Water-based inkjet ink

Abstract

To provide an aqueous inkjet ink which has excellent ejectability and continuous ejectability and can form a coating film having excellent scratch resistance.SOLUTION: Provided is an aqueous inkjet ink, comprising pigment, fine resin particles, a surfactant, and water. A content of the fine resin particles is 0.5 to 10 mass% as a solid relative to the whole mass of the aqueous inkjet ink. As the surfactant, there is included a surfactant represented by the following general formula (I) in an amount of 0.01 to 1 mass% relative to the whole mass of aqueous inkjet ink. (In the general formula (I), R1 is a C1-15 linear or branched substituent containing a hydroxyl group and / or an ether structure.)SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to an aqueous inkjet ink. [Background technology]

[0002] Water-based inkjet inks are widely used in various fields due to their high safety and low environmental impact.

[0003] For example, Patent Document 1 discloses an aqueous inkjet ink comprising at least water (A), a colorant (B), a water-soluble organic solvent component (C), a surfactant (D), and resin fine particles (E), wherein the aqueous inkjet ink further comprises a water-soluble carbodiimide compound (F) as a crosslinking component, the surfactant (D) is a silicone-based surfactant, the resin fine particles (E) have a functional group that reacts with a carbodiimide group at least on their surface, and the mass ratio (E) / (F) of the resin fine particles (E) to the water-soluble carbodiimide compound (F) is 10 or more. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2018-070827 [Overview of the project] [Problems that the invention aims to solve]

[0005] Patent Document 1 describes how the ink coating is prevented from being removed by friction (streaking) by using specific resin microparticles and a silicone-based surfactant (resistance to abrasion).

[0006] However, conventional water-based inkjet inks do not have sufficient ejection performance, and especially when printing continuously, image quality degradation such as streaks can occur (poor continuous ejection performance). There was room for further improvement in balancing ejection performance and abrasion resistance.

[0007] Therefore, the present invention aims to provide an aqueous inkjet ink that can form a coating film with excellent ejection properties, continuous ejection properties, and abrasion resistance.

[0008] The inventors of the present invention have found that all of the above-mentioned problems can be solved by setting the content of resin fine particles within a predetermined range and using a specific surfactant in an aqueous inkjet ink containing pigment, resin fine particles, surfactant, and water, and have completed the present invention.

[0009] In other words, the present invention relates to an aqueous inkjet ink comprising a pigment, resin fine particles, a surfactant, and water, wherein the content of the resin fine particles is 0.5 to 10% by mass in terms of solid content relative to the total mass of the aqueous inkjet ink, and the surfactant is an aqueous inkjet ink comprising 0.01 to 1% by mass of a surfactant represented by the following general formula (I) relative to the total mass of the aqueous inkjet ink.

[0010] [ka] (In general formula (I), R 1 (These substituents include a hydroxyl group and / or an ether structure, and are linear or branched chains having 1 to 15 carbon atoms.)

[0011] In the aqueous inkjet ink of the present invention, R in the above general formula (I) 1 However, it is preferable that it contains a hydroxyl group. Furthermore, in the above general formula (I), R 1 However, it is preferable that it contains a hydroxyl group and an ether structure. Furthermore, in the above general formula (I), R 1 It is preferable that the carbon number is between 2 and 11. Furthermore, it is preferable that the surfactant further includes a nonionic surfactant and / or anionic surfactant. Furthermore, it is preferable that the amount of surfactant represented by the above general formula (I) is 0.1 to 0.5% by mass relative to the total mass of the aqueous inkjet ink. Furthermore, it is preferable that the resin fine particles are at least one selected from the group consisting of polyethylene resin, acrylic resin, styrene-acrylic copolymer resin, vinyl acetate-acrylic copolymer resin, vinyl chloride-acrylic copolymer resin, vinyl acetate resin, polyester urethane resin, polyether polyurethane resin, polycarbonate urethane resin, and polyester resin. Furthermore, it is preferable that the content of the resin fine particles is 1 to 5% by mass in terms of solid content relative to the total mass of the aqueous inkjet ink. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide an aqueous inkjet ink that can form a coating film with excellent ejection properties, continuous ejection properties, and abrasion resistance. [Modes for carrying out the invention]

