Aqueous inkjet ink

Abstract

The purpose of the present invention is to provide an aqueous inkjet ink which has excellent ejection properties and continuous ejection properties and is capable of forming a coating film having excellent scratch resistance. The present invention relates to an aqueous inkjet ink containing a pigment, fine resin particles, a surfactant, and water, in which the content of the fine resin particles is 0.5-10 mass% in terms of solid content with respect to the total mass of the aqueous inkjet ink; the aqueous inkjet ink contains, as the surfactant, 0.01-1 mass% of a surfactant represented by general formula (I) with respect to the total mass of the aqueous inkjet ink. In general formula (I), R1 is a straight-chain or branched-chain substituent group containing a hydroxyl group and / or an ether structure and having 1-15 carbon atoms. And # imgabs0 #.

Description

Technical Field

[0001] The present invention relates to an aqueous inkjet ink. Background Art

[0002] Aqueous inkjet inks are highly safe and have a low environmental impact, and are thus used in a wide range of fields.

[0003] For example, Patent Document 1 discloses an aqueous inkjet ink characterized by containing 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 contains a water-soluble carbodiimide compound (F) as a crosslinking component, the surfactant (D) is a silicone surfactant (also referred to as a "silicone surfactant"), the resin fine particles (E) have a functional group reactive 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.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2018-070827 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] In Patent Document 1, by using specific resin fine particles and a silicone surfactant, the problem of ink film peeling (appearance of scratches / flying white) due to friction (scratch resistance) was suppressed.

[0009] However, conventional aqueous inkjet inks have a problem of insufficient ejection property, and particularly, image quality deterioration such as streaks occurs during continuous printing (poor continuous ejection property), and there is room for further improvement in achieving both ejection property and scratch resistance.

[0010] Therefore, an object of the present invention is to provide an aqueous inkjet ink having excellent ejection property and continuous ejection property and capable of forming a film with excellent scratch resistance.

[0011] The present inventors found that in an aqueous inkjet ink containing a pigment, resin fine particles, a surfactant, and water, by setting the content of the resin fine particles within a specified range and using a specific surfactant, all of the above problems can be solved, and thus completed the present invention.

[0012] That is, the present invention is an aqueous inkjet ink, which contains a pigment, resin particles, a surfactant, and water. Among them, the content of the resin particles is 0.5% by mass to 10% by mass relative to the total mass of the aqueous inkjet ink in terms of solid content; as the surfactant, it contains a surfactant represented by the following general formula (I) in an amount of 0.01% by mass to 1% by mass relative to the total mass of the aqueous inkjet ink.

[0013]

[0014] In the general formula (I), R 1 is a linear or branched substituent having 1 to 15 carbon atoms and containing a hydroxyl group and / or an ether structure.

[0015] In the aqueous inkjet ink of the present invention, in the general formula (I), R 1 preferably contains a hydroxyl group.

[0016] In addition, in the general formula (I), R 1 preferably contains a hydroxyl group and an ether structure.

[0017] In addition, in the general formula (1), R 1 preferably has 2 to 11 carbon atoms.

[0018] In addition, as the above surfactant, it is preferably further contains a nonionic surfactant and / or an anionic surfactant.

[0019] In addition, as the content of the surfactant represented by the general formula (I), it is preferably 0.1% by mass to 0.5% by mass relative to the total mass of the aqueous inkjet ink; In addition, the above resin particles are preferably at least one selected from the group consisting of a polyethylene resin, an acrylic resin, a styrene-acrylic copolymer resin, a vinyl acetate-acrylic copolymer resin, a vinyl chloride-acrylate copolymer resin, a vinyl acetate resin, a polyester polyurethane resin, a polyether polyurethane resin, a polycarbonate polyurethane resin, and a polyester resin.

[0020] In addition, the content of the above resin particles is preferably 1% by mass to 5% by mass relative to the total mass of the aqueous inkjet ink in terms of solid content.

