Inkjet ink composition and recording method

Abstract

To provide an inkjet ink composition having good water resistance and dispersion stability of a metallic pigment and capable of obtaining a recorded matter having excellent metallic gloss.SOLUTION: There is provided an inkjet ink composition which comprises a metallic pigment, a polyoxyalkylene amine compound and an organic solvent, wherein the metallic pigment is metal particles, the surface of which is treated with a surface treating agent, the surface treating agent is a compound represented by the following formula (1) or the following formula (2), the polyoxyalkylene amine compound includes a compound represented by the following formula (3) and the compound represented by the formula (3) has an average of m / (m+n)×100(%) of 20% or more and is a solvent-based ink. (R1-)P(O)(OH)2 (1), (R2-O-)aP(O)(OH)3-a (2) (wherein, R1 and R2 each independently represent a hydrocarbon group having 14 or more carbon atoms which may be substituted with a substituent and a represents 1 or 2.) R3(OC2H4)m-(OC3H6)n-NH2 (3) (wherein, R3 represents a hydrogen atom or an alkyl group having 4 or less carbon atoms, m represents an integer of 1 or more, n represents an integer of 0 or more and m+n represents an integer of 10 or more. Provided that the arrangement order of an oxyethylene unit (OC2H4) and an oxypropylene unit (OC3H6) is optional.)SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an inkjet ink composition and a recording method.

Background Art

[0002] Conventionally, compositions such as inks and paints containing metal pigments such as aluminum have been developed for manufacturing articles having a metallic luster. For example, Patent Document 1 discloses a metal ink using an aluminum pigment. The aluminum pigment disclosed in Patent Document 1 is surface-treated with a fluorine-based treatment agent.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in an inkjet ink composition containing a metal pigment, the dispersion stability of the metal pigment and the brilliance of the obtained image are still problems. In addition, when treating the surface of the metal pigment, oxidation of the metal pigment may progress during the treatment, resulting in problems such as a decrease in gloss and an easy occurrence of aggregation of the metal pigment.

[0005] Therefore, there is a demand for an inkjet ink composition that has good dispersion stability of the metal pigment and can obtain a recording material with excellent metallic luster.

Means for Solving the Problems

[0006] One aspect of the inkjet ink composition according to the present invention is a solvent-based inkjet ink composition, It contains a metal pigment, a polyoxyalkyleneamine compound, and an organic solvent. The metal pigment is metal particles whose surface is treated with a surface treatment agent. The surface treatment agent is a compound represented by the following formula (1) or the following formula (2). The polyoxyalkyleneamine compound includes a compound represented by the following formula (3). In the compound represented by the formula (3), the average of m / (m + n)×100(%) is 20% or more. (R 1 -)P(O)(OH)2···(1) (R 2 -O-) a P(O)(OH) 3-a ···(2) (In formula (1) and formula (2), R 1 , R 2 each independently represents a hydrocarbon group having 14 or more carbon atoms which may be substituted with a substituent, and a represents 1 or 2.) R 3 (OC2H4) m -(OC3H6) n -NH2···(3) (In formula (3), R 3 represents a hydrogen atom or an alkyl group having 4 or fewer carbon atoms, m represents an integer of 1 or more, n represents an integer of 0 or more, and m + n represents an integer of 10 or more. However, the order of the oxyethylene unit (OC2H4) and the oxypyropylene unit (OC3H6) is arbitrary.)

[0007] One aspect of the recording method according to the present invention includes a step of attaching the above-described inkjet ink composition to a recording medium.

Brief Description of the Drawings

[0008] [Figure 1] A schematic cross-sectional view schematically showing a recording device.

Embodiments for Carrying Out the Invention

[0009] Embodiments of the present invention are described below. The embodiments described below illustrate examples of the present invention. The present invention is not limited in any way to the embodiments described below and includes various modifications that are implemented without changing the gist of the present invention. Not all of the configurations described below are necessarily essential to the present invention.

[0010] In this specification, "(meth)acrylic" means acrylic or methacrylic, and "(meth)acrylate" means acrylate or methacrylate. Also, "inkjet ink composition" may be referred to as "composition," and inkjet ink composition may be referred to as "ink composition" or "ink."

[0011] 1. Inkjet ink composition The inkjet ink composition according to this embodiment is an organic solvent-based inkjet ink composition containing a metal pigment, a polyoxyalkyleneamine compound, and an organic solvent. 1.1. Metallic Pigments Metallic pigments are metal particles whose surfaces have been treated with a surface treatment agent. More specifically, metallic pigments include embodiments in which the surface treatment agent is attached to the surface of the metal particles by chemical bonding or physical adsorption.

[0012] 1.1.1. Metal particles The metal particles are composed of a metallic material in at least a portion of their visible surface, for example, the entire particle or the area near its outer surface is composed of a metallic material. The metal particles have the function of imparting metallic luster to records produced using an inkjet ink composition.

[0013] The metal particles only need to be composed of a metallic material in a region including the vicinity of the surface. For example, they may be entirely composed of a metallic material, or they may have a base made of a non-metallic material and a coating made of a metallic material covering the base. Furthermore, the metal particles may have a passive film such as an oxide film formed on their surface. Even with such metal particles, problems such as water resistance and metallic luster have conventionally occurred, but the inkjet ink composition of this embodiment can obtain excellent water resistance and metallic luster.