[0013] The aqueous inkjet ink of the present invention is an aqueous inkjet ink comprising a pigment, resin fine particles, a surfactant, and water, wherein the content of the resin fine particles is 0.5 to 10% by mass in terms of solid content relative to the total mass of the aqueous inkjet ink, and the surfactant is a surfactant represented by the following general formula (I) in an amount of 0.01 to 1% by mass relative to the total mass of the aqueous inkjet ink.

[0014] [ka] (In general formula (I), R 1 (These substituents include a hydroxyl group and / or an ether structure, and are linear or branched chains having 1 to 15 carbon atoms.)

[0015] In the present invention, the abrasion resistance of the ink film can be improved by blending 0.5 to 10% by mass of resin fine particles. Further, generally, when resin fine particles are blended, the ejection property and continuous ejection property in inkjet printing tend to deteriorate. However, by adding the surfactant represented by the general formula (I), the refillability (re-supply performance) of the aqueous inkjet ink in the flow path is improved, so that even if a certain amount of resin fine particles are blended, the ejection property and continuous ejection property of the aqueous inkjet ink can be improved. However, the present invention may not be construed as being limited to the above mechanism.

[0016] (Pigment) The aqueous inkjet ink of the present invention contains a pigment.

[0017] As the above pigment, known pigments may be appropriately selected.

[0018] Examples of organic pigments include azo pigments (e.g., azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, etc.), polycyclic pigments (e.g., phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc.), dye chelates (e.g., basic dye type chelates, acidic dye type chelates, etc.), nitro pigments, nitroso pigments, aniline black, etc.

[0019] Examples of inorganic pigments include titanium oxide, zinc white, zinc sulfide, lead white, calcium carbonate, precipitated barium sulfate, white carbon, alumina white, kaolin clay, talc, bentonite, black iron oxide, cadmium red, red iron oxide, molybdenum red, molybdate orange, chrome vermilion, lead yellow, cadmium yellow, yellow iron oxide, titanium yellow, chromium oxide, viridian, titanium cobalt green, cobalt green, cobalt chromium green, victoria green, ultramarine, dark blue, cobalt blue, celian blue, cobalt silica blue, cobalt zinc silica blue, manganese violet, cobalt violet, etc.

[0020] The pigment content is preferably 1 to 20% by mass, and more preferably 3 to 10% by mass, relative to the total mass of the aqueous inkjet ink.

[0021] (Resin fine particles) The aqueous inkjet ink of the present invention contains resin fine particles.

[0022] Examples of the above-mentioned resin fine particles include polyethylene resin, polypropylene resin, urethane resin, acrylic resin, styrene resin, styrene-acrylic copolymer resin, butadiene resin, styrene-butadiene copolymer resin, vinyl acetate resin, vinyl acetate-acrylic copolymer resin, vinyl chloride resin, vinyl chloride-acrylic copolymer resin, fluoroolefin resin, polyester urethane resin, polyether polyurethane resin, polycarbonate urethane resin, and polyester resin.

[0023] The above-mentioned resin fine particles are preferably at least one selected from the group consisting of polyethylene resin, acrylic resin, styrene-acrylic copolymer resin, vinyl acetate resin, vinyl acetate-acrylic copolymer resin, vinyl chloride-acrylic copolymer resin, polyester urethane resin, polyether polyurethane resin, polycarbonate urethane resin, and polyester resin, from the viewpoint of suitably imparting abrasion resistance, and more preferably at least one selected from the group consisting of polyethylene resin, styrene-acrylic copolymer resin, polyester urethane resin, and polyether polyurethane resin.

[0024] The above-mentioned resin fine particles may be composed of one type of resin, or they may be composed of two or more types of resin.