[0021] Advantages of the Invention

[0022] Based on the present invention, it is possible to provide an aqueous inkjet ink with excellent ejection properties, continuous ejection properties, and capable of forming a film with excellent abrasion resistance. Detailed Embodiments

[0023] The aqueous inkjet ink of the present invention contains a pigment, resin particles, a surfactant, and water. Among them, the content of the resin particles is 0.5% to 10% by mass based on the total mass of the aqueous inkjet ink in terms of solid content; as the surfactant, it contains a surfactant represented by the following general formula (I) in an amount of 0.01% to 1% by mass based on the total mass of the aqueous inkjet ink.

[0024]

[0025] In the general formula (I), R 1 is a linear or branched substituent having 1 to 15 carbon atoms and containing a hydroxyl group and / or an ether structure.

[0026] In the present invention, by incorporating 0.5% to 10% by mass of resin particles, the abrasion resistance of the ink coating film can be improved. In addition, generally, when resin particles are incorporated, there is a tendency for the ejection property and continuous ejection property in inkjet printing to deteriorate. However, by adding the surfactant represented by the general formula (I), the refillability (re-supply property) of the aqueous inkjet ink in the flow path can be improved; thus, even if resin particles are incorporated to a certain extent, the ejection property and continuous ejection property of the aqueous inkjet ink can be improved.

[0027] It should be noted that the present invention may not be explained limited to the above mechanism.

[0028] (Pigment)

[0029] The aqueous inkjet ink of the present invention contains a pigment.

[0030] The pigment can be appropriately selected from known pigments.

[0031] As organic pigments, for example, azo pigments (such as azo lakes, insoluble azo pigments, condensed azo pigments, chelated azo pigments, etc.), polycyclic pigments (such as phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc.), dye chelates (such as basic dye type chelates, acid dye type chelates, etc.), nitro pigments, nitroso pigments, aniline black, etc. can be mentioned.

[0032] As inorganic pigments, for example, titanium oxide, zinc white, zinc sulfide, lead white, calcium carbonate, precipitated barium sulfate, silica white, aluminum oxide white, kaolin, talc, bentonite, black iron oxide, cadmium red, iron oxide red, molybdenum red, molybdenum orange, chrome vermilion, lead yellow, cadmium yellow, iron oxide yellow, titanium yellow, chromium oxide, chromium green (viridian), titanium cobalt green, cobalt green, cobalt chromium green, victoria green, ultramarine, prussian blue, cobalt blue, cerulean blue (also known as "azure"), cobalt silicon blue, cobalt zinc silicon blue, manganese violet, cobalt violet, etc. can be mentioned.

[0033] As the content of the above pigment, it is preferably 1% by mass to 20% by mass, more preferably 3% by mass to 10% by mass, based on the total mass of the aqueous inkjet ink in terms of solid content.

[0034] (Resin fine particles)

[0035] The aqueous inkjet ink of the present invention contains resin fine particles.

[0036] Examples of the above resin fine particles include: Resin fine particles such as polyethylene resin, polypropylene resin, polyurethane 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-acrylate copolymer resin, fluoroolefin resin, polyester polyurethane resin, polyether polyurethane resin, polycarbonate polyurethane resin, and polyester resin.

[0037] As the above resin fine particles, from the viewpoint of appropriately imparting abrasion resistance, it is 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-acrylate copolymer resin, polyester polyurethane resin, polyether polyurethane resin, polycarbonate polyurethane resin, and polyester resin, and more preferably at least one selected from the group consisting of polyethylene resin, styrene-acrylic copolymer resin, polyester polyurethane resin, and polyether polyurethane resin.

[0038] The above resin fine particles may be composed of one resin or two or more resins.

[0039] As the volume average particle diameter of the above resin fine particles, for example, it is preferably 10 nm to 1000 nm, more preferably 30 nm to 500 nm, and further preferably 50 nm to 300 nm.

[0040] It should be noted that the volume average particle diameter can be obtained using a particle size distribution measuring device, for example.

[0041] As the content of the above resin fine particles, it is 0.5% by mass to 10% by mass based on the total mass of the aqueous inkjet ink in terms of solid content.