[0014] As the metal material constituting the metal particles, elemental metals and various alloys can be used. Examples include aluminum, silver, gold, platinum, nickel, chromium, tin, zinc, indium, titanium, iron, copper, and alloys containing at least one of these metals. Of these, the metal particles are preferably made of aluminum or an aluminum alloy, and more preferably of aluminum. One reason why aluminum and aluminum alloys are preferred is that they have a lower specific gravity compared to metals such as iron. As a result, the sedimentation of the metal pigment dispersed in the ink proceeds very slowly, which tends to suppress the occurrence of uneven concentration and allows the composition to be stored for a longer period of time. Furthermore, using metal pigments made of aluminum or aluminum alloy metal particles can further improve the gloss and luxurious feel of the recorded material while suppressing an increase in the production cost of the recorded material manufactured using the inkjet ink composition.

[0015] Aluminum and aluminum alloys inherently exhibit superior luster among various metallic materials, but when particles composed of these materials are applied to a composition, the following problems may arise. Specifically, the storage stability (water resistance) of the composition tends to be low, and when the composition is used as an inkjet ink composition, gelation occurs. Problems such as decreased discharge stability due to increased viscosity are likely to occur. However, even if the metal pigment uses metal particles made of aluminum or an aluminum alloy, surface treatment with a specific surface treatment agent described later in this embodiment can make such problems less likely to occur. In other words, the effect of the composition of this embodiment becomes more pronounced when the metal particles are aluminum or an aluminum alloy.

[0016] The metal particles may be spherical, spindle-shaped, needle-shaped, or any other shape, but they are preferably flaky. This makes it easier for the main surface of the metal particles to be arranged to conform to the surface shape of the object to which the composition is applied. As a result, the luster and other properties of the metal material constituting the metal particles can be more effectively exhibited in the resulting recording, resulting in a superior gloss and high-quality feel of the recording. Furthermore, when the metal particles are flaky, the recording tends to have better scratch resistance.

[0017] In this specification, "scale-like" refers to a shape such as a flat plate or a curved plate, in which, when observed from a predetermined angle, for example, the area when viewed from above is larger than the area when observed from an angle perpendicular to the direction of observation. In particular, the area S1 [μm²] when observed from the direction that maximizes the projected area, i.e., when viewed from a planar perspective. 2 ] and the area S0 [μm²] observed from the direction perpendicular to the observation direction that yields the largest observed area. 2 The ratio S1 / S0 to ] is preferably 2 or more, more preferably 5 or more, and even more preferably 8 or more. Furthermore, 10 or more is preferred, and 20 or more is even more preferred. Even more preferably 30 or more. The upper limit of S1 / S0 is not particularly limited, but it is preferably 1000 or less, more preferably 500 or less, and even more preferably 100 or less. Even more preferably 80 or less.

[0018] For this value, for example, observations can be performed on any 50 particles, and the average value calculated for these particles can be adopted. Observations can be performed using, for example, an electron microscope or an atomic force microscope. Alternatively, the volume-average particle diameter (D50) and average thickness described later can be used, and after matching the units, the value can be calculated as volume-average particle diameter (D50) / average thickness, and this can be used as the above range.

[0019] When the metal particles are in the form of flakes, the average thickness of the metal particles is preferably 5 nm or more and 90 nm or less. The lower limit of the average thickness of the metal particles is not particularly limited, but it is more preferably 10 nm or more, and even more preferably 15 nm or more. Also, when the metal particles are in the form of flakes, the upper limit of the average thickness of the metal particles is not particularly limited, but it is more preferably 70 nm or less, even more preferably 50 nm or less, particularly preferably 30 nm or less, even more preferably 20 nm or less, and even more preferably 15 nm or less.

[0020] When the metal particles are flaky and have an average thickness of 5 nm to 90 nm, preferably within the above range, the effects of the flaky particle shape described above become more pronounced.

[0021] The average thickness of metal particles can be measured using an atomic force microscope (AFM), similar to the average thickness of metal pigments described later. For example, measurements can be taken on any 50 metal particles using atomic force microscopy, and the average value can be taken. In other words, the average thickness is the arithmetic mean thickness.

[0022] The preferred range and measurement method for the volume-average particle diameter (D50) of metal particles can be the same as that for the volume-average particle diameter (D50) of metal pigments, as described later. In other words, it is measured as the volume-average particle diameter D50 using a laser diffraction / scattering particle size distribution analyzer.

[0023] The metal particles may be manufactured by any method, but if they are made of aluminum, it is preferable that they are obtained by forming an aluminum film using a vapor deposition method and then crushing the film. This method also helps to suppress variations in properties between individual particles. Furthermore, by using this method, even relatively thin metal particles can be suitably manufactured.

[0024] When producing metal particles using such a method, for example, metal particles can be suitably produced by forming a film made of aluminum on a substrate. As the substrate, for example, a plastic film such as polyethylene terephthalate can be used. The substrate may also have a release agent layer on the film-forming surface.

[0025] Furthermore, grinding is preferably carried out by applying ultrasonic vibrations to the film in a liquid. This makes it possible to easily obtain metal particles of the aforementioned particle size, and also suppresses the occurrence of variations in size, shape, and properties among the individual metal particles.

[0026] Furthermore, when grinding is performed using the method described above, suitable liquids include alcohols, hydrocarbon compounds, ether compounds, and polar compounds such as propylene carbonate, γ-butyrolactone, N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, cyclohexanone, and acetonitrile. By using such liquids, it is possible to suppress unintended oxidation of metal particles, achieve particularly excellent productivity of metal particles, and minimize variations in size, shape, and properties between individual particles.

[0027] 1.1.2. Surface treatment agents Metallic pigments are metal particles whose surfaces have been treated with a compound represented by formula (1) or formula (2) as a surface treatment agent. The surface treatment agent used to treat the surface of the metal particles is a compound represented by the following general formula (1) or general formula (2). (R 1 -)P(O)(OH)2···(1) (R 2 -O-) a P(O)(OH) 3-a ...(2) (In the formula, R 1 , R 2 (where a independently represents a hydrocarbon group having 14 or more carbon atoms, which may be substituted with substituents, and a represents 1 or 2.)