[0025] The volume-average particle size of the above resin fine particles is preferably 10 to 1000 nm, more preferably 30 to 500 nm, and even more preferably 50 to 300 nm. The volume-average particle size can be determined, for example, using a particle size distribution analyzer.

[0026] The content of the above-mentioned resin fine particles is 0.5 to 10% by mass in terms of solid content relative to the total mass of the water-based inkjet ink. If the content of the above-mentioned resin fine particles is less than 0.5% by mass of the total mass of the water-based inkjet ink in terms of solid content, the abrasion resistance will be insufficient, and if it exceeds 10% by mass of solid content, the ejection performance and continuous ejection performance will be insufficient.

[0027] From the viewpoint of appropriately imparting storage stability, the content of the above resin fine particles is preferably 1% by mass or more in terms of solid content relative to the total mass of the aqueous inkjet ink. Furthermore, from the viewpoint of appropriately imparting abrasion resistance, the solid content is preferably 8% by mass or less, and more preferably 5% by mass or less, relative to the total mass of the aqueous inkjet ink.

[0028] (Surfactants) The aqueous inkjet ink of the present invention contains a surfactant represented by the following general formula (I) as a surfactant.

[0029] [ka] (In general formula (I), R 1 (These substituents include a hydroxyl group and / or an ether structure, and are linear or branched chains having 1 to 15 carbon atoms.)

[0030] In the above general formula (I), R 1 However, from the viewpoint of appropriately imparting storage stability to aqueous inkjet inks, it is preferable to include a hydroxyl group, and more preferable to include both a hydroxyl group and an ether structure.

[0031] In the above general formula (I), R 1 From the viewpoint of suitably improving the storage stability and refillability of the aqueous inkjet ink, the carbon number is preferably 2 to 11, and more preferably 4 to 11.

[0032] Specific examples of surfactants represented by the above general formula (I) include 2-{[2-hydroxy-3-(octyloxy)propyl]sulfanyl}ethane-1-ol, 2,2'-thiodiethanol, and 1-[(2-hydroxyethyl)thio]-2-propanol. In particular, 2-{[2-hydroxy-3-(octyloxy)propyl]sulfanyl}ethane-1-ol is preferred from the viewpoint of suitably improving the storage stability and refillability of water-based inkjet inks.

[0033] The aqueous inkjet ink of the present invention contains 0.01 to 1% by mass of the surfactant represented by the above general formula (I) based on the total mass of the aqueous inkjet ink. If the surfactant content shown in the above general formula (I) is less than 0.01% by mass, continuous dispensing and abrasion resistance will decrease, and if it exceeds 1% by mass, storage stability, dispensing, continuous dispensing, and abrasion resistance will decrease.

[0034] The surfactant represented by the above general formula (I) is preferably present in an amount of 0.1% by mass or more relative to the total mass of the aqueous inkjet ink, from the viewpoint of suitably imparting continuous discharge properties. Furthermore, from the viewpoint of suitably imparting storage stability and discharge properties, it is preferably 0.8% by mass or less, more preferably 0.6% by mass or less, and even more preferably 0.5% by mass or less, relative to the total mass of the aqueous inkjet ink.

[0035] From the viewpoint of further improving ejection performance, the aqueous inkjet ink of the present invention preferably further contains a nonionic surfactant and / or an anionic surfactant.

[0036] Examples of the nonionic surfactants mentioned above include polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkyl ethers, polyoxyethylene alkylamines, polyoxyethylene alkylamides, polyoxyethylene propylene block polymers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyethersiloxane copolymers, and ethylene oxide adducts of acetylene alcohols.

[0037] Examples of the above-mentioned anionic surfactants include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, lauryl salt, sodium sulfate, and salts of polyoxyethylene alkyl ether sulfate.

[0038] The content of the above-mentioned nonionic surfactant and / or anionic surfactant is preferably 0.1 to 1% by mass. The above-mentioned nonionic surfactants and / or anionic surfactants may be used alone or in combination of two or more types.

