Ink set and inkjet recording method

Abstract

This provides an ink set capable of recording flexible images with excellent tensile strength. [Solution] An inkjet ink set comprising an aqueous ink containing a colorant and a liquid composition containing resin particles. The resin forming the resin particles is a copolymer having at least one unit selected from the group consisting of a unit derived from a monomer represented by the following general formula (1) and a unit derived from a monomer represented by the following general formula (2). TIFF2026141986000029.tif35170

Description

[Technical Field]

[0001] The present invention relates to an ink set and an inkjet recording method. [Background Art]

[0002] Conventionally, inkjet recording apparatuses have been widely used as small-sized printers for home use. In recent years, inkjet recording apparatuses have come to be deployed also in fields such as office use, commercial printing, and industrial printing. Inkjet recording apparatuses used in such fields are required to be capable of recording images having higher image performance. For example, when vehicles such as automobiles and trains are temporarily modified for advertising purposes, recording may be performed on a recording medium such as a film, and the vehicle surface is covered with the recorded matter. When wrapping a vehicle with the recorded matter, the recorded matter is attached while being stretched, so the recorded matter is required to have good tensile resistance as an image performance.

[0003] On the other hand, Patent Document 1 proposes an aqueous ink containing self-dispersing polymer particles including a hydrophilic constitutional unit and a hydrophobic constitutional unit derived from an alicyclic (meth)acrylate, as an aqueous ink capable of recording an image with good fixability and blocking resistance. [Prior Art Literature] [Patent Literature]

[0004] [Patent Document 1] Japanese Patent Laid-Open No. 2010-077218 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] By using the conventional water-based ink proposed in Patent Document 1, it is possible to record images with good fixability and blocking resistance. On the other hand, it has been found that when an image is recorded on a flexible recording medium such as a resin film or packaging paper made of polyethylene terephthalate (PET) and then the recording is pulled, the image recorded on the recording medium tears to the point where the underlying material of the recording medium is visible.

[0006] Therefore, an object of the present invention is to provide an ink set capable of recording flexible images with excellent tensile strength. Another object of the present invention is to provide an inkjet recording method using the above ink set. [Means for solving the problem]

[0007] In other words, the present invention provides an inkjet ink set comprising an aqueous ink containing a colorant and a liquid composition having resin particles, wherein the resin forming the resin particles is a copolymer having at least one unit selected from the group consisting of a unit derived from a monomer represented by the following general formula (1) and a unit derived from a monomer represented by the following general formula (2).

[0008] TIFF2026141986000001.tif33170(In the above general formula (1), R 1 R represents a hydrogen atom or a methyl group. 2 (where 'NH represents an oxygen atom, 'X' represents a methylene group, and 'm' represents an integer from 1 to 6.)

[0009] TIFF2026141986000002.tif12170 (In the above general formula (2), Y represents an oxyalkylene group having 2 to 4 carbon atoms, and n represents an integer from 1 to 3.) [Effects of the Invention]

[0010] According to the present invention, it is possible to provide an ink set capable of recording flexible images with excellent tensile strength. Furthermore, according to the present invention, it is possible to provide an inkjet recording method using the above ink set. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic cross-sectional view showing one embodiment of the ink cartridge of the present invention. [Figure 2] This figure schematically shows an example of an inkjet recording apparatus used in the inkjet recording method of the present invention, where (a) is a perspective view of the main part of the inkjet recording apparatus and (b) is a perspective view of the head cartridge. [Modes for carrying out the invention]

[0012] The present invention will be described in more detail below with reference to preferred embodiments. In the present invention, when a compound is a salt, the salt exists in the ink dissociated into ions, but for convenience, it will be expressed as "contains a salt." Also, water-based inkjet ink may be simply referred to as "ink." Unless otherwise specified, physical properties are given at room temperature (25°C), normal pressure (1 atmosphere = 101,325 Pa), and normal humidity (50% relative humidity). Furthermore, with respect to resins, "unit" means the unit structure corresponding to one monomer unless otherwise specified. When "(meth)acrylic acid" or "(meth)acrylate" is written, it means "acrylic acid, methacrylic acid" and "acrylate, methacrylate," respectively.

[0013] The present inventors investigated liquid compositions to be used with aqueous ink in order to obtain an ink set capable of recording images with excellent tensile strength. As a result, they found that by using an inkjet ink set comprising an aqueous ink containing a colorant and a liquid composition containing resin particles formed of a specific resin, it is possible to record images with excellent tensile strength. The specific resin is a copolymer having at least one unit selected from the group consisting of a unit derived from a monomer represented by the following general formula (1) and a unit derived from a monomer represented by the following general formula (2).

[0014] TIFF2026141986000003.tif33170(In general formula (1), R 1 R represents a hydrogen atom or a methyl group. 2 (where 'NH represents an oxygen atom, 'X' represents a methylene group, and 'm' represents an integer from 1 to 6.)

[0015] TIFF2026141986000004.tif12170 (In general formula (2), Y represents an oxyalkylene group having 2 to 4 carbon atoms, and n represents an integer from 1 to 3.)

[0016] The inventors speculate that the mechanism by which the above ink set enables the recording of images with excellent tensile strength is as follows:

[0017] The resin that forms the resin particles to be contained in the liquid composition is a copolymer having at least one unit selected from the group consisting of a unit derived from a monomer represented by general formula (1) and a unit derived from a monomer represented by general formula (2). Both the unit derived from the monomer represented by general formula (1) and the unit derived from the monomer represented by general formula (2) have a hydroxyl group. Furthermore, the unit derived from the monomer represented by general formula (1) also has an ester bond or an amide bond.

[0018] As mentioned above, the resin that forms the resin particles has hydroxyl groups. Therefore, it is presumed that the resin particles form hydrogen bonds with each other in the liquid composition, and while maintaining these hydrogen bonds, they are fixed to the recording medium, and the volatile components in the liquid composition evaporate, causing the liquid composition to form a film, thus resulting in an image with excellent tensile strength.

[0019] Generally, the colorants used in water-based inks include pigments containing dispersants, self-dispersing pigments having hydrophilic groups such as carboxylic acid groups on the surface of the pigment particles, and dyes having hydrophilic groups, all of which are stable in water. When resin particles having the aforementioned hydroxyl groups are added to an ink containing such colorants, the hydrogen-bonding elements of the colorant components (e.g., oxygen and nitrogen) inhibit the formation of hydrogen bonds between the resin particles, making it impossible to obtain sufficient tensile strength.