[0028] The compound represented by the above general formula (1) (substituted or unsubstituted alkyl phosphonic acid) is a compound in which the hydrogen atoms of the phosphonic acid are (R 1 These compounds are substituted with a - group. Because such compounds exhibit little steric hindrance due to the alkyl moiety, they are easily uniformly distributed on the surface of metal particles, improving the dispersion stability and gloss of the metal pigment.

[0029] The compound represented by the above general formula (2) is a compound in which one or two of the three hydroxyl groups of phosphoric acid are esterified with a substituted or unsubstituted alkyl group.

[0030] The compound represented by general formula (2) is a diester of a substituted or unsubstituted alkyl group when a is 1, and a monoester of a substituted or unsubstituted alkyl group when a is 2. When a is 1 (diester), the compound represented by general formula (2) has two substituted or unsubstituted alkyl moieties, which sterically hindrances the metal particle surface, making it more difficult for water to approach, and thus tends to make the metal pigment more water-resistant. Hereafter, "monoester" may be referred to as "monoester," and "diester" may be referred to as "diester."

[0031] In the above formula, R 1 and R 2 This refers to a monovalent hydrocarbon group having a carbon skeleton with 14 or more carbon atoms. The hydrocarbon group may contain saturated or unsaturated bonds.

[0032] R1 , R 2 It may be independently substituted with one or more substituents, for example, a carboxyl group, a hydroxyl group, an amino group, or an oxyalkylene-containing group. If it has substituents, the R to which the substituent is attached 1 or R 2 The position of the group is more preferable when it is bonded to the carbon atom furthest from P or O, as this tends to result in better dispersion stability of the metal pigment. Of these, the oxyalkylene-containing group is a group having an oxyalkylene structure, which is also called an alkylene oxide structure.

[0033] The oxyalkylene-containing group has one or more alkylene oxide units, and may have two or more. In particular, it may have a structure in which multiple alkylene oxide units are repeated. The number of repeating alkylene oxide units is preferably 10 or less, more preferably 4 or less. The lower limit is 1 or more, preferably 2 or more, and more preferably 3 or more. The number of alkylene carbon atoms in the alkylene oxide unit is preferably 1 or more and 4 or less.

[0034] Examples of hydrocarbon groups having a carbon skeleton with 14 or more carbon atoms include saturated hydrocarbon groups that do not have double or tripolymer bonds between carbon atoms, and unsaturated hydrocarbon groups that have double or tripolymer bonds between carbon atoms. The hydrocarbon group may also be an aromatic hydrocarbon group having an aromatic ring structure in its carbon skeleton, or a linear or cyclic aliphatic hydrocarbon group. Linear aliphatic hydrocarbon groups are particularly preferred because they offer superior dispersion stability and other advantages. Aliphatic hydrocarbon groups having a linear skeleton may be branched or linear, but linear types are preferred because they offer superior dispersion stability, discharge stability, and gloss.

[0035] The compound represented by the above general formula (1) and the compound represented by the above general formula (2) are R in the formula. 1 , R 2However, each is preferably a hydrocarbon group having 14 to 32 carbon atoms, more preferably a hydrocarbon group having 15 to 30 carbon atoms, even more preferably a hydrocarbon group having 16 to 22 carbon atoms, and especially preferably a hydrocarbon group having 16 to 20 carbon atoms. By doing so, the dispersion stability and water resistance of the inkjet ink composition are improved, and even if sedimentation of the components occurs, the components can be redispersed more easily. 1 and R 2 This may be an unsubstituted hydrocarbon group.

[0036] Note that R in the above general formulas (1) and (2) 1 , R 2 Preferably, the carbon atoms have the same number of carbon atoms, and more preferably, they are hydrocarbon groups with the same structure. This increases the tendency for the surface treatment agent to adhere uniformly to the surface of the metal particles, resulting in a better balance of water resistance and glossiness of the recorded material.

[0037] Specific examples of compounds represented by the above general formula (1) include tetradecylphosphonic acid (myristylphosphonic acid), hexadecylphosphonic acid (cetylphosphonic acid), octadecylphosphonic acid (stearylphosphonic acid), and it is preferable that one or more are selected from these. More preferably, one or more are selected from hexadecylphosphonic acid (cetylphosphonic acid) and octadecylphosphonic acid (stearylphosphonic acid), and it is even more preferable that it is octadecylphosphonic acid (stearylphosphonic acid).

[0038] Specific examples of the mono-form of the compound represented by the general formula (2) above include monostearyl phosphate esters.

[0039] A specific example of the di-isomer of the compound represented by the above general formula (2) is distearyl phosphate.

[0040] Among the compounds represented by formula (2), the compound in which a is 2, i.e., the phosphate diester (di-form), has two alkyl groups, and since more alkyl groups can be introduced onto the metal particle surface, the hydrophobicity of the pigment surface is increased, and the water resistance of the pigment can be improved.

[0041] The surface treatment agent more preferably contains either the compound represented by formula (1) or the compound represented by formula (2) in which a is represented by 2. In this way, the surface treatment agent tends to adhere more uniformly to the surface of the metal particles, and a better balance of water resistance and gloss can be achieved.

[0042] Furthermore, the surface treatment agent is present in an amount of 0.5% to 60% by mass, preferably 1% to 50% by mass, more preferably 5% to 40% by mass, even more preferably 5% to 30% by mass, particularly preferably 5% to 20% by mass, and even more preferably 5% to 15% by mass, based on 100% by mass of the total mass of the metal particles. With such a ratio, water resistance is further improved, and even if sedimentation of the components occurs, the components can be redispersed even more easily.