[0039] (water) The aqueous inkjet ink of the present invention contains water.

[0040] From the viewpoint of appropriately imparting discharge properties and storage stability, the water content is preferably about 15 to 70% by mass relative to the total mass of the aqueous inkjet ink.

[0041] (Water-soluble solvent) The aqueous inkjet ink of the present invention may contain a water-soluble solvent.

[0042] The above-mentioned water-soluble solvents are not particularly limited and can include monoalcohols, trihydric alcohols, dihydric alcohols, polyhydric alcohols of tetrahydric or higher hydric values, lower alkyl ethers of polyhydric alcohols, ketones, ethers, esters, nitrogen-containing compounds, and the like. These may be used individually or in combination of two or more.

[0043] From the viewpoint of appropriately imparting discharge properties and storage stability, the content of the above-mentioned water-soluble solvent is preferably about 15 to 70% by mass relative to the total mass of the aqueous inkjet ink.

[0044] (Pigment dispersant) The aqueous inkjet ink of the present invention may contain a pigment dispersant.

[0045] Examples of the above-mentioned pigment dispersants include carbodiimide-based dispersants, polyesteramine-based dispersants, fatty acid amine-based dispersants, modified polyacrylate-based dispersants, modified polyurethane-based dispersants, polychain polymer nonionic dispersants, and polymer ionic surfactants. These pigment dispersants can be used individually or in combination of two or more types.

[0046] As the pigment dispersant, a copolymer of styrene, alkyl (meth)acrylate, and (meth)acrylic acid is more preferred, a copolymer of (meth)acrylic acid and stearyl (meth)acrylate or a copolymer of styrene and lauryl (meth)acrylate is even more preferred, and a copolymer of (meth)acrylic acid, stearyl (meth)acrylate, and styrene is particularly preferred. Note that (meth)acrylate means acrylate and / or methacrylate, and (meth)acrylic acid means acrylic acid and / or methacrylic acid.

[0047] The amount of the pigment dispersant is preferably 1 to 200 parts by mass, and more preferably 5 to 100 parts by mass, per 100 parts by mass of the pigment.

[0048] (Other additives) The aqueous inkjet ink of the present invention may optionally contain various additives such as ultraviolet absorbers, antioxidants, defoamers, preservatives, fungicides, rust inhibitors, thickeners, humectants, and pH adjusters. The amount of the above-mentioned additives is, for example, about 0 to 10% by mass in terms of solid content relative to the total mass of the water-based inkjet ink.

[0049] (Method of manufacturing water-based inkjet ink) The method for producing the aqueous inkjet ink of the present invention is not particularly limited; for example, the above components may be added sequentially or simultaneously, followed by mixing, stirring, and kneading. When mixing and stirring the above components in order, for example, a pigment dispersant may be mixed with water or a water-soluble solvent to obtain an aqueous resin varnish, then the pigment may be mixed and stirred to prepare an aqueous pigment ink base, and then resin fine particles, a surfactant, and, if necessary, water or a water-soluble solvent may be mixed, stirred, and kneaded to prepare an aqueous inkjet ink.

[0050] The method for mixing, stirring, and kneading the meat described above is not particularly limited, and may be used in known ways, such as using a bead mill, ready mill, ultrasonic homogenizer, high-pressure homogenizer, paint shaker, ball mill, roll mill, sand mill, sand grinder, Dino mill, Dispermat, SC mill, nanomizer, etc.

[0051] (Physical properties of water-based inkjet inks) The aqueous inkjet ink of the present invention preferably exhibits excellent storage stability. Storage stability can be evaluated by the following method.