[0020] Furthermore, in order to obtain images with excellent tensile strength, it is important that rearrangement of intermolecular interactions within the film in which the image is formed occurs, that is, rearrangement of hydrogen bonds. To achieve this, it is necessary to use resin particles having the aforementioned hydroxyl groups. In the case of resin particles formed from a resin that does not have hydroxyl groups but has units derived from monomers having acidic groups such as carboxylic acid groups, sulfonic acid groups, and phosphate groups, ionic bonds due to the acidic groups between the resin particles become dominant, and weak hydrogen bonds are less likely to occur. In contrast, resin particles formed from a resin having units derived from monomers having hydroxyl groups have many sites on the surface of the resin particles where hydrogen bonding can occur, so hydrogen bonds are easily formed between the resin particles.

[0021] By using resin particles that induce rearrangement of hydrogen bonds, an interaction network based on hydrogen bonds is created within the recorded image. Since hydrogen bonds are weaker than ionic or covalent bonds in terms of bonding strength, they are thought to be easily broken when the recorded material is pulled. However, even if hydrogen bonds are broken, it is hypothesized that new hydrogen bonds can be formed with other hydroxyl groups, ester bonds, or amide bonds, making the image less likely to tear when the recorded material is pulled, resulting in an image with excellent tensile strength.

[0022] In order for the above-mentioned hydrogen bond rearrangement to occur, m in general formula (1) must be an integer between 1 and 6. If m in general formula (1) is 0, not only will the structure become unstable, but as mentioned above, the interaction between resin particles will not function sufficiently, and it will not be possible to obtain an image with excellent tensile strength. On the other hand, if m in general formula (1) is 7 or more, the carbon chain in X in general formula (1) will be too long, making it difficult for the above-mentioned hydrogen bond rearrangement to occur, and it will not be possible to obtain an image with excellent tensile strength.

[0023] Furthermore, in general formula (2), Y must represent an oxyalkylene group having 2 to 4 carbon atoms, and n must represent an integer from 1 to 3. Here, the oxygen atom of the oxyalkylene group is bonded to the vinyl group, and the carbon atom of the oxyalkylene group is bonded to OH. If n in general formula (2) is 4 or more, the above-mentioned hydrogen bond rearrangement is less likely to occur, and an image with excellent tensile strength cannot be obtained. Also, if the number of carbon atoms in Y in general formula (2) is 1 or 5 or more, the carbon chain is too short or too long, so the above-mentioned hydrogen bond rearrangement is less likely to occur, and an image with excellent tensile strength cannot be obtained.

[0024] <Ink Set> The present invention provides an inkjet ink set comprising an aqueous ink containing a colorant and a liquid composition containing specific resin particles. This ink set may contain one of the aqueous inks alone or two or more of them, and may also contain one of the liquid compositions alone or two or more of them.

[0025] In this disclosure, "resin particles" means a resin that is dispersed in an aqueous medium and can exist in the aqueous medium in a state having a particle size. Resin particles are resins that do not dissolve in the aqueous medium that constitutes an aqueous dispersion or liquid composition of resin particles, and specifically, are resins that can exist in an aqueous medium in a state in which particles whose particle size can be measured by dynamic light scattering are formed. When expressing resin particles in contrast to "water-soluble resins," they are expressed as "water-dispersible resins (water-insoluble resins)."

[0026] Whether a resin is a "resin particle" or not can be determined according to the following method. First, prepare a liquid containing the resin to be judged (resin content: 10% by mass). Next, prepare a sample by diluting the prepared liquid 10 times (by volume) with pure water. Then, measure the particle size of the resin in the sample using dynamic light scattering. If particles with a particle size are measured, the resin is determined to be a "resin particle" (i.e., a "water-dispersible resin"). On the other hand, if particles with a particle size are not measured, the resin is determined not to be a "resin particle" (i.e., a "water-soluble resin"). The measurement conditions in this case can be, for example, SetZero: 30 seconds, Number of measurements: 10 times, Measurement time: 120 seconds, Shape: Spherical, Refractive index: 1.5, Density: 1.0. As a particle size distribution analyzer, a particle size analyzer using dynamic light scattering (for example, product name "NanoTrac WAVE II-Q", manufactured by MicroTrac-Bell) can be used. Of course, the particle size analyzer and measurement conditions are not limited to those described above.

[0027] [Liquid composition] The liquid composition contains specific resin particles. The resin forming these resin particles is a copolymer having at least one unit selected from the group consisting of a unit derived from a monomer represented by the following general formula (1) and a unit derived from a monomer represented by the following general formula (2).

[0028] TIFF2026141986000005.tif33170(In general formula (1), R 1 R represents a hydrogen atom or a methyl group. 2represents NH or an oxygen atom, X represents a methylene group, and m represents an integer of 1 to 6.)

[0029] TIFF2026141986000006.tif12170(In general formula (2), Y represents an oxyalkylene group having 2 to 4 carbon atoms, and n represents an integer of 1 to 3.)

[0030] The methylene group represented by X in general formula (1) is a divalent group obtained by removing two hydrogen atoms from methane. m in general formula (1) is an integer of 1 to 6, preferably an integer of 1 to 3. -(X) m Examples of the functional group represented by - include a methylene group, an ethylene group, a trimethylene group, a propylene group (* 1 -(CH2CH(CH3)) m -* 2 , * 1 -(CH(CH3)CH2) m -* 2 ;* 1 represents a bond to R in general formula (1), * 2 represents a bond to R in general formula (1), * 2 represents a bond to OH in general formula (1)), examples thereof include a tetramethylene group, a pentamethylene group, and a hexamethylene group. Further, as the monomer represented by general formula (1), a monomer in which m in general formula (1) is 1 or 2 is more preferable.

[0031] R 2 Examples of the monomer represented by general formula (1) in which is NH include N-(hydroxymethyl)acrylamide, N-(hydroxymethyl)methacrylamide, N-(2-hydroxyethyl)acrylamide, N-(2-hydroxyethyl)methacrylamide, N-(2-hydroxypropyl)acrylamide, N-(2-hydroxypropyl)methacrylamide, N-(3-hydroxypropyl)acrylamide, and N-(3-hydroxypropyl)methacrylamide. One or two or more of these can be used.

[0032] R 2Examples of monomers represented by general formula (1), in which the atom is an oxygen atom, include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate. One or more of these can be used.

[0033] -(Y) in general formula (2) n - The 1 to 3 oxyalkylene groups represented by - are * 3 -(OC2H4) n -* 4 , * 3 -(OC3H6) n -* 4 , and * 3 -(OC4H8) n -* 4 These are divalent groups represented by * 3 * represents the bond with the vinyl group in general formula (2), 4 represents the bond with OH in general formula (2), and n is an integer from 1 to 3.