[0043] The mass of the surface treatment agent is the mass of the surface treatment agent contained in the inkjet ink composition. If the surface treatment agent contained in the inkjet ink composition is a surface treatment agent attached to metal particles, then the mass of the surface treatment agent is also the mass of the surface treatment agent attached to the metal particles.

[0044] The inkjet ink composition according to this embodiment may contain surface treatment agents other than those described above, as long as the effects of the present invention are not impaired. Examples of such surface treatment agents include fluorine-based compounds. Preferably, fluorine-based compounds include compounds containing fluorine and one or more elements selected from phosphorus, sulfur, and nitrogen as constituent elements. Specifically, examples include fluorine-based phosphonic acids, fluorine-based carboxylic acids, fluorine-based sulfonic acids, and salts thereof.

[0045] Surface treatment of metal particles with a surface treatment agent may be carried out, for example, by including the surface treatment agent in the liquid when forming metal particles by crushing a metal film formed by a vapor phase deposition method in a liquid.

[0046] 1.1.3. Volume-average particle diameter The volume-average particle diameter D50 of a metal pigment obtained by treating metal particles with a surface treatment agent is preferably 1 μm or less, more preferably 0.5 μm or less, and even more preferably 20 nm to 500 nm. Furthermore, 50 nm to 400 nm is preferred, 100 nm to 350 nm is more preferred, and 200 nm to 300 nm is even more preferred.

[0047] If the particle size of the metal pigment is within the above range, nozzle clogging during inkjet ejection can be further reduced. Furthermore, if the particle size of the metal pigment is within the above range, good water resistance and sufficient dispersibility can be more easily obtained even if the specific surface area of ​​the metal pigment is large.

[0048] The volume-average particle size D50 of metallic pigments can be measured in the same manner as described in the section on metallic particles.

[0049] The content of metal pigments in the inkjet ink composition is preferably 0.3% to 30% by mass, more preferably 0.5% to 20% by mass, even more preferably 0.8% to 15% by mass, and even more preferably 1.0% to 10% by mass, relative to the total amount of the inkjet ink composition. 1.0% to 5.0% by mass is particularly preferred.

[0050] 1.2. Polyoxyalkyleneamine compounds The inkjet ink composition contains a polyoxyalkyleneamine compound. The polyoxyalkyleneamine compound may be any amine compound having a polyoxyalkylene structure in its molecule, but it is preferably at least one of the compounds represented by the following formula (3) and its salts.

[0051] R 3 (OC2H4) m -(OC3H6) n -NH2···(3) (In formula (3), R 3 ∫ represents a hydrogen atom or an alkyl group having 4 or fewer carbon atoms, m represents an integer of 1 or more, n represents an integer of 0 or more, and m+n represents an integer of 10 or more. However, the order of the oxyethylene unit (OC2H4) and the oxypyroprene unit (OC3H6) is arbitrary.

[0052] Furthermore, the compound represented by formula (3) has an average m / (m+n) × 100 (%) of 20% or more. Preferably, the average m / (m+n) × 100 (%) is 30% or more, more preferably 50% or more, and even more preferably 60% or more. The upper limit is 100% or less. Even more preferably, it is 70% to 95%, more preferably 73% to 90%, even more preferably 75% to 85%, and particularly preferably 75% to 80%.

[0053] By selecting a compound represented by formula (3) within this range, the storage stability of the inkjet ink composition can be further improved, resulting in improved ejection stability of the inkjet ink composition and glossiness of the produced records when the inkjet ink composition is stored for a long period of time or under harsh conditions.

[0054] Furthermore, for the compound represented by formula (3) above, the lower limit of the m / n value, which is the ratio of m to n, that is, the ratio of the amount of oxyethylene units to the amount of oxypropylene units within the molecule of the polyoxyalkyleneamine compound, is preferably 0.05, more preferably 0.15, and even more preferably 0.70. The upper limit of the m / n value is preferably 10.00, more preferably 8.00, and even more preferably 6.00.

[0055] This further improves the storage stability of the inkjet ink composition, resulting in improved ejection stability and glossiness of the produced records when the inkjet ink composition is stored for long periods or under harsh conditions.

[0056] As described above, the order of the oxyethylene unit and the oxypropylene unit in formula (3) does not matter. More specifically, in formula (3), an amino group is bonded to the end of a series of oxyethylene units and a methyl group is bonded to the end of a series of oxypropylene units, but it is also possible for an amino group to be bonded to the end of a series of oxypropylene units and a methyl group to be bonded to the end of a series of oxyethylene units. Furthermore, the compound represented by formula (3) may be a block copolymer or a random copolymer.

[0057] The lower limit of the weight-average molecular weight of the polyoxyalkyleneamine compound is not particularly limited, but is preferably 300, more preferably 500, even more preferably 800, and most preferably 1000. The upper limit of the weight-average molecular weight of the polyoxyalkyleneamine compound is not particularly limited, but is preferably 8000, more preferably 5000, and even more preferably 3000.

[0058] This further improves the storage stability of the inkjet ink composition, resulting in improved ejection stability and glossiness of the produced records when the inkjet ink composition is stored for long periods or under harsh conditions.

[0059] The oxyethylene unit has higher hydrophilicity compared to the oxypropylene unit. Metal particles whose surfaces are treated with the compound represented by formula (1) or formula (2) as a surface treatment agent exhibit excellent dispersion stability with respect to the organic solvents of solvent-based inks. It is presumed that the compound represented by formula (1) or formula (2) has excellent affinity for organic solvents and imparts this affinity to the metal particles.