[0052] Water-based inkjet ink is collected in a glass bottle, and its viscosity at 25°C is measured using a viscometer (RE100L model, manufactured by Toki Sangyo Co., Ltd.). Afterward, the container is sealed tightly and stored at 60°C for one month. The viscosity after storage (at 25°C) is then measured using the viscometer described above. Storage stability is evaluated by the viscosity change rate (at 60°C, (viscosity after 1 month - viscosity before storage) / viscosity before storage). If the viscosity change rate is less than 10%, it can be evaluated as having excellent storage stability. If the viscosity change rate is less than 5%, it can be evaluated as having extremely excellent storage stability.

[0053] The aqueous inkjet ink of the present invention exhibits excellent ejection properties. Discharge performance can be evaluated by the following method.

[0054] We will fill cartridges of an Epson PX105 printer with water-based inkjet ink, print, and evaluate the ink ejection performance. Even if there are some printing irregularities, if the material can be ejected, it can be evaluated as having excellent ejection performance. If there are no printing irregularities and the material can be ejected stably, it can be evaluated as having extremely excellent ejection performance. Furthermore, if the water-based inkjet ink is black, cyan, magenta, or yellow, printing will be performed on GL-101A450 photo paper (manufactured by Canon), and if the water-based inkjet ink is white, printing will be performed on light-shielding paper.

[0055] The aqueous inkjet ink of the present invention exhibits excellent continuous ejection properties. Continuous dispensing performance can be evaluated by the following method.

[0056] We will fill cartridges of an Epson PX105 printer with water-based inkjet ink, print 50 solid images of 15cm x 20cm in succession, and evaluate the continuous ink ejection performance. The print quality of the printed material obtained by the above printing method is good, and if the water-based inkjet ink can be ejected stably, it can be evaluated as having excellent continuous ejection properties. Furthermore, if the water-based inkjet ink is black, cyan, magenta, or yellow, printing will be done on GL-101A450 photo paper (manufactured by Canon), and if the water-based inkjet ink is white, printing will be done on light-blocking paper.

[0057] The aqueous inkjet ink of the present invention has excellent abrasion resistance. Abrasion resistance can be evaluated by the following method.

[0058] After the print obtained from the evaluation of continuous ejection performance described above is dried in an 80°C oven for 3 minutes, the abrasion resistance is evaluated by rubbing the printed surface with a cotton swab. If, after rubbing the printed surface with a cotton swab 10 times, some color transfers to the swab and the rubbed area is only slightly faded, the surface can be evaluated as having excellent abrasion resistance. If, even after rubbing the printed surface with a cotton swab 10 times, there is no fading at all, the surface can be evaluated as having extremely excellent abrasion resistance. [Examples]

[0059] The present invention will be specifically described below using examples, but the present invention is not limited to these examples without departing from its spirit and scope. Unless otherwise specified, in these examples, "parts" and "%" represent "parts by mass" and "mass%", respectively.

[0060] <Preparation of water-based pigment ink base> (Water-based resin varnish) A 30% solids aqueous resin varnish was prepared by dissolving 30 parts by mass of acrylic acid / stearyl acrylate / styrene copolymer in a mixed solution of 3.8 parts by mass of potassium hydroxide and 66.2 parts by mass of water.

[0061] (Water-based black ink) A resin varnish for pigment dispersion was prepared by adding 48 parts by mass of water to 32 parts by mass of the above-mentioned aqueous resin varnish and mixing. To the above-mentioned pigment dispersion resin varnish, 20 parts by mass of carbon black (product name: Printex 90, manufactured by Degussa) were added, stirred and mixed, and then kneaded in a wet circulation mill to prepare an aqueous black ink base (pigment ratio = 20% by mass).

[0062] (Water-based cyan ink) A resin varnish for pigment dispersion was prepared by adding 48 parts by mass of water to 32 parts by mass of the above-mentioned aqueous resin varnish and mixing. To the above-mentioned resin varnish for pigment dispersion, 20 parts by mass of cyan pigment (product name: Heliogen Blue L7101F, manufactured by BASF) were added, stirred and mixed, and then kneaded in a wet circulation mill to prepare an aqueous cyan ink base (pigment ratio = 20% by mass).