[0034] Examples of monomers represented by general formula (2) include ethylene glycol monovinyl ether, propylene glycol monovinyl ether, diethylene glycol monovinyl ether, triethylene glycol monovinyl ether, trimethylene glycol monovinyl ether, and tetramethylene glycol monovinyl ether. One or more of these can be used.

[0035] In particular, the resin forming the resin particles more preferably has units derived from monomers represented by general formula (1) or (2), specifically units derived from at least one monomer selected from the group consisting of 2-hydroxyethyl methacrylate, N-(hydroxymethyl)methacrylamide, ethylene glycol monovinyl ether, and diethylene glycol monovinyl ether.

[0036] Furthermore, the resin forming the resin particles is a copolymer having units derived from a monomer represented by general formula (1), and a copolymer in which the monomer represented by general formula (1) contains 2-hydroxyethyl methacrylate is even more preferable. By having units derived from 2-hydroxyethyl methacrylate in the resin forming the resin particles, images with even better tensile strength can be obtained. The ratio of hydroxyl groups to molecular weight of 2-hydroxyethyl methacrylate is an optimal molecular size for the formation of hydrogen bonds after the aforementioned cleavage, and it is thought that the tensile strength of the images is likely to be further improved.

[0037] The total percentage (mass%) of units derived from monomers represented by general formula (1) and monomers represented by general formula (2) in the resin forming the resin particles is preferably 2.0% by mass or more and 53.0% by mass or less, based on the total mass of the resin. More preferably, the above percentage (mass%) is 5.0% by mass or more and 50.0% by mass or less. By having the above percentage (mass%) of 5.0% by mass or more and 50.0% by mass or less, an image with even better tensile strength can be obtained. If the above percentage is 5.0% by mass or more, the formation of hydrogen bonds after the aforementioned severance is more likely to occur, and the tensile strength of the image is likely to be further improved. On the other hand, if the above percentage is 50.0% by mass or less, the number of hydrogen bonds is moderately suppressed, and the formation of new hydrogen bonds during severance is more likely to proceed, and the tensile strength of the image is likely to be further improved. The above "total mass of the resin" may include not only the resin particles formed from the monomers constituting the resin, but also solid components such as emulsifiers and polymerization initiators used in the synthesis of the resin.

[0038] The resin forming the resin particles may have units derived from other monomers in addition to units derived from monomers represented by general formula (1) and / or monomers represented by general formula (2). As other monomers, polymerizable monomers copolymerizable with monomers represented by general formula (1) and / or general formula (2) can be used. As polymerizable monomers, compounds having one polymerizable reactive group such as an ethylenically unsaturated bond in the molecule can be used.

[0039] Other monomers include acrylic monomers other than those represented by general formula (1) (hereinafter sometimes referred to as "other acrylic monomers"). Other acrylic monomers include linear or branched alkyl (meth)acrylates, (meth)acrylates having cyclic aliphatic groups, and (meth)acrylates having aromatic groups. Furthermore, other monomers include aromatic group-containing monomers other than acrylic monomers, alkenes, acid group-containing monomers, and acrylamide derivatives other than those represented by general formula (1).

[0040] Examples of linear or branched alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, and hexadecyl (meth)acrylate.

[0041] Examples of (meth)acrylates having a cyclic aliphatic group include monocyclic (meth)acrylates such as cyclopropyl (meth)acrylate, cyclobutyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, cyclooctyl (meth)acrylate, cyclononyl (meth)acrylate, and cyclodecyl (meth)acrylate; bicyclic (meth)acrylates such as isobornyl (meth)acrylate and norbornyl (meth)acrylate; and tricyclic (meth)acrylates such as adamantyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate. Among the (meth)acrylates having a cyclic aliphatic group, cyclohexyl (meth)acrylate and isobornyl (meth)acrylate are preferred because they exhibit good reactivity during polymerization and the resulting resin particles are stable.

[0042] Examples of (meth)acrylates having aromatic groups include benzyl (meth)acrylate, phenylethyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxybutyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, and 2-(2-naphthyloxy)ethyl (meth)acrylate.

[0043] Examples of aromatic group-containing monomers other than acrylic monomers include allylbenzene, styrene, α-methylstyrene, and 4-methylstyrene. Examples of alkenes include ethylene and propylene. Examples of acid group-containing monomers include (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, and carboxyl group-containing monomers such as carboxyethyl (meth)acrylate. Examples of acrylamide monomers other than monomers represented by general formula (1) include acrylamide, methacrylamide, N-methoxymethylacrylamide, N-methoxymethylmethacrylamide, Nn-butoxymethylacrylamide, Nn-butoxymethylmethacrylamide, and Ni-butoxymethylacrylamide.

[0044] Of the other monomers listed above, one or more types may be used. Among the other monomers, linear or branched alkyl (meth)acrylates with 1 to 22 carbon atoms in the alkyl group; cyclohexyl (meth)acrylate; styrene; alkenes with 1 to 22 carbon atoms; (meth)acrylic acid; etc. are preferred. Furthermore, it is more preferable to use linear or branched alkyl (meth)acrylates with 1 to 12 carbon atoms in the alkyl group, as this makes it easier to adjust the thermophysical properties of the resin particles, such as the glass transition temperature, and improves the properties of the formed film. Among these, methyl (meth)acrylate, ethyl (meth)acrylate, and butyl (meth)acrylate are even more preferred.

[0045] The total percentage (by mass) of units derived from other monomers in the resin forming the resin particles is preferably 40.0% by mass or more and 98.0% by mass or less, and more preferably 44.0% by mass or more and 95.0% by mass or less, based on the total mass of the resin.

[0046] Resin particles can be obtained by polymerizing monomers represented by general formula (1) and / or general formula (2), and a monomer mixture containing other monomers as needed. Examples of polymerization methods include radical polymerization, emulsion polymerization, dispersion polymerization, seed polymerization, and suspension polymerization. Emulsifiers and polymerization initiators can be used during polymerization. Furthermore, aqueous dispersions of resin particles (resin particle dispersions) can be prepared according to known methods such as emulsion polymerization, pre-resin particle polymerization, seed polymerization, and phase inversion emulsion. For example, resin particles can be formed and a resin particle dispersion obtained by mixing monomers of the units constituting the resin and performing emulsion polymerization. This emulsion polymerization is preferably carried out in an aqueous liquid medium. Furthermore, a liquid composition can be prepared by mixing the resin particle dispersion and other components used as needed.