[0060] However, metal particles whose surfaces are treated with the compound represented by formula (1) or formula (2) are presumed to be slightly less hydrophobic and more hydrophilic compared to metal particles whose surfaces are treated with conventionally used fluorine-based treatment agents. For metal particles whose surfaces are treated with the compound represented by formula (1) or formula (2), it is presumed that the dispersion stability of the metal pigment is excellent when the polyoxyalkyleneamine compound shown in formula (3) has an average m / (m+n) × 100 (%) of 20% or more and a predetermined ratio of oxyethylene units.

[0061] Furthermore, the compound represented by formula (3) is preferably present in an amount of 20% to 80% by mass, more preferably 30% to 60% by mass, and even more preferably 30% to 50% by mass, based on 100% by mass of the total mass of the metal particles. This further improves the dispersibility of the metal pigment.

[0062] The lower limit of the content of polyoxyalkyleneamine compounds in the inkjet ink composition is not particularly limited, but is preferably 0.01% by mass, more preferably 0.06% by mass, and even more preferably 0.10% by mass. It is even more preferably 0.40% by mass or more, and even more preferably 0.50% by mass or more. Furthermore, while there is no particular upper limit to the content of polyoxyalkyleneamine compounds in the inkjet ink composition, it is preferably 3.0% by mass, more preferably 2.0% by mass, and even more preferably 1.5% by mass. Moreover, it is even more preferably 0.70% by mass.

[0063] This makes it possible to achieve particularly excellent ejection stability of inkjet ink compositions produced by the inkjet method, and also to achieve particularly excellent glossiness of printed areas formed using the inkjet ink composition.

[0064] 1.3. Organic Solvents Inkjet ink compositions contain organic solvents and are solvent-based inks. The organic solvents primarily function as dispersion media for dispersing metal particles.

[0065] Furthermore, the inclusion of an organic solvent in the inkjet ink composition enables the inkjet ink composition to be ejected by inkjet. The inkjet ink composition is preferably an inkjet ink composition. A solvent-based ink is a composition that contains an organic solvent as a solvent component and does not use water as a solvent component. The content of the organic solvent in the inkjet ink composition is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more, based on the total amount of the inkjet ink composition. It is even more preferably 70% by mass or more and 99% by mass or less, and even more preferably 80% by mass or more and 98% by mass or less. On the other hand, the water content in the inkjet ink composition is 1% by mass or less, preferably 0.5% by mass or less, and more preferably 0.1% by mass or less.

[0066] The organic solvent is preferably composed of a liquid component other than water, usually an organic solvent. Examples of organic solvents include glycol ether-based organic solvents and lactone-based organic solvents. Furthermore, ester compounds, ether compounds, hydroxyketones, diester carbonates, cyclic amide compounds, etc., can be used. More specifically, compounds that can be used as organic solvents include, for example, 2-(2-methoxy-1-methylethoxy)-1-methylethyl acetate, triethylene glycol dimethyl ether, triethylene glycol diacetate, diethylene glycol monoethyl ether acetate, 4-methyl-1,3-dioxolan-2-one, bis(2-butoxyethyl) ether, dimethyl glutarate, ethylene glycol di-n-butyrate, 1,3-butylene glycol diacetate, diethylene glycol monobutyl ether acetate, tetraethylene glycol dimethyl ether, 1,6-diacetoxyhexane, tripropylene glycol monomethyl ether, butoxypropanol, diethylene glycol methyl ethyl ether, diethylene glycol methyl butyl ether, triethylene glycol methyl ethyl ether, triethylene glycol methyl butyl ether, and dipropylene glycol monomethyl ether acetate. Diethylene glycol dimethyl ether, 3-ethoxypropionate ethyl ethyl methyl ether, 3-methoxybutyl acetate, diethylene glycol diethyl ether, octanoate ethyl ethyl ethyl ethyl ethylene glycol monobutyl ether acetate, ethylene glycol monobutyl ether, cyclohexyl acetate, diethyl succinate, ethylene glycol diacetate, propylene glycol diacetate, 4-hydroxy-4-methyl-2-pentanone, dimethyl succinate, 1-butoxy-2-propanol, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, 3-methoxy-n-butyl acetate, diacetin, dipropylene glycol mono-n-propyl ether, polyethylene glycol monomethyl ether, butyl glycolate, ethylene glycol monohexyl ether, dipropylene glycol mono-n-butyl ether,N-methyl-2-pyrrolidone, triethylene glycol butyl methyl ether, bis(2-propoxyethyl) ether, diethylene glycol diacetate, diethylene glycol butyl methyl ether, diethylene glycol butyl ethyl ether, diethylene glycol butyl propyl ether, diethylene glycol ethyl propyl ether, diethylene glycol methyl propyl ether, diethylene glycol propyl ether acetate, triethylene glycol methyl ether acetate, triethylene glycol ethyl ether acetate, triethylene glycol propyl ether acetate, triethylene glycol butyl ether acetate, triethylene glycol butyl ethyl ether, triethylene glycol ethyl Examples include methyl ether, triethylene glycol ethyl propyl ether, triethylene glycol methyl propyl ether, dipropylene glycol methyl ether acetate, n-nonyl alcohol, diethylene glycol mono-n-butyl ether, triethylene glycol monomethyl ether, ethylene glycol 2-ethylhexyl ether, triethylene glycol monoethyl ether, diethylene glycol monohexyl ether, triethylene glycol monobutyl ether, diethylene glycol mono-2-ethylhexyl ether, tripropylene glycol mono-n-butyl ether, butyl cellosolve acetate, γ-butyrolactone, etc., and one or more selected from these can be used in combination.