[0063] (Water-based magenta ink) A resin varnish for pigment dispersion was prepared by adding 48 parts by mass of water to 32 parts by mass of the above-mentioned aqueous resin varnish and mixing. To the above-mentioned resin varnish for pigment dispersion, 20 parts by mass of magenta pigment (product name: Inkjet Magenta E5B02, manufactured by Clariant) were added, stirred and mixed, and then kneaded in a wet circulation mill to prepare an aqueous magenta ink base (pigment ratio = 20% by mass).

[0064] (Water-based yellow ink) A resin varnish for pigment dispersion was prepared by adding 48 parts by mass of water to 32 parts by mass of the above-mentioned aqueous resin varnish and mixing. 20 parts by mass of yellow pigment (product name: Novapalm Yellow 4G01, manufactured by Clariant) was added to the above-mentioned pigment dispersion resin varnish, stirred and mixed, and then kneaded in a wet circulation mill to prepare an aqueous yellow ink base (pigment ratio = 20% by mass).

[0065] (Water-based white ink) A resin varnish for pigment dispersion was prepared by adding 28 parts by mass of water to 32 parts by mass of the above-mentioned aqueous resin varnish and mixing. 40 parts by mass of titanium dioxide pigment (product name: CR-90, manufactured by Ishihara Sangyo Co., Ltd.) were added to the above-mentioned resin varnish for pigment dispersion, stirred and mixed, and then kneaded in a wet circulation mill to prepare an aqueous white ink base (pigment ratio = 40% by mass).

[0066] The materials used in the following examples and comparative examples are as follows.

[0067] <Resin fine particles> Polyethylene resin microparticles (product name: AQUACER531, manufactured by BYK Corporation) Acrylic resin microparticles (product name: Yodzol AD173, manufactured by Henkel) Styrene-acrylic copolymer resin microparticles (product name: NeoCryl A-1092, manufactured by Covestro) Vinyl acetate-acrylic copolymer resin fine particles (product name: Vinibran 1245L, manufactured by Nisshin Chemical Industry Co., Ltd.) Vinyl chloride-acrylic copolymer resin fine particles (product name: Vinibran 278, manufactured by Nisshin Chemical Industry Co., Ltd.) Vinyl acetate resin fine particles (product name: Vinibran GV6181, manufactured by Nisshin Chemical Industry Co., Ltd.) Polyester polyurethane resin microparticles (product name: Superflex 740, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) Polyether polyurethane resin microparticles (product name: NeoRez R-966, manufactured by Covestro) Polycarbonate polyurethane resin microparticles (product name: Superflex 420NS, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) Polyester resin microparticles (product name: Sepolion ES, manufactured by Sumitomo Seika Co., Ltd.)

[0068] <Surfactants> (Surfactants that satisfy the above general formula (I)) 2-{[2-hydroxy-3-(octyloxy)propyl]sulfanyl}ethane-1-ol 2,2'-Thiodiethanol 1-[(2-hydroxyethyl)thio]-2-propanol (Surfactants that do not satisfy the above general formula (I)) 2-(methylthio)ethanol 2-(ethylthio)ethanol 2-(isopropylthio)ethanol 2-(isobutylthio)ethanol 2-(n-propylthio)ethanol (Nonionic surfactant) Nonionic surfactant A (product name: SURFYNOL 465, manufactured by Nisshin Chemical Industry Co., Ltd.) Nonionic surfactant B (product name: Emulgen 705, manufactured by Kao Corporation) Nonionic surfactant C (product name: TEGO Glide 450, manufactured by Evonk) (Anionic surfactants) Anionic surfactant (product name: Persoft EF, manufactured by ADEKA)

[0069] <Water-soluble solvent> Propylene glycol Glycerin

[0070] <Water> purified water

[0071] (Examples 1-25, Comparative Examples 1-8) Each material was mixed and stirred in the proportions listed in Tables 1, 2, and 3 to prepare an aqueous inkjet ink.