[0042] If the content of the resin fine particles is less than 0.5% by mass based on the total mass of the aqueous inkjet ink in terms of solid content, the abrasion resistance is insufficient; if it exceeds 10% by mass in terms of solid content, the ejection property and continuous ejection property are insufficient.

[0043] From the viewpoint of appropriately imparting storage stability, the content of the above resin particles is preferably 1% by mass or more based on the total mass of the aqueous inkjet ink in terms of solid content.

[0044] In addition, from the viewpoint of appropriately imparting abrasion resistance, it is preferably 8% by mass or less, more preferably 5% by mass or less based on the total mass of the aqueous inkjet ink in terms of solid content.

[0045] (Surfactant)

[0046] The aqueous inkjet ink of the present invention contains a surfactant represented by the following general formula (I) as a surfactant.

[0047]

[0048] In the general formula (I), R 1 is a linear or branched substituent having 1 to 15 carbon atoms and containing a hydroxyl group and / or an ether structure.

[0049] In the above general formula (I), from the viewpoint of appropriately imparting storage stability to the aqueous inkjet ink, R 1 preferably contains a hydroxyl group, and more preferably contains a hydroxyl group and an ether structure.

[0050] In the above general formula (I), from the viewpoint of appropriately improving the storage stability and refillability of the aqueous inkjet ink, R 1 preferably has 2 to 11 carbon atoms, and more preferably has 4 to 11 carbon atoms.

[0051] Specific examples of the surfactant represented by the above general formula (I) include: 2-{[2-hydroxy-3-(octyloxy)propyl]thio}ethanol, 2,2'-thiodiethanol, 1-[(2-hydroxyethyl)thio]-2-propanol, etc.

[0052] Among them, from the viewpoint of appropriately improving storage stability and refillability, 2-{[2-hydroxy-3-(octyloxy)propyl]thio}ethanol is preferred.

[0053] The aqueous inkjet ink of the present invention contains 0.01% by mass to 1% by mass of the surfactant represented by the above general formula (I) based on the total mass of the aqueous inkjet ink.

[0054] When the content of the surfactant represented by the above general formula (I) is less than 0.01% by mass, the continuous ejection property and abrasion resistance decrease; when the content exceeds 1% by mass, the storage stability, ejection property, continuous ejection property, and abrasion resistance decrease.

[0055] From the viewpoint of appropriately imparting continuous ejection properties, it is preferable that the surfactant represented by the above general formula (I) is 0.1% by mass or more based on the total mass of the aqueous inkjet ink. Further, from the viewpoints of appropriately imparting storage stability and ejection properties, it is preferably 0.8% by mass or less, more preferably 0.6% by mass or less, and still more preferably 0.5% by mass or less based on the total mass of the aqueous inkjet ink in terms of solid content.

[0056] From the viewpoint of further improving ejection properties, the aqueous inkjet ink of the present invention preferably further contains a nonionic surfactant and / or an anionic surfactant.

[0057] Examples of the nonionic surfactant include polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkyl ethers, polyoxyethylene alkyl amines, polyoxyethylene alkyl amides, polyoxyethylene-polypropylene block copolymers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyether siloxane copolymers, ethylene oxide adducts of acetylene alcohols, and the like.

[0058] Examples of the anionic surfactant include polyoxyethylene alkyl ether acetates, dodecylbenzenesulfonates, laurates, sodium sulfate esters, salts of polyoxyethylene alkyl ether sulfates, and the like.

[0059] The content of the nonionic surfactant and / or anionic surfactant is preferably 0.1% by mass to 1% by mass.

[0060] The nonionic surfactant and / or anionic surfactant may be used alone or in combination of two or more.

[0061] (Water)

[0062] The aqueous inkjet ink of the present invention contains water.

[0063] From the viewpoints of appropriately imparting ejection properties and storage stability, the content of water is preferably 15% by mass to 70% by mass based on the total mass of the aqueous inkjet ink.

[0064] (Water-soluble solvent)

[0065] The aqueous inkjet ink of the present invention may contain a water-soluble solvent.