[0067] Furthermore, the organic solvent used among the above has an SP value of 26 MPa. 1 / 2 The following is preferable, with an SP value of 17 MPa. 1 / 2 Above 24 MPa 1 / 2 More preferably, the SP value is 18 MPa. 1 / 2 More than 23MPa 1 / 2 It is even more preferable that the following SP value for the organic solvent is 17 MPa. 1 / 2 The above is preferable. By selecting such an organic solvent, the orientation of the metal pigment on the recording medium can be improved, and as a result, the gloss of the image may be improved.

[0068] Furthermore, the SP value is 26 MPa 1 / 2 The content of the following organic solvents is preferably 90% by mass or more, more preferably 95% by mass or more, and more preferably 97% by mass or more, based on 100% by mass of the total mass of the organic solvents. The upper limit is 100% by mass or less. The SP value is 26 MPa. 1 / 2 When the content of the following organic solvents is greater than or equal to the above range, an ink containing metal particles whose surface has been treated with the compound represented by formula (1) or formula (2) and the polyoxyalkyleneamine compound represented by formula (3) is more preferable because it exhibits superior dispersion stability and other characteristics.

[0069] In this specification, the solubility parameter (SP value) is the value obtained by the Okitsu method (unit: MPa). 1 / 2 The Okitsu method is one of the conventionally known methods for calculating SP values, and is described in detail, for example, in the Journal of the Adhesion Society of Japan, Vol. 29, No. 6 (1993), pp. 249-259.

[0070] Furthermore, among the above organic solvents, it is more preferable to select from glycol ether-based organic solvents or lactone-based organic solvents, with glycol ether-based organic solvents being more preferable. Examples of glycol ether-based organic solvents include glycol monoether and glycol diether, with glycol diether being preferred. In particular, it is even more preferable to include one or more selected from diethylene glycol diethyl ether, ethylene glycol ethyl methyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, and γ-butyrolactone.

[0071] The lower limit of the content of organic solvents in the inkjet ink composition is not particularly limited, but is preferably 50.0% by mass, more preferably 60.0% by mass, and even more preferably 70.0% by mass. The upper limit of the content of organic solvents in the inkjet ink composition is also not particularly limited, but is preferably 99.8% by mass, more preferably 99.5% by mass, and even more preferably 99.0% by mass. It is also preferable to set the content of glycol ether-based organic solvents within the above-mentioned ranges.

[0072] 1.4. Other ingredients The inkjet ink composition of this embodiment may contain components other than those described above. Examples of such components include leveling agents, binders, polymerization accelerators, polymerization inhibitors, photopolymerization initiators, dispersants, surfactants, penetration enhancers, humectants, colorants, fixatives, fungicides, preservatives, antioxidants, chelating agents, thickeners, sensitizers, and the like.

[0073] The binder can be any resin, but acrylic resins, ester resins, and urethane resins are preferred, with acrylic resins being more preferred. When a binder is included, it is preferable that the composition contains 0.1% by mass or more, preferably 1% by mass or less, and preferably 0.5% by mass or less.

[0074] Preferred surfactants include silicone-based surfactants, fluorine-based surfactants, and acetylene glycol-based surfactants, with silicone-based surfactants being particularly preferred. When a surfactant is included, it is preferable that the composition contains 0.1% by mass or more, preferably 1% by mass or less, and preferably 0.5% by mass or less.

[0075] Furthermore, the inkjet ink composition may contain a small amount of water in addition to the organic solvent described above. However, the water content in the inkjet ink composition is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.1% by mass or less.

[0076] 1.5. Physical properties of inkjet ink compositions The viscosity of the inkjet ink composition is measured using a vibrating viscometer in accordance with JIS Z 8809. The upper limit of the viscosity of this inkjet ink composition at 20°C is not particularly limited, but is preferably 25 mPa·s, more preferably 15 mPa·s, and even more preferably 10 mPa·s or less, and more preferably 5 mPa·s or less. The lower limit of the viscosity of the inkjet ink composition at 20°C is not particularly limited, but is more preferably 1 mPa·s. This allows for more favorable droplet ejection by the inkjet method.

[0077] 2. Recording Method The recording method according to this embodiment includes a step of attaching the above-described inkjet ink composition to a recording medium. This makes it possible to provide a recording method that can record a recording material with excellent ejection stability, excellent ink dispersion stability, and excellent gloss.

[0078] Examples of recording media include ink-absorbing materials such as paper and fabric. This refers to a recording medium whose recording surface readily absorbs ink. Examples of paper include ordinary paper, inkjet-specific paper, and corrugated cardboard. As for fabrics, natural fibers such as cotton, polyester, and wool, as well as synthetic fibers and nonwoven fabrics, can be used.

[0079] Furthermore, the recording medium may be a non-absorbent recording medium made of plastic material, metal, glass, ceramics, wood, etc. This is a recording medium in which the recording surface does not easily absorb ink. Examples of recording media made of plastic material include plastic films and plastic sheets. Examples of plastics, though not limited to them, include polyvinyl chloride, polyester, and polyolefin. Examples of polyester include polyethylene terephthalate.

[0080] In addition, low-absorption recording media may be used. These are recording media whose recording surface has the second lowest absorption rate after non-absorbent recording media. Examples of low-absorption recording media include those having a coating layer (receiving layer) on the surface for receiving liquid, such as printing paper if the substrate is paper. The coating layer is one that does not easily absorb ink, and examples include those coated with particles such as inorganic compounds together with a binder.