[0072] <Storage stability> The prepared water-based inkjet ink was collected in a glass bottle, and its viscosity at 25°C was measured using a viscometer (RE100L model, manufactured by Toki Sangyo Co., Ltd.). The solution was then sealed tightly and stored at 60°C for one month. The viscosity after storage (at 25°C) was measured using the viscometer described above. Storage stability was evaluated based on the viscosity change rate (at 60°C, (viscosity after 1 month - viscosity before storage) / viscosity before storage) according to the following criteria. (Evaluation Criteria) ◎: Viscosity change rate was less than 5% ○: The viscosity change rate was 5% or more and less than 10%. ×: The viscosity change rate was 10% or more.

[0073] <Dischargeability> The prepared water-based inkjet ink was loaded into cartridges of an Epson PX105 printer, and printing was performed. The ejection performance was evaluated according to the following criteria. Furthermore, when using water-based inkjet ink in black, cyan, magenta, or yellow, printing was performed on GL-101A450 photo paper (manufactured by Canon), and when using water-based inkjet ink in white, printing was performed on light-shielding paper. (Evaluation Criteria) ◎: Printing was consistent and stable. ○: There was some printing irregularity, but it was possible to dispense the ink. ×: There were printing irregularities, and stable ejection was not possible.

[0074] <Continuous discharge> The prepared water-based inkjet ink was loaded into a cartridge of an Epson PX105 printer, and 50 solid images measuring 15cm x 20cm were printed consecutively. Continuous ejection performance was evaluated according to the following criteria. Furthermore, when using water-based inkjet ink in black, cyan, magenta, or yellow, printing was performed on GL-101A450 photo paper (manufactured by Canon), and when using water-based inkjet ink in white, printing was performed on light-blocking paper. (Evaluation Criteria) ○: The print quality of the printed material was good, and it was possible to eject the material stably. ×: The printed material showed streaks and other image degradation, and stable ejection was not possible.

[0075] <Abrasion resistance> After the print obtained from the evaluation of continuous ejection performance described above was dried in an 80°C oven for 3 minutes, the abrasion resistance was evaluated by rubbing the printed surface with a cotton swab according to the following evaluation criteria. (Evaluation Criteria) ◎: The printed surface remained completely unsmudged even after being rubbed 10 times with a cotton swab. ○: After rubbing the printed surface 10 times with a cotton swab, the color transferred to the cotton swab, and the rubbed area became slightly faded. △: After rubbing the printed surface 10 times with a cotton swab, a portion of the rubbed area peeled off. ×: After rubbing the printed surface 10 times with a cotton swab, the rubbed area completely peeled off.

[0076] [Table 1]

[0077] [Table 2]

[0078] [Table 3]

[0079] From the examples, it was confirmed that in an aqueous inkjet ink containing a pigment, resin microparticles, a surfactant, and water, by setting the content of the resin microparticles within a predetermined range and using a specific surfactant, a coating film excellent in storage stability, ejection property, continuous ejection property, and abrasion resistance can be formed. Particularly, in the example using 2-{[2-hydroxy-3-(octyloxy)propyl]sulfanyl}ethane-1-ol as the surfactant represented by the general formula (I), the ejection property was extremely excellent. Also, in the examples using polyethylene resin microparticles, styrene-acrylic copolymer resin microparticles, polyester urethane resin microparticles, or polyether polyurethane resin microparticles as the resin microparticles, the abrasion resistance was extremely excellent. On the other hand, in the comparative examples, a coating film excellent in all of the ejection property, continuous ejection property, and abrasion resistance could not be formed. In Comparative Examples 2 to 8, since a printed matter could not be obtained in the evaluation of the continuous ejection property, the evaluation of the abrasion resistance could not be performed (described as "-" in Table 3).

[0080] The following matters are disclosed in this specification.

[0081] The present disclosure (1) is an aqueous inkjet ink containing a pigment, resin microparticles, a surfactant, and water, wherein the content of the resin microparticles is 0.5 to 10% by mass in terms of solid content with respect to the total mass of the aqueous inkjet ink, and the surfactant contains, with respect to the total mass of the aqueous inkjet ink, 0.01 to 1% by mass of the surfactant represented by the following general formula (I).