[0066] The water-soluble solvent is not particularly limited, and examples thereof include monohydric alcohols, trihydric alcohols, dihydric alcohols, polyhydric alcohols having four or more hydroxyl groups, lower alkyl ethers of polyhydric alcohols, ketones, ethers, esters, nitrogen-containing compounds, and the like. These may be used alone or in combination of two or more.

[0067] From the viewpoint of appropriately imparting ejection properties and storage stability, the content of the above-mentioned water-soluble solvent is preferably 15% by mass to 70% by mass relative to the total mass of the aqueous inkjet ink.

[0068] (Pigment dispersant)

[0069] The aqueous inkjet ink of the present invention may contain a pigment dispersant.

[0070] Examples of the above-mentioned pigment dispersant include carbodiimide dispersants, polyesteramine dispersants, fatty acid amine dispersants, modified polyacrylate dispersants, modified polyurethane dispersants, multi-chain polymer nonionic dispersants, and polymer surfactants.

[0071] These pigment dispersants can be used alone or in combination of two or more.

[0072] As the above-mentioned pigment dispersant, a copolymer of styrene, (meth)acrylic acid alkyl ester, and (meth)acrylic acid is more preferably used, and a copolymer of (meth)acrylic acid and stearyl (meth)acrylate, or a copolymer of styrene and lauryl (meth)acrylate is further preferably used. Particularly preferably, it is a copolymer of (meth)acrylic acid, stearyl (meth)acrylate, and styrene.

[0073] It should be noted that the so-called (meth)acrylate refers to acrylate and / or methacrylate, and the so-called (meth)acrylic acid refers to acrylic acid and / or methacrylic acid.

[0074] As the content of the above-mentioned pigment dispersant, relative to 100 parts by mass of the above-mentioned pigment, it is preferably 1 to 200 parts by mass, and more preferably 5 to 100 parts by mass.

[0075] (Other additives)

[0076] The aqueous inkjet ink of the present invention may contain various additives such as ultraviolet absorbers, antioxidants, defoamers, storage improvers, fungicides, rust inhibitors, thickeners, humectants, and pH adjusters as needed.

[0077] As the content of the above-mentioned additives, for example, in terms of solid content, it is about 0% by mass to 10% by mass relative to the total mass of the aqueous inkjet ink.

[0078] (Manufacturing method of aqueous inkjet ink)

[0079] The manufacturing method of the aqueous inkjet ink of the present invention is not particularly limited. For example, the above-mentioned components can be added sequentially or simultaneously, followed by mixing, stirring, and grinding treatment (homogenization treatment).

[0080] When successively mixing and stirring the above-mentioned components, for example, an aqueous pigment ink base can be prepared by mixing and stirring pigments after mixing a pigment dispersant with water or a water-soluble solvent to obtain an aqueous resin varnish, and then mixing and stirring with resin particles, a surfactant, and water or a water-soluble solvent as required, followed by grinding treatment, thereby preparing an aqueous inkjet ink.

[0081] There is no particular limitation on the method for the above mixing, stirring, and grinding treatment. For example, a bead mill, a Ready mill (also known as a "preparation mill"), an ultrasonic homogenizer, a high-pressure homogenizer, a paint shaker, a ball mill, a roll mill, a sand mill, a sand grinder, a DYNO mill, a high-speed disperser (DISPERMAT), an SC mill, a high-pressure homogenizer (Nanomizer), etc. can be used, and the mixing, stirring, and grinding treatment (homogenization treatment) can be carried out by well-known methods.

[0082] (Properties of Aqueous Inkjet Ink)

[0083] The aqueous inkjet ink of the present invention preferably has excellent storage stability.

[0084] The storage stability can be evaluated by the following method.

[0085] Fill the aqueous inkjet ink into a glass bottle, and use a viscometer (RE100L type, manufactured by Toki Sangyo Co., Ltd.) to measure its viscosity at 25 °C.

[0086] Then, seal the bottle with a stopper and store it at 60 °C for one month, and use the above viscometer to measure the viscosity after storage (25 °C).

[0087] The storage stability is evaluated according to the viscosity change rate [at 60 °C (viscosity after one month - viscosity before storage) / viscosity before storage].