[0047] Cumulative 50% particle size (D) of resin particle volume-based particle size distribution 50 ) is preferably 80 nm to 200 nm. D of resin particles 50 If the density is 80 nm or greater, the resin particles are less likely to come too close together, and when the recorded material is stretched, the rearrangement of hydrogen bonds proceeds more smoothly, improving the tensile strength of the image. On the other hand, the density of the resin particles 50 When the diameter is 200 nm or less, the distance between resin particles is prevented from becoming too large, so even if hydrogen bonds are broken when the recorded material is pulled, new hydrogen bonds can easily be formed, which improves the tensile strength of the image. Cumulative 50% particle size (D) of the volume-based particle size distribution of resin particles 50 This can be measured using the particle size distribution analyzer based on the dynamic light scattering method described above.

[0048] The amount of surface acid groups in resin particles is preferably 300 μmol / g or less, more preferably 100 μmol / g or less, and even more preferably 40 μmol / g or less. Surface acid groups in resin particles are acid groups (groups that can have anionic properties when dissociated) present on the surface of the resin particles. "Amount of surface acid groups in resin particles" is expressed as the amount (μmol) of surface acid groups present on the surface of the resin particles per unit mass (g) of resin particles. Therefore, when all the acid groups on the surface of the resin particles have dissociated, the amount of surface acid groups in resin particles can also be expressed as the amount of anionic groups on the surface of the resin particles. By having a surface acid group amount of 40 μmol / g or less, images with even better tensile strength can be obtained. When the surface acid group amount of resin particles is 40 μmol / g or less, the ionic bonding of the acid groups is moderately suppressed, and hydrogen bond rearrangement is more likely to occur when the recording material is pulled, so it is thought that the tensile strength of the image is likely to be further improved. On the other hand, the surface acid group amount (μmol / g) of resin particles is preferably 1 μmol / g or more. The amount of surface acid groups in resin particles can be measured by colloidal titration using a potentiometric titration method, with a sample of a liquid containing resin particles adjusted to pH 12 and a methyl glycol chitosan solution as the titrator. For colloidal titration, an automatic potentiometric titrator equipped with a flow potential titration unit can be used.

[0049] The acid value of the resin forming the resin particles is preferably 18 mg KOH / g or less, and more preferably 15 mg KOH / g or less. An acid value of 15 mg KOH / g or less in the resin forming the resin particles allows for the acquisition of images with even better tensile strength. When the acid value of the resin forming the resin particles is 15 mg KOH / g or less, the ionic bonding of the acid groups is moderately suppressed, making it easier for hydrogen bond rearrangement to occur when the recording material is stretched, thus further improving the tensile strength of the image. The acid value of the resin can be measured using a potentiometric titrator with a potassium hydroxide-ethanol solution as the titration reagent.

[0050] The content (mass%) of resin particles in the liquid composition is preferably 1.0% by mass or more and 12.0% by mass or less, and more preferably 3.0% by mass or more and 10.0% by mass or less, based on the total mass of the liquid composition. By having a resin particle content of 3.0% by mass or more and 10.0% by mass or less, an image with even better tensile strength can be obtained. When the resin particle content is 3.0% by mass or more, the formation of hydrogen bonds after the aforementioned severance is more likely to occur, and the tensile strength of the image is likely to be further improved. On the other hand, when the resin particle content is 10.0% by mass or less, the number of hydrogen bonds is moderately suppressed, and the formation of new hydrogen bonds during the aforementioned severance is more likely to proceed, and the tensile strength of the image is likely to be further improved.

[0051] (Other ingredients) The liquid composition typically contains a liquid medium for dispersing resin particles. The liquid composition may also contain a surfactant. It is preferable to use a liquid medium similar to the aqueous medium used in the ink described later. Therefore, the liquid composition is preferably an aqueous liquid composition containing at least water as the aqueous medium.

[0052] Furthermore, it is preferable that the liquid composition contains at least one compound selected from the group consisting of organic acids, cationic resins, and polyvalent metal salts. By containing at least one compound selected from the group consisting of organic acids, cationic resins, and polyvalent metal salts in the liquid composition, an image with even better tensile strength can be obtained. It is believed that by using the above compounds, the separation of the colorant and resin is promoted within the film in which the image is formed, and the resin's function is made more readily apparent, thus further improving the tensile strength of the image.

[0053] Examples of organic acids include monocarboxylic acids and their salts, such as formic acid, acetic acid, propionic acid, butyric acid, pivalic acid, benzoic acid, glycolic acid, lactic acid, salicylic acid, pyrrolecarboxylic acid, pyrrolidonecarboxylic acid, furanic acid, picolinic acid, nicotinic acid, thiophenecarboxylic acid, levulinic acid, and coumaric acid; dicarboxylic acids and their salts or hydrogen salts, such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, itaconic acid, sebacic acid, phthalic acid, malic acid, and tartaric acid; tricarboxylic acids and their salts or hydrogen salts, such as citric acid and trimellitic acid; and tetracarboxylic acids and their salts or hydrogen salts, such as pyromellitic acid. One or more organic acids can be used. When using organic acids, the content (mass%) of organic acids in the liquid composition is preferably 0.1% by mass or more and 20.0% by mass or less, and more preferably 0.5% by mass or more and 10.0% by mass or less, based on the total mass of the liquid composition.

[0054] Cationic resins are polymers that are positively charged. Examples of cationic resins include resins having the structure of primary to tertiary amines and resins having the structure of quaternary ammonium salts. Specifically, examples include resins having the structures of vinylamine, allylamine, vinylimidazole, vinylpyridine, dimethylaminoethyl methacrylate, ethyleneimine, guanidine, diallyldimethylammonium chloride, and alkylamine-epichlorohydrin condensates. One or more cationic resins can be used. Commercially available cationic resins can also be used. Examples of commercially available products include the trade names "Unisense FPA," "Unisense FCA," "Unisense KCA," and "Unisense KHE" (all manufactured by Senka). Cationic resins are not limited to those listed above; any cationic resin that dissolves or disperses in water can be used. When using a cationic resin, the content (mass%) of the cationic resin in the liquid composition is preferably 0.1% by mass or more and 20.0% by mass or less, and more preferably 0.1% by mass or more and 10.0% by mass or less, based on the total mass of the liquid composition.