Chemical formula

[0082] The present disclosure (2) is, in the above general formula (I), R 1However, it is an aqueous inkjet ink as described in disclosure (1) that contains a hydroxyl group. This disclosure (3) is that in the above general formula (I), R 1 However, the aqueous inkjet ink described in (1) or (2) of this disclosure comprises a hydroxyl group and an ether structure. This disclosure (4) is that in the above general formula (I), R 1 The aqueous inkjet ink described in any of (1) to (3) of this disclosure, wherein the carbon number of the carbon atoms is 2 to 11. Disclosure (5) is an aqueous inkjet ink according to any one of Disclosures (1) to (4), further comprising a nonionic surfactant and / or an anionic surfactant as the surfactant. Disclosure (6) is an aqueous inkjet ink according to any one of Disclosures (1) to (5), wherein the content of the surfactant represented by the general formula (I) is 0.1 to 0.5% by mass relative to the total mass of the aqueous inkjet ink. Disclosure (7) is an aqueous inkjet ink according to any one of Disclosures (1) to (6), wherein the resin fine particles are at least one selected from the group consisting of polyethylene resin, acrylic resin, styrene-acrylic copolymer resin, vinyl acetate-acrylic copolymer resin, vinyl chloride-acrylic copolymer resin, vinyl acetate resin, polyester urethane resin, polyether polyurethane resin, polycarbonate urethane resin, and polyester resin. Disclosure (8) is an aqueous inkjet ink according to any one of Disclosures (1) to (7), wherein the content of the resin fine particles is 1 to 5% by mass in terms of solid content relative to the total mass of the aqueous inkjet ink. [Industrial applicability]

[0083] According to the present invention, it is possible to provide an aqueous inkjet ink that can form a coating film with excellent ejection properties, continuous ejection properties, and abrasion resistance.

Claims

1. A water-based inkjet ink comprising a pigment, resin fine particles, a surfactant, and water, The content of the resin fine particles is 0.5 to 10% by mass in terms of solid content relative to the total mass of the aqueous inkjet ink. The aforementioned surfactant is an aqueous inkjet ink containing 0.01 to 1% by mass of a surfactant represented by the following general formula (I) relative to the total mass of the aqueous inkjet ink. 【Chemistry 1】 (In general formula (I), R １ (These substituents include a hydroxyl group and / or an ether structure, and are linear or branched chains having 1 to 15 carbon atoms.)

2. In the above general formula (I), R １ However, the aqueous inkjet ink according to claim 1, which contains a hydroxyl group.

3. In the above general formula (I), R １ However, the aqueous inkjet ink according to claim 1 or 2, comprising a hydroxyl group and an ether structure.

4. In the above general formula (I), R １ The aqueous inkjet ink according to claim 1 or 2, wherein the carbon number is 2 to 11.

5. The aqueous inkjet ink according to claim 1 or 2, further comprising a nonionic surfactant and / or an anionic surfactant as the surfactant.

6. The aqueous inkjet ink according to claim 1 or 2, wherein the content of the surfactant represented by the general formula (I) is 0.1 to 0.5% by mass relative to the total mass of the aqueous inkjet ink.

7. The aqueous inkjet ink according to claim 1 or 2, wherein the resin fine particles are at least one selected from the group consisting of polyethylene resin, acrylic resin, styrene-acrylic copolymer resin, vinyl acetate-acrylic copolymer resin, vinyl chloride-acrylic copolymer resin, vinyl acetate resin, polyester urethane resin, polyether polyurethane resin, polycarbonate urethane resin, and polyester resin.

8. The aqueous inkjet ink according to claim 1 or 2, wherein the content of the resin fine particles is 1 to 5% by mass in terms of solid content relative to the total mass of the aqueous inkjet ink.

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