[0088] If the above viscosity change rate is less than 10%, it can be evaluated that the storage stability is excellent; if the above viscosity change rate is less than 5%, it can be evaluated that the storage stability is extremely excellent.

[0089] The aqueous inkjet ink of the present invention has excellent ejectability.

[0090] The ejectability can be evaluated by the following method.

[0091] Fill the aqueous inkjet ink into the ink cartridge of a printer PX105 manufactured by Seiko Epson Corporation for graphic printing (printing), and evaluate its ejectability.

[0092] Even if there are some misalignments in the graphic printing, as long as it can be ejected, it is evaluated as having excellent ejection performance; if there is no misalignment in the graphic printing and it can be stably ejected, it can be evaluated as having extremely excellent ejection performance.

[0093] It should be noted that when the water-based inkjet ink is black, cyan, magenta or yellow, photo paper GL-101A450 (manufactured by Canon Inc.) is used for graphic printing; when the water-based inkjet ink is white, light-shielding paper is used for graphic printing.

[0094] The water-based inkjet ink of the present invention has excellent continuous ejection performance.

[0095] The continuous ejection performance can be evaluated by the following method.

[0096] The water-based inkjet ink is filled into the ink cartridge of printer PX105 manufactured by Epson, and 50 solid images of 15 cm × 20 cm are continuously printed to evaluate its continuous ejection performance.

[0097] If the image quality of the printed matter obtained by the above printing is good and the water-based inkjet ink can be stably ejected, it can be evaluated as having excellent continuous ejection performance.

[0098] It should be noted that when the water-based inkjet ink is black, cyan, magenta or yellow, printing is carried out on photo paper GL-101A450 (manufactured by Canon Inc.); when the water-based inkjet ink is white, printing is carried out on light-shielding paper.

[0099] The water-based inkjet ink of the present invention has excellent abrasion resistance.

[0100] The abrasion resistance can be evaluated by the following method.

[0101] The printed matter obtained by the above continuous ejection performance evaluation is dried in an oven at 80 for 3 minutes, and then the printed surface is wiped with a cotton swab to evaluate the abrasion resistance.

[0102] If the color transfers to the cotton swab after rubbing the printed surface 10 times with the cotton swab and there is a slight scratch (white streaks) at the wiped part, it can be evaluated as having excellent abrasion resistance; if there is no scratch at all after rubbing the printed surface 10 times with the cotton swab, it can be evaluated as having extremely excellent abrasion resistance.

[0103] Embodiment

[0104] Hereinafter, the present invention will be specifically described by using examples. However, the present invention is not limited thereto without departing from its gist and application scope. It should be noted that in this embodiment, "parts" and "%" respectively represent "parts by mass" and "% by mass" without special description.

[0105] <Preparation of Aqueous Dye Ink Base>

[0106] (Aqueous Resin Varnish)

[0107] 30 parts by mass of an acrylic / acrylic stearate / styrene copolymer was dissolved in a mixed solution of 3.8 parts by mass of potassium hydroxide and 66.2 parts by mass of water to prepare an aqueous resin varnish with a solid content of 30% by mass.

[0108] (Preparation of Aqueous Black Ink Base)

[0109] 48 parts by mass of water was added to 32 parts by mass of the above aqueous resin varnish and mixed to prepare a resin varnish for pigment dispersion.

[0110] 20 parts by mass of carbon black (trade name: Printex 90, manufactured by Degussa) was added to the above resin varnish for pigment dispersion. After stirring and mixing, it was ground (homogenized) with a wet circulation mill to prepare an aqueous black ink base (pigment ratio = 20% by mass).

[0111] (Aqueous Cyan Ink Base)

[0112] 48 parts by mass of water was added to 32 parts by mass of the above aqueous resin varnish and mixed to prepare a resin varnish for pigment dispersion.

[0113] 20 parts by mass of a cyan pigment (trade name: Heliogen Blue L7101F, manufactured by BASF) was added to the above resin varnish for pigment dispersion. After stirring and mixing, it was ground with a wet circulation mill to prepare an aqueous cyan ink base (pigment ratio = 20% by mass).