[0081] Low-absorbent or non-absorbent recording media are recording media that do not absorb liquid at all or absorb very little liquid. For example, a non-absorbent or low-absorbent recording media is defined as "a recording medium that does not absorb liquid at all or very little liquid in the Bristow method from the start of contact for 30 msec." 1 / 2 Up to 10 mL / m² of water absorption capacity 2 A recording medium that is one of the following is preferred.

[0082] The Bristow method is the most widely used method for measuring liquid absorption in a short time and is also adopted by the Japan Paper & Pulp Technology Association (JAPAN TAPPI). Details of the test method are described in standard No. 51 "Paper and cardboard - Liquid absorbency test method - Bristow method" of the "JAPAN TAPPI Paper & Pulp Test Methods 2000 Edition".

[0083] In contrast, absorbent recording media refer to recording media that do not fall under the categories of non-absorbent or low-absorbent.

[0084] Furthermore, the shape of the recording medium is not particularly limited and may be any form, such as a sheet, plate, or object.

[0085] When ejecting an ink composition using an inkjet method, the inkjet method may include a piezo method or a method that ejects ink by generating bubbles from heating the ink. While it is possible to do so, the piezo method is preferred from the viewpoint of preventing deterioration of the metal pigments.

[0086] The ink composition can be ejected by the inkjet method using a known droplet ejection device.

[0087] The colored portion formed by the ink composition may, for example, have a predetermined pattern, or it may be formed over the entire surface of the object to be treated.

[0088] 2.1. Primary heating process The recording method according to this embodiment may include a primary heating step, which is a step of heating the ink composition adhering to the recording medium at an early stage. The primary heating step is a step of heating and drying the ink adhering to the recording medium at an early stage. The primary heating step is a heating step to dry at least a portion of the liquid medium of the ink adhering to the recording medium to the extent that the flow of the ink is reduced. The primary heating step may be performed so that the ink adheres to the heated recording medium, or it may be performed to heat the ink at an early stage after adhesion. It is preferable that heating of ink droplets that have landed on the recording medium begins no later than 0.5 seconds after the ink droplets land.

[0089] The primary heating step is preferably performed by using an IR heater, microwave radiation, a platen heater, or blowing warm air onto the recording medium using a fan.

[0090] The heating in the primary heating step can be performed before the ink adhesion step, simultaneously with the adhesion step, or shortly after the adhesion step, and it is preferable that it be performed simultaneously. The ink adhesion step can be carried out with this heating sequence. In particular, it is preferable to heat the recording medium and then adhere the ink composition to the heated recording medium by the ink adhesion step.

[0091] Having a primary heating step is preferable because it allows the ink composition to dry rapidly on the recording medium, thereby suppressing ink bleeding.

[0092] In the primary heating step where the ink composition is heated, the surface temperature of the recording surface of the recording medium is preferably 30°C or higher. On the other hand, 60°C or lower is preferable. Furthermore, 35°C to 55°C is preferable, and even more preferably 40°C to 50°C. When the surface temperature of the recording medium is as described above, it is preferable to have better prevention of bleeding and ejection stability. The recording medium surface temperature in the primary heating process is either the surface temperature of the recording medium when the ink is applied, or, if heating is performed after application, the temperature of the recording medium at the time of heating. It is also the highest temperature during recording.

[0093] 2.2. Post-heating process The recording method according to this embodiment may include a post-heating step (secondary heating step) for heating the recording medium after the ink adhesion step. The post-heating step is a heating step that heats the recording medium sufficiently to complete the recording and allow the recorded material to be used. The post-heating step is a heating step for thoroughly drying the solvent components of the ink. It is preferable that the post-heating step be started more than 0.5 seconds after the ink has adhered to the recording medium. For example, it is preferable to start heating a recording area of ​​the recording medium more than 0.5 seconds after the adhesion of ink to that area is completely finished.

[0094] The heating of the recording medium in the post-heating step can be carried out, for example, using an appropriate heating means. In this case, the surface temperature of the recording medium is preferably 40°C or higher, more preferably 45°C or higher, and even more preferably 50°C or higher. There is no upper limit, but it is preferably 120°C or lower, and more preferably 75°C or lower, 70°C or lower, or 60°C or lower. Furthermore, the heating temperature is preferably below the softening point of the recording medium's substrate.

[0095] 3. Recording device As an example of a recording device that performs the recording method of this embodiment, one can be described as a device that includes a recording head that ejects an ink composition containing a metal pigment and adheres it to a recording medium, and a recording head that ejects the colored ink and adheres it to the recording medium, and performs recording by the recording method described above.

[0096] 3.1. Outline of the device configuration Figure 1 is a schematic cross-sectional view illustrating a recording device. As shown in Figure 1, the inkjet recording device 1 comprises a recording head 2, an IR heater 3, a platen 4, a heating element 5, a cooling fan 6, a preheater 7, and a ventilation fan 8. The recording head is mounted on a carriage (not shown) and performs a main scan in the front-back direction in the figure to adhere ink to the recording medium M. The platen 4 is also provided with a platen heater (not shown). The recording device 1 includes a control unit (not shown) that controls each part to perform recording. The recording head 2 receives ink from an ink reservoir (not shown).

[0097] 3.2. Configuration related to the inkjet head The inkjet head, recording head 2, records onto the recording medium M by ejecting an ink composition from its nozzles. As shown in Figure 1, recording head 2 is a serial recording head that scans the recording medium M multiple times in the main scanning direction relative to the recording medium M to deposit ink onto the recording medium M. Recording head 2 is mounted on a carriage (not shown). Recording head 2 is scanned multiple times in the main scanning direction relative to the recording medium M by the operation of a carriage movement mechanism that moves the carriage in the media width direction of the recording medium M (back-to-front direction in the figure). The media width direction is the main scanning direction of recording head 2. Scanning in the main scanning direction is also called main scanning.