[0055] Examples of polyvalent metal ions that make up polyvalent metal salts include Ca 2+ Cu 2+ Ni 2+ Mg 2+ Sr 2+ Ba 2+ , and Zn 2+ Divalent metal ions such as Fe 3+ , Cr 3+ , Y 3+ , and Al 3+ Examples of trivalent metal ions include Cl. - , Br - , I - , - ClO2 - ClO3 - ClO4 - NO2 - NO3 - SO4 2- CO3 2- , HCO3 - , PO4 3- HPO4 2- , and H2PO4 - Inorganic anions such as HCOO - , (COO - )2, COOH(COO - ), CH3COO - C2H5COO - CH3CH(OH)COO - , C2H4(COO - )2, C6H5COO - , C6H4(COO - )2, and CH3SO3 -Organic anions such as the following can be used. One or more polyvalent metal salts can be used. Specific examples of polyvalent metal salts include magnesium sulfate, iron sulfate, and calcium sulfate, but are not limited to these; any polyvalent metal salt that dissolves or disperses in water can be used. When using polyvalent metal salts, the content (mass%) of the polyvalent metal salt in the liquid composition is preferably 0.1% by mass or more and 20.0% by mass or less, and more preferably 0.5% by mass or more and 10.0% by mass or less, based on the total mass of the liquid composition.

[0056] The pH of the liquid composition at 25°C is preferably 7.5 or less, and more preferably 5.0 or less. A pH of 5.0 or less in the liquid composition allows for the acquisition of images with even better tensile resistance. A pH of 5.0 or less in the liquid composition facilitates the rearrangement of hydrogen bonds when the recording material is stretched, thus further improving the tensile resistance of the image. The pH of the liquid composition at 25°C is preferably 2.0 or higher.

[0057] [Water-based ink] The ink in this ink set is a water-based inkjet ink containing colorants. The following provides a detailed explanation of the various components that make up the ink.

[0058] (Colorants) The ink contains a colorant. Pigments and dyes can be used as the colorant, with pigments being preferred. The pigment content (mass%) in the ink is preferably 0.1% by mass or more and 15.0% by mass or less, and more preferably 1.0% by mass or more and 10.0% by mass or less, based on the total mass of the ink.

[0059] Specific examples of pigments include inorganic pigments and organic pigments. Examples of inorganic pigments include carbon black and titanium dioxide. Examples of organic pigments include azo pigments, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, imidazolon pigments, diketopyrrolopyrrole pigments, dioxazine pigments, and perinone pigments. Pigments may be used individually or in combination of two or more.

[0060] As for the dispersion method of the pigment, resin-dispersed pigments using a resin (resin dispersant) as a dispersant, and self-dispersing pigments in which hydrophilic groups are bonded to the surface of the pigment particles can be used. In addition, resin-bonded pigments in which organic groups containing resin are chemically bonded to the surface of the pigment particles, and microcapsule pigments in which the surface of the pigment particles is coated with resin or the like can be used. It is also possible to use a combination of pigments with different dispersion methods from among these. In particular, it is preferable to use resin-dispersed pigments in which the resin as a dispersant is physically adsorbed to the surface of the pigment particles, rather than resin-bonded pigments or microcapsule pigments. That is, it is preferable that the pigment is dispersed by the action of a resin dispersant.

[0061] For the resin dispersant used to disperse the pigment in an aqueous medium, it is preferable to use one that can disperse the pigment in the aqueous medium through the action of anionic groups. As the resin dispersant, a resin having anionic groups can be used, and it is preferable to use a resin such as those described later, and among them, a water-soluble resin. The pigment content (mass%) in the ink is preferably 0.3 times or more and 10.0 times or less by mass ratio to the resin dispersant content.

[0062] Self-dispersing pigments can be those in which anionic groups such as carboxylic acid groups, sulfonic acid groups, and phosphonic acid groups are bonded directly to the particle surface of the pigment or via other atomic groups (-R-). The anionic group may be either acidic or salt-type, and if it is salt-type, it may be in a partially dissociated state or a fully dissociated state. When the anionic group is salt-type, examples of cations that become counterions include alkali metal cations, ammonium, and organic ammonium. Specific examples of other atomic groups (-R-) include linear or branched alkylene groups with 1 to 12 carbon atoms; arylene groups such as phenylene and naphthylene groups; carbonyl groups; imino groups; amide groups; sulfonyl groups; ester groups; and ether groups. Combinations of these groups may also be used.

[0063] (Other resins) The ink may further contain a resin. The resin may be a water-soluble resin, or a water-dispersible resin (resin particle) other than the resin particles used as components of the aforementioned liquid composition. In particular, it is preferable to further contain a water-soluble resin. Examples of water-soluble resins include acrylic resins and urethane resins containing units having carboxylic acid groups and units having aromatic groups.

[0064] (aqueous medium) The ink is an aqueous ink containing at least water as an aqueous medium. The ink may contain an aqueous medium which is water or a mixed solvent of water and a water-soluble organic solvent. Deionized water or ion-exchanged water is preferred as the water. The water content (mass%) in the ink is preferably 40.0% by mass or more and 95.0% by mass or less, and more preferably 50.0% by mass or more and 90.0% by mass or less, based on the total mass of the ink.

[0065] As the water-soluble organic solvent, any of those usable in inkjet inks, such as alcohols, (poly)alkylene glycols, glycol ethers, nitrogen-containing solvents, and sulfur-containing solvents, can be used. The water-soluble organic solvent may be used alone or in combination of two or more. Among the water-soluble organic solvents, alkanediols are preferred. That is, it is preferable that the ink contains an alkanediol as the water-soluble organic solvent. By including an alkanediol in the ink, the flexibility of the recorded image can be further improved. Examples of alkanediols include 1,5-pentanediol, 1,6-hexanediol, 1,2-hexanediol, 1,4-butanediol, 1,3-butanediol, and 1,2-butanediol. The content (mass%) of the water-soluble organic solvent in the ink is preferably 3.0% by mass or more and 50.0% by mass or less, and more preferably 3.0% by mass or more and 45.0% by mass or less, based on the total mass of the ink.

[0066] (Other ingredients) In addition to the above components, the ink may also contain, as needed, organic compounds that are solid at room temperature, such as trimethylolethane and trimethylolpropane, and nitrogen-containing compounds, such as urea and ethylene urea. Furthermore, in addition to the above components, additives such as pH adjusters, rust inhibitors, preservatives, fungicides, antioxidants, reduction inhibitors, evaporation accelerators, and chelating agents may be used as needed.

[0067] (Ink properties) The surface tension of the ink at 25°C is preferably 10 mN / m to 60 mN / m, more preferably 20 mN / m to 60 mN / m, and even more preferably 30 mN / m to 50 mN / m. The viscosity of the ink at 25°C is preferably 1.0 mPa·s to 10.0 mPa·s, more preferably 1.0 mPa·s to 5.0 mPa·s, and even more preferably 1.0 mPa·s to 3.0 mPa·s. The pH of the ink at 25°C is preferably 5.0 to 10.0, and even more preferably 7.0 to 9.5.