[0114] (Preparation of Aqueous Magenta Ink Base)

[0115] 48 parts by mass of water was added to 32 parts by mass of the above aqueous resin varnish and mixed to prepare a resin varnish for pigment dispersion.

[0116] 20 parts by mass of a magenta pigment (trade name: Ink Jet Magenta E5B02, manufactured by Clariant Company) was added to the above resin varnish for pigment dispersion. After stirring and mixing, it was ground with a wet circulation mill to prepare an aqueous magenta ink base (pigment ratio = 20% by mass).

[0117] (aqueous yellow ink base)

[0118] 48 parts by mass of water was added to 32 parts by mass of the above aqueous resin varnish and mixed to prepare a resin varnish for pigment dispersion.

[0119] 20 parts by mass of a yellow pigment (trade name: Novoperm Yellow 4G01, manufactured by Clariant Company) was added to the above resin varnish for pigment dispersion. After stirring and mixing, it was ground with a wet circulation mill to prepare an aqueous yellow ink base (pigment ratio = 20% by mass).

[0120] (aqueous white ink base)

[0121] 28 parts by mass of water was added to 32 parts by mass of the above aqueous resin varnish and mixed to prepare a resin varnish for pigment dispersion.

[0122] 40 parts by mass of titanium oxide pigment (trade name: CR - 90, manufactured by Ishihara Sangyo Co., Ltd.) was added to the above resin varnish for pigment dispersion. After stirring and mixing, it was ground (homogenized) with a wet circulation mill to prepare an aqueous white ink base (pigment ratio = 40% by mass).

[0123] The various materials used in the following examples and comparative examples are described below.

[0124] <Resin Particles>

[0125] Polyethylene resin particles (trade name: AQUACER 531, manufactured by BYK Company)

[0126] Acrylic resin particles (trade name: YODOSOL AD173, manufactured by HENKEL Company)

[0127] Styrene - acrylic copolymer resin particles (trade name: NeoCryl A - 1092, manufactured by Covestro Company)

[0128] Vinyl acetate - acrylic copolymer resin particles (trade name: VINYBLAN 1245L, manufactured by Nissin Chemical Industry Co., Ltd.)

[0129] Vinyl chloride - acrylate copolymer resin particles (trade name: VINYBLAN 278, manufactured by Nissin Chemical Industry Co., Ltd.)

[0130] Vinyl acetate resin particles (trade name: VINYBLAN GV6181, manufactured by Nissin Chemical Industry Co., Ltd.)

[0131] Polyester polyurethane resin particles (trade name: SUPERFLEX 740, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)

[0132] Polyether polyurethane resin particles (trade name: NeoRez R-966, manufactured by Covestro)

[0133] Polycarbonate polyurethane resin particles (trade name: SUPERFLEX 420NS, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)

[0134] Polyester resin particles (trade name: SEPOLSION ES, manufactured by Sumitomo Seika Chemicals Co., Ltd.)

[0135] <Surfactant>

[0136] (Surfactant satisfying the above general formula (I))

[0137] 2-{[2-Hydroxy-3-(octyloxy)propyl]thio}ethan-1-ol

[0138] 2,2'-Thiodiethanol

[0139] 1-[(2-Hydroxyethyl)thio]-2-propanol

[0140] (Surfactant not satisfying the above general formula (I))

[0141] 2-(Methylthio)ethanol

[0142] 2-(Ethylthio)ethanol

[0143] 2-(Isopropylthio)ethanol

[0144] 2-(Isobutylthio)ethanol

[0145] 2-(n-Propylthio)ethanol

[0146] (Nonionic surfactant)

[0147] Nonionic surfactant A (trade name: SURFYNOL 465, manufactured by Nissin Chemical Industry Co., Ltd.)

