apparent from the results of Tables 4 and 5, the ink of each comparative example, except for Comparative Example 4, is evaluated as “D” and is not practical. Comparative Example 4 showed a relatively good evaluation result. However, Comparative Example 4 is not practical because the transferability is “C” and contamination of the pressure-bonded paper is observed. On the other hand, it was confirmed that the inks of the respective examples had practical results and were practical.

  The ink of the present invention is excellent in transferability, barcode reading property, initial discharge property, discharge stability, and storage stability. For this reason, it is extremely suitable for various recording applications, in particular, inkjet recording using pressure-sensitive paper.

Claims (11)

An ink containing a water-insoluble colorant, an alkali-soluble resin, a polymer, and water, wherein the polymer is a polymer composed of three types of methacrylic acid derivatives and one type of acrylic acid derivative, and the alkali-soluble The weight average molecular weight of the resin is 1500 to 10,000, and the content (AW) of the alkali-soluble resin and the content (BW) of the polymer with respect to the total mass of the ink are expressed by the following formulas (1) and ( Ink satisfying both of 2).
Formula (1): AW / BW = greater than 0.4 and less than 1.5.
Formula (2): AW + BW = 2.4 mass%-4.5 mass%.   The ink according to claim 1, wherein the alkali-soluble resin is a water-insoluble colorant dispersant.   The ink according to claim 1, wherein the content of the polymer with respect to the total mass of the ink is 1 to 2.5% by mass.   The ink according to claim 1, wherein the alkali-soluble resin is a styrene-acrylic resin.   The ink according to claim 1, wherein the polymer is a polymer composed of methacrylic acid, two types of alkyl methacrylate, and alkyl acrylate.   The ink according to any one of claims 1, 3 and 5, wherein the polymer is a polymer composed of methacrylic acid, two types of C1-C3 alkyl methacrylate, and C6-C10 alkyl acrylate.   Furthermore, the ink as described in any one of Claims 1-6 containing a water-soluble organic solvent.   An ink jet recording method for performing recording by ejecting the ink droplets according to any one of claims 1 to 7 in accordance with a recording signal and attaching the ink droplets to a recording medium.   The ink jet recording method according to claim 8, wherein the recording medium is a pressure-bonded paper.   A recording medium to which the ink according to claim 1 is attached.   An ink-jet printer provided with the container containing the ink as described in any one of Claims 1-7.