[0068] <Ink Cartridge> The ink cartridge of the present invention comprises ink and an ink storage section for storing this ink. The ink stored in this ink storage section is the aqueous ink that constitutes the ink set of the present invention as described above. Figure 1 is a schematic cross-sectional view showing one embodiment of the ink cartridge of the present invention. As shown in Figure 1, an ink supply port 12 for supplying ink to the recording head is provided on the bottom surface of the ink cartridge. The inside of the ink cartridge is an ink storage section for storing ink. The ink storage section consists of an ink storage chamber 14 and an absorbent storage chamber 16, which are in communication with each other via a communication port 18. The absorbent storage chamber 16 is also in communication with the ink supply port 12. Liquid ink 20 is stored in the ink storage chamber 14, and absorbent materials 22 and 24 that hold the ink in an impregnated state are stored in the absorbent storage chamber 16. The ink storage section may not have an ink storage chamber for storing liquid ink, and the entire amount of ink to be stored may be held by an absorbent. Furthermore, the ink reservoir may not have an absorbent and may contain the entire amount of ink in a liquid state. Moreover, the ink cartridge may be configured to include both an ink reservoir and a recording head.

[0069] <Inkjet recording method> The present invention relates to an inkjet recording method that records an image on a recording medium using an aqueous ink containing a colorant and a liquid composition containing specific resin particles. The resin forming the resin particles in the liquid composition is a copolymer having at least one unit selected from the group consisting of a unit derived from a monomer represented by the above-mentioned general formula (1) and a unit derived from a monomer represented by the above-mentioned general formula (2). The aqueous ink and liquid composition used in this inkjet recording method can be the aqueous ink and liquid composition described above, and it is preferable to use the ink set described above.

[0070] The inkjet recording method includes a step of applying a liquid composition to a recording medium (liquid composition application step). Furthermore, this inkjet recording method includes a step of ejecting aqueous ink from an inkjet recording head and applying it to the recording medium so as to overlap at least a portion of the area on the recording medium to which the liquid composition is applied (ink application step). In particular, it is preferable to have a liquid composition application step before the ink application step, or to perform the ink application step and the liquid composition application step in parallel.

[0071] For applying the liquid composition to the recording medium, an inkjet recording head or various coating devices such as coaters and rollers can be used. For applying ink to the recording medium, an inkjet recording head can be used, for example, an inkjet recording device as described later. Methods for ejecting ink from the recording head include methods that impart mechanical energy to the ink and methods that impart thermal energy to the ink. In the present invention, it is particularly preferable to employ a method that imparts thermal energy to the ink to eject it. Aside from using the ink and liquid composition described above, the steps of the inkjet recording method may be those of known origin.

[0072] Figure 2 is a schematic diagram showing an example of an inkjet recording apparatus used in the inkjet recording method of the present invention, where (a) is a perspective view of the main part of the inkjet recording apparatus and (b) is a perspective view of the head cartridge. The inkjet recording apparatus is provided with a transport means (not shown) for transporting the recording medium 32 and a carriage shaft 34. A head cartridge 36 can be mounted on the carriage shaft 34. The head cartridge 36 comprises recording heads 38 and 40 and is configured to hold an ink cartridge 42. While the head cartridge 36 is transported along the carriage shaft 34 in the main scanning direction, ink (not shown) is ejected from the recording heads 38 and 40 toward the recording medium 32. Then, the recording medium 32 is transported in the sub-scanning direction by the transport means (not shown), and an image is recorded on the recording medium 32.

[0073] Any recording medium can be used, and it can be selected according to the intended use of the recorded material containing the image. Examples of recording media include permeable paper such as plain paper and recording media with a coated layer. For example, plain paper, which is suitable for obtaining images of business documents, can be used. In addition, glossy paper, which is suitable for obtaining images with photographic gloss, and art paper, which takes advantage of the texture of the base material (matte, drawing paper, canvas, Japanese paper, etc.) can be used to express paintings, photographs, and graphic images according to preference. In particular, it is preferable to use recording media such as plain paper without a coated layer, or coated paper with a coated layer.

[0074] Furthermore, as low-to-non-absorbent recording media, the following can be used: plastic film; a recording media in which a plastic film is bonded to the recording surface side of a substrate; a recording media in which a resin coating layer is provided on the recording surface of a substrate containing cellulose pulp; and so on. Among these, plastic film is preferred, and a recording media in which a resin coating layer is provided on the recording surface of a substrate containing cellulose pulp is also preferred. "Low-to-non-absorbent recording media" refers to the period from the start of contact to 30 msec in the Bristow method described in JAPAN TAPPI Paper Pulp Test Method No. 51, "Test Method for Liquid Absorption of Paper and Paperboard". 1 / 2 Up to 10 mL / m² of water absorption capacity 2 The recording medium is as follows: [Examples]

[0075] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited in any way by the following examples unless it exceeds the gist of the invention. Unless otherwise specified, amounts of components indicated in "parts" and "%" are based on mass.

[0076] <Synthesis of resin particles> A four-necked flask equipped with a stirrer, nitrogen inlet tube, reflux condenser, and thermometer contained a mixture of monomer species of the types shown in the upper row of Table 1 (Tables 1-1 to 1-5), an emulsifier, and pure water. The amount of each material used in the mixture was such that the proportion of each material in the mixture, including the polymerization initiator used, was as shown in the composition (unit: %) in Table 1. As emulsifiers, the reactive emulsifier Latemul PD-104 (product name of Kao Corporation, ammonium polyoxyalkylene alkenyl ether sulfate) and the non-reactive emulsifier sodium dodecylbenzenesulfonate were used. The mixture in the flask was stirred under a nitrogen atmosphere and heated to 80°C. Then, an initiator solution obtained by dissolving 1 part ammonium persulfate as a polymerization initiator in 20 parts ion-exchanged water was added dropwise over 2 hours, and the polymerization reaction was carried out for 2 hours while stirring at 80°C. After that, an appropriate amount of ion-exchanged water was added to prepare aqueous dispersions of each resin particle with a resin particle (solid content) of 40.0%.

[0077] The lower section of Table 1 shows the characteristics of the aqueous dispersion of each resin particle, specifically the percentage (%) of units derived from the monomer represented by general formula (1) and the monomer represented by general formula (2) in the resin forming the resin particle. It also shows the "acid value (mgKOH / g)" of the resin forming each particle, the "surface acid group content (μmol / g)" of each resin particle, and the "solid content (%)" of the aqueous dispersion of each resin particle.