[0148] Nonionic surfactant B (trade name: EMULGEN 705, manufactured by Kao Corporation)

[0149] Nonionic surfactant C (trade name: TEGO Glide 450, manufactured by Evonik)

[0150] (Anionic surfactant)

[0151] Anionic surfactant (trade name: PERSOFT EF, manufactured by ADEKA Corporation)

[0152] <Water-soluble solvent>

[0153] Propylene glycol

[0154] Glycerol

[0155] <Water>

[0156] Purified water

[0157] (Examples 1 to 25, Comparative Examples 1 to 8)

[0158] Mix and stir each material according to the compounding amounts described in Tables 1, 2, and 3 to obtain an aqueous inkjet ink.

[0159] <Storage stability>

[0160] Put the obtained aqueous inkjet ink into a glass bottle, and use a viscometer (RE100L type, manufactured by Toki Sangyo Co., Ltd.) to measure its viscosity at 25 degrees Celsius.

[0161] Then, add a sealing plug and store it at 60 degrees Celsius for one month, and use the above viscometer to measure the viscosity after storage (25 degrees Celsius).

[0162] The storage stability is evaluated according to the viscosity change rate [at 60 (viscosity after one month - viscosity before storage) / viscosity before storage] according to the following criteria.

[0163] (Evaluation criteria)

[0164] ◎: The viscosity change rate is less than 5%; ○: The viscosity change rate is 5% or more and less than 10%; ×: The viscosity change rate is 10% or more.

[0165] <Sprayability>

[0166] Put the obtained aqueous inkjet ink into the ink cartridge of printer PX105 manufactured by Epson for graphic printing, and evaluate the sprayability according to the following evaluation criteria.

[0167] Note that when the aqueous inkjet ink is black, cyan, magenta, or yellow, use photo paper GL-101A450 (manufactured by Canon) for graphic printing; when the aqueous inkjet ink is white, use light-shielding paper for graphic printing.

[0168] (Evaluation criteria)

[0169] ◎: The graphic printing is not disordered and can be stably sprayed; 〇: Although there is somewhat disorder in the graphic printing, it can be ejected; ×: The graphic printing is disordered and stable ejection cannot be achieved.

[0170] <Continuity of ejection>

[0171] The prepared water-based inkjet ink was filled into the ink cartridge of the printer PX105 manufactured by Seiko Epson Corporation, and 50 solid images of 15 cm × 20 cm were continuously printed, and its continuity of ejection was evaluated according to the following evaluation criteria.

[0172] It should be noted that when the water-based inkjet ink is black, cyan, magenta or yellow, printing is performed on photo paper GL-101A450 (manufactured by Canon Inc.); when the water-based inkjet ink is white, printing is performed on light-shielding paper.

[0173] (Evaluation criteria)

[0174] 〇: The image quality of the printed matter obtained by printing is good and stable ejection can be achieved; ×: Deterioration of image quality such as stripes is found in the printed matter obtained by printing, and stable ejection cannot be achieved.

[0175] <Scratch resistance>

[0176] The printed matter obtained by the above evaluation of continuity of ejection was dried in an oven at 80 for 3 minutes, and then the printed surface was wiped with a cotton swab and the scratch resistance was evaluated according to the following evaluation criteria.

[0177] (Evaluation criteria)

[0178] ◎: There are no scratches (white streaks) at all even after rubbing the printed surface with a cotton swab 10 times; 〇: After rubbing the printed surface with a cotton swab 10 times, the color is transferred to the cotton swab and there are slightly scratches on the rubbed part; △: After rubbing the printed surface with a cotton swab 10 times, a part of the rubbed part falls off; ×: After rubbing the printed surface with a cotton swab 10 times, the entire rubbed part falls off.

[0179] [Table 1]

[0180] [Table 2]

[0181] [Table 3]

[0182] It can be confirmed from the examples that in an aqueous inkjet ink containing a pigment, resin particles, a surfactant, and water, by setting the content of the resin particles within a specified range and using a specific surfactant, a coating film excellent in storage stability, ejection property, continuous ejection property, and abrasion resistance can be formed.

[0183] In particular, in the example where 2-{[2-hydroxy-3-(octyloxy)propyl]sulfanyl}ethanol is used as the surfactant represented by the general formula (I) above, the ejection property is extremely excellent.