[0098] Here, the main scanning direction is the direction in which the carriage equipped with the recording head 2 moves. In Figure 1, this direction intersects with the sub-scanning direction, which is the transport direction of the recording medium M indicated by arrow SS. Recording is then performed on the recording medium M by repeatedly performing the main scan of the recording head 2 and the sub-scan, which is the transport of the recording medium M.

[0099] Conventional methods can be used for ejecting ink droplets from the recording head 2. For example, a method that uses the vibration of a piezoelectric element to eject droplets, that is, an ejection method that forms ink droplets by the mechanical deformation of an electrostrictive element, can be used.

[0100] 3.3.Primary heating mechanism The inkjet recording device 1 may be equipped with a primary heating mechanism that performs a primary heating process to heat the recording medium M when ejecting ink from the recording head 2 and adhering it to the recording medium. The primary heating mechanism can be of the conduction type, blower type, or radiation type. The conduction type conducts heat to the recording medium from a component in contact with the recording medium. An example is a platen heater. Although not shown, the platen heater is provided integrally with the platen 4. The blower type sends ambient temperature air or warm air to the recording medium to dry the ink. An example is a blower fan. The radiation type heats the recording medium by radiating heat-generating radiation onto it. An example is IR radiation. Although not shown, a heater similar to the platen heater may be provided immediately downstream of the platen 4 in the SS direction. These primary heating mechanisms may be used individually or in combination.

[0101] For example, the primary heating mechanism includes an IR heater 3 and a platen heater.

[0102] Furthermore, when using the IR heater 3, the recording head 2 emits infrared radiation, which is used for radiant recording. The recording medium M can be heated. This also makes it easier for the recording head 2 to be heated at the same time, but the temperature can be raised without being affected by the thickness of the recording medium M, compared to when it is heated from the back surface of the recording medium M, such as by a platen heater. The primary heating mechanism may also include various fans (e.g., ventilation fan 8) that blow warm air or air at the same temperature as the environment onto the recording medium M to dry the ink on the recording medium M.

[0103] The platen heater can heat the recording medium M via the platen 4 at a position facing the recording head 2. The platen heater is capable of heating the recording medium M by conduction and is used as needed in inkjet recording methods.

[0104] Furthermore, the inkjet recording device 1 may be equipped with a preheater 7 that preheats the recording medium M before ink is applied to the recording medium M.

[0105] 3.4. Post-heating mechanism The system may also include a post-heating mechanism that performs a post-heating step after the white ink application step and the non-white ink application step to heat the recording medium, dry the ink, and fix it in place.

[0106] The heating element 5 used in the post-heating mechanism dries and solidifies the ink adhering to the recording medium M. When the heating element 5 heats the recording medium M on which the image is recorded, moisture and other substances contained in the ink evaporate more quickly, and an ink film is formed by the resin contained in the ink. In this way, the ink film firmly fixes or adheres to the recording medium M, resulting in excellent film-forming properties, and a high-quality image can be obtained in a short time.

[0107] 3.5. Other Configurations The inkjet recording device 1 may have a cooling fan 6. After the ink recorded on the recording medium M dries, the ink on the recording medium M is cooled by the cooling fan 6, thereby forming an ink coating film with good adhesion on the recording medium M.

[0108] The recording device shown in Figure 1 is a serial printer that performs recording using a so-called serial method. The recording device may also be a line printer equipped with a line head that performs recording using a line method.

[0109] The line head has a nozzle row in which multiple nozzles are arranged in the width direction of the recording medium, and has a length greater than or equal to the width of the recording medium M being transported, allowing an image to be recorded on the transported recording medium M in the width direction of the recording medium all at once. Recording can be performed in a single scan. Alternatively, after performing one scan by transporting the recording medium, it is possible to perform recording with two or more scans by returning the recording medium in the reverse direction of transport and transporting it again for another scan.

[0110] The scanning may be performed by a head whose position is fixed relative to the transported recording medium, or by a head that moves while scanning is performed relative to the recording medium fixed in the platen area.

[0111] Furthermore, a recording device capable of line-type recording can be configured similarly to the one shown in Figure 1, except that the recording head 2 is replaced with a line head. Specifically, the heating mechanisms such as the ventilation fan 8, IR heater 3, platen heater, and preheater 7, which are located above the recording head 2 in Figure 1, can be similarly provided above or below the line head. Alternatively, a post-heating mechanism such as the heating heater 5 and cooling fan 6 shown in Figure 1 may also be provided.

[0112] 4. Examples and Comparative Examples The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. It is not meant to be done. Unless otherwise specified, percentages below refer to mass.

[0113] 4.1. Preparation of inkjet ink composition First, a 20 μm thick polyethylene terephthalate film with a smooth surface and a surface roughness Ra of 0.02 μm or less was prepared. Next, a release layer was formed on the entire surface of one side of this film by coating it with a release resin solubilized with acetone using a roll coater. The polyethylene terephthalate film with the release layer was transported into a vacuum deposition apparatus at a speed of 5 m / s, and a 16 nm thick film composed of Al was formed under reduced pressure.

[0114] Next, a polyethylene terephthalate film with an Al membrane formed on it was immersed in tetrahydrofuran, and ultrasonic vibrations at 40 kHz were applied to obtain a dispersion of Al metal particles.

[0115] Next, tetrahydrofuran was removed using a centrifuge, and diethylene glycol diethyl ether was added to obtain a suspension with a metal particle content of 5% by mass.

[0116] Next, this suspension was processed using a circulating high-power ultrasonic grinder to grind the metal particles to a predetermined size. This process involved applying 20 kHz ultrasound.