[0078] TIFF2026141986000007.tif143170

[0079] TIFF2026141986000008.tif143170

[0080] TIFF2026141986000009.tif143170

[0081] TIFF2026141986000010.tif143170

[0082] TIFF2026141986000011.tif145170

[0083] (Acid value of resin) The acid value (mgKOH / g) of the resins forming each resin particle, as shown in the lower section of Table 1, was measured by the following method. For each aqueous dispersion of resin particles, the resin particles were precipitated using a 1.0 mol / L hydrochloric acid aqueous solution, thoroughly washed with water, and then dried at 60°C. The resulting dried material was added to 50 mL of tetrahydrofuran at 50°C and dissolved. After adding 5 mL of water, the mixture was cooled to room temperature to obtain the measurement sample. The acid value of the resin was measured by neutralization titration of the obtained measurement sample. For neutralization titration, a potentiometric automatic titrator (product name "AT510," manufactured by Kyoto Electronics Manufacturing Co., Ltd.) equipped with a composite glass electrode (product name "C-171," manufactured by Kyoto Electronics Manufacturing Co., Ltd.) was used. A 0.5 mol / L potassium hydroxide-ethanol solution was used as the titration reagent.

[0084] (Amount of surface acid groups in resin particles) The amount of surface acid groups (μmol / g) of each resin particle, as shown in the lower section of Table 1, was measured by the following method. For each resin particle aqueous dispersion, the liquid was adjusted to pH 12 and used as a sample. The amount of surface acid groups on the particle surface of the resin particle was measured by colloidal titration using potentiometry. For colloidal titration, a potentiometric automatic titrator (product name "AT510", manufactured by Kyoto Electronics Manufacturing Co., Ltd.) equipped with a flow potentiometry titration unit (product name "PCD-500", manufactured by Kyoto Electronics Manufacturing Co., Ltd.) was used. A 0.005 mol / L methyl glycol chitosan solution was used as the titration reagent.

[0085] (Determination of whether the synthesized resin is resin particles, particle size) For each of the synthesized resin-containing liquids, samples were obtained by diluting them with pure water to adjust the resin content to approximately 1.0%. Then, using a particle size distribution analyzer, the volume-based particle size distribution of the resin particles in the samples was measured, and the cumulative 50% particle size (D) was determined. 50 ) and cumulative 90% particle size (D 90 The particle size distribution was measured. A particle size distribution analyzer using the dynamic light scattering method (product name "NanoTrac WAVE II-Q", manufactured by MicroTrac-Bell) was used as the particle size distribution analyzer. The measurement conditions were as follows. If particles with a particle size were measured using the above method, the sample was determined to be "resin particles" ("water-dispersible resin"), and if particles with a particle size were not measured, the sample was determined not to be "resin particles" ("water-soluble resin"). [Measurement conditions] SetZero: 30 seconds Number of measurements: 10 Measurement time: 120 seconds Shape: true spherical Refractive index: 1.5 Density: 1.0

[0086] <Preparation of Liquid Compositions> Each liquid composition was prepared by mixing the components (in %) shown in the upper row of Table 2 (Tables 2-1 to 2-7), stirring thoroughly, and then pressure filtering through a 2.5 μm pore size microfilter (manufactured by Fujifilm). "Unisense KHE100L" shown in Table 2 is the trade name (manufactured by Senka) for an aqueous solution of cationic resin (60% solids). Also, "Acetylenel E100" shown in Table 2 is the trade name (manufactured by Kawaken Fine Chemicals) for a nonionic surfactant.

[0087] TIFF2026141986000012.tif75170

[0088] TIFF2026141986000013.tif75170

[0089] TIFF2026141986000014.tif75170

[0090] TIFF2026141986000015.tif75170

[0091] TIFF2026141986000016.tif75170

[0092] TIFF2026141986000017.tif75170

[0093] TIFF2026141986000018.tif74170

[0094] <Preparation of Pigment Dispersion> (Pigment dispersion 1) A batch-type vertical sand mill (manufactured by AIMEX) filled with 200.0 parts of 0.3 mm diameter zirconia beads was filled with a mixture of 10.0 parts of carbon black, 20.0 parts of a resin-containing liquid, and 70.0 parts of deionized water, and dispersed for 3 hours. The resin-containing liquid was an aqueous solution with a resin content of 30.0%, obtained by dissolving a water-soluble resin in an aqueous potassium hydroxide solution equimolar to its acid value. This water-soluble resin is a styrene-ethyl acrylate-acrylic acid copolymer with an acid value of 167 mgKOH / g and a weight-average molecular weight of 10,000. After removing coarse particles by centrifugation, the mixture was pressure filtered through a microfilter (manufactured by Fujifilm) with a pore size of 3.0 μm. An appropriate amount of deionized water was added to adjust the concentration to obtain pigment dispersion 1 with a pigment (carbon black) content of 10.0%.

[0095] (Pigment dispersion 2) Pigment dispersion 2, with a pigment (phthalocyanine pigment) content of 10.0%, was obtained in the same manner as pigment dispersion 1, except that phthalocyanine pigment was used instead of carbon black.

[0096] <Ink preparation> Each ink was prepared by mixing the components shown in Table 3 (in %), stirring thoroughly, and then pressure filtering through a 2.5 μm pore size microfilter (manufactured by Fujifilm). "Acetylenel E100" shown in Table 3 is the trade name of a nonionic surfactant (manufactured by Kawaken Fine Chemicals).

[0097] TIFF2026141986000019.tif42170

[0098] <Rating> The types of inks and liquid compositions shown in Table 4 were used as ink sets. Each type of ink shown in Table 4 was filled into an ink cartridge. The ink cartridges filled with ink were set in an inkjet recording device (product name "PIXUS Pro9500", manufactured by Canon) equipped with a recording head that ejects ink by the action of thermal energy. In this embodiment, a solid image recorded by applying 8 ink droplets, each with a mass of 3.5 nanograms, to a unit area of ​​1 / 600 inch x 1 / 600 inch is defined as having a "recording duty cycle of 100%".

[0099] A liquid composition of the types shown in Table 4 was applied to an A4-sized polyethylene terephthalate (PET) film, which served as the recording medium, using an application roller. Next, ink was applied using the above-mentioned inkjet recording device with a recording duty cycle of 100%, so as to overlap with the liquid composition applied to the recording medium, and a solid 5cm x 5cm image was recorded. After that, the recording was dried by placing it in an 80°C oven for 3 minutes to obtain the recorded material.