[0184] In addition, in the examples where polyethylene resin particles, styrene-acrylic copolymer resin particles, polyester polyurethane resin particles, or polyether polyurethane resin particles are used as the resin particles, the abrasion resistance is extremely excellent.

[0185] On the other hand, in the comparative examples, a coating film excellent in ejection property, continuous ejection property, and abrasion resistance could not be formed.

[0186] In addition, in Comparative Examples 2 to 8, in the evaluation of the continuous ejection property, since no printed matter could be obtained, the evaluation of the abrasion resistance could not be performed (marked as "-" in Table 3).

[0187] The following technical solutions are disclosed in this specification.

[0188] The present disclosure (1) is an aqueous inkjet ink containing a pigment, resin particles, a surfactant, and water, wherein the content of the resin particles is 0.5% by mass to 10% by mass based on the total mass of the aqueous inkjet ink in terms of solid content; as the surfactant, it contains a surfactant represented by the following general formula (I) in an amount of 0.01% by mass to 1% by mass based on the total mass of the aqueous inkjet ink.

[0189]

[0190] In the general formula (I), R 1 is a linear or branched substituent having 1 to 15 carbon atoms and containing a hydroxyl group and / or an ether structure.

[0191] The present disclosure (2) is the aqueous inkjet ink according to the present disclosure (1), wherein in the general formula (I) above, R 1 contains a hydroxyl group.

[0192] The present disclosure (3) is the aqueous inkjet ink according to the present disclosure (1) or (2), wherein in the general formula (I) above, R 1 contains a hydroxyl group and an ether structure.

[0193] The present disclosure (4) is the aqueous inkjet ink according to any one of the present disclosures (1) to (3), wherein in the general formula (I) above, R1 has 2 to 11 carbon atoms.

[0194] The present disclosure (5) is an aqueous inkjet ink according to any one of the present disclosures (1) to (4), wherein the surfactant further contains a nonionic surfactant and / or an anionic surfactant.

[0195] The present disclosure (6) is an aqueous inkjet ink according to any one of the present disclosures (1) to (5), wherein the content of the surfactant represented by the general formula (I) is 0.1% by mass to 0.5% by mass relative to the total mass of the aqueous inkjet ink; The present disclosure (7) is an aqueous inkjet ink according to any one of the present disclosures (1) to (6), wherein the resin particles are at least one selected from the group consisting of a polyethylene resin, an acrylic resin, a styrene-acrylic copolymer resin, a vinyl acetate-acrylic copolymer resin, a vinyl chloride-acrylate copolymer resin, a vinyl acetate resin, a polyester polyurethane resin, a polyether polyurethane resin, a polycarbonate polyurethane resin, and a polyester resin.

[0196] The present disclosure (8) is an aqueous inkjet ink according to any one of the present disclosures (1) to (7), wherein the content of the resin particles is 1% by mass to 5% by mass relative to the total mass of the aqueous inkjet ink in terms of solid content.

[0197] Industrial Applicability

[0198] Based on the present invention, an aqueous inkjet ink having excellent ejection properties, continuous ejection properties, and capable of forming a film with excellent abrasion resistance can be provided.

Claims

1. An aqueous inkjet ink, which comprises a pigment, resin particles, a surfactant, and water, wherein, the content of the resin particles is 0.5% by mass to 10% by mass based on the total mass of the aqueous inkjet ink in terms of solid content; as the surfactant, it contains a surfactant represented by the following general formula (I) in an amount of 0.01% by mass to 1% by mass based on the total mass of the aqueous inkjet ink, In general formula (I), R 1 is a linear or branched substituent having 1 to 15 carbon atoms and containing a hydroxyl group and / or an ether structure.

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

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

4. The water-based inkjet ink according to claim 1 or 2, wherein, In the general formula (I), R 1 has 2 to 11 carbon atoms.

5. The aqueous inkjet ink according to claim 1 or 2, wherein as the surfactant, it further contains a nonionic surfactant and / or an anionic 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% by mass to 0.5% by mass based on the total mass of the aqueous inkjet ink.

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

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

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