[0100] (Tensile strength) The tensile strength evaluation was performed by placing the recorded material with the image-bearing side (printed side) facing upwards, folding it until a crease was formed so that the printed side was facing outwards, and visually inspecting the condition of the area where the image was recorded. The evaluation was then judged according to the following criteria. AA, A, and B were judged to be at a level suitable for actual use, while C was judged to be not at a level suitable for actual use. AA: No image tears were observed. A: A tear was visible in part of the image along the fold, but the white paper underneath was not exposed. B: Tears were visible throughout the image along the folds, but the white paper underneath was not exposed. C: The image showed tears along the folds, and the white paper underneath was also exposed.

[0101] TIFF2026141986000020.tif211170

[0102] Furthermore, the disclosure of this embodiment includes the following configurations and methods. (Configuration 1) An inkjet ink set comprising an aqueous ink containing a colorant and a liquid composition containing resin particles, An ink set characterized in that the resin forming the resin particles is a copolymer having at least one unit selected from the group consisting of a unit derived from a monomer represented by the following general formula (1) and a unit derived from a monomer represented by the following general formula (2).

[0103] TIFF2026141986000021.tif33170(In the above general formula (1), R 1 R represents a hydrogen atom or a methyl group. 2 (where 'NH represents an oxygen atom, 'X' represents a methylene group, and 'm' represents an integer from 1 to 6.)

[0104] TIFF2026141986000022.tif12170 (In the above general formula (2), Y represents an oxyalkylene group having 2 to 4 carbon atoms, and n represents an integer from 1 to 3.)

[0105] (Configuration 2) The ink set according to Configuration 1, wherein the pH of the liquid composition at 25°C is 5.0 or less. (Configuration 3) The ink set according to Configuration 1 or 2, wherein the surface acid group content of the resin particles is 40 μmol / g or less. (Configuration 4) The ink set according to any one of Configurations 1 to 3, wherein the acid value of the resin forming the resin particles is 15 mg KOH / g or less. (Configuration 5) The ink set according to any one of Configurations 1 to 4, wherein the total proportion (mass%) of the units derived from the monomer represented by general formula (1) and the units derived from the monomer represented by general formula (2) in the resin forming the resin particles is 5.0% by mass or more and 50.0% by mass or less, based on the total mass of the resin. (Configuration 6) The ink set according to any one of Configurations 1 to 5, wherein the content (mass%) of the resin particles in the liquid composition is 3.0% by mass or more and 10.0% by mass or less, based on the total mass of the liquid composition. (Configuration 7) The ink set according to any one of Configurations 1 to 6, wherein the resin forming the resin particles is a copolymer having units derived from the monomer represented by the general formula (1), and the monomer represented by the general formula (1) comprises 2-hydroxyethyl methacrylate. (Configuration 8) The ink set according to any one of Configurations 1 to 7, wherein the liquid composition contains at least one compound selected from the group consisting of organic acids, cationic resins, and polyvalent metal salts. (Method 1) An inkjet recording method for recording an image on a recording medium using an aqueous ink containing a colorant and a liquid composition containing resin particles, A step of applying the liquid composition to the recording medium, The process includes dispensing aqueous ink from an inkjet recording head and applying it to the recording medium such that it overlaps with at least a portion of the area on the recording medium to which the liquid composition is applied, An inkjet recording method characterized in that the resin forming the resin particles is a copolymer having at least one unit selected from the group consisting of a unit derived from a monomer represented by the following general formula (1) and a unit derived from a monomer represented by the following general formula (2).

[0106] TIFF2026141986000023.tif33170(In the above general formula (1), R 1 R represents a hydrogen atom or a methyl group. 2 (where 'NH represents an oxygen atom, 'X' represents a methylene group, and 'm' represents an integer from 1 to 6.)

[0107] TIFF2026141986000024.tif12170 (In the above general formula (2), Y represents an oxyalkylene group having 2 to 4 carbon atoms, and n represents an integer from 1 to 3.)

Claims

1. An inkjet ink set comprising an aqueous ink containing a colorant and a liquid composition containing resin particles, An ink set characterized in that the resin forming the resin particles is a copolymer having at least one unit selected from the group consisting of a unit derived from a monomer represented by the following general formula (1) and a unit derived from a monomer represented by the following general formula (2). (In the above general formula (1), R １ R represents a hydrogen atom or a methyl group. ２ (where 'n' represents NH or an oxygen atom, 'X' represents a methylene group, and 'm' represents an integer from 1 to 6.) (In the general formula (2) above, Y represents an oxyalkylene group having 2 to 4 carbon atoms, and n represents an integer from 1 to 3.)

2. The ink set according to claim 1, wherein the pH of the liquid composition at 25°C is 5.0 or less.

3. The ink set according to claim 1, wherein the surface acid group content of the resin particles is 40 μmol / g or less.

4. The ink set according to claim 1, wherein the acid value of the resin forming the resin particles is 15 mg KOH / g or less.

5. The ink set according to claim 1, wherein the total proportion (mass%) of the units derived from the monomer represented by general formula (1) and the units derived from the monomer represented by general formula (2) in the resin forming the resin particles is 5.0% by mass or more and 50.0% by mass or less, based on the total mass of the resin.

6. The ink set according to claim 1, wherein the content (mass%) of the resin particles in the liquid composition is 3.0% by mass or more and 10.0% by mass or less, based on the total mass of the liquid composition.

7. The ink set according to claim 1, wherein the resin forming the resin particles is a copolymer having units derived from a monomer represented by the general formula (1), and the monomer represented by the general formula (1) comprises 2-hydroxyethyl methacrylate.

8. The ink set according to claim 1, wherein the liquid composition contains at least one compound selected from the group consisting of organic acids, cationic resins, and polyvalent metal salts.

9. An inkjet recording method for recording an image on a recording medium using an aqueous ink containing a colorant and a liquid composition containing resin particles, A step of applying the liquid composition to the recording medium, The process includes dispensing aqueous ink from an inkjet recording head and applying it to the recording medium such that it overlaps with at least a portion of the area on the recording medium to which the liquid composition is applied, An inkjet recording method characterized in that the resin forming the resin particles is a copolymer having at least one unit selected from the group consisting of a unit derived from a monomer represented by the following general formula (1) and a unit derived from a monomer represented by the following general formula (2). (In the above general formula (1), R １ R represents a hydrogen atom or a methyl group. ２ (where 'n' represents NH or an oxygen atom, 'X' represents a methylene group, and 'm' represents an integer from 1 to 6.) (In the general formula (2) above, Y represents an oxyalkylene group having 2 to 4 carbon atoms, and n represents an integer from 1 to 3.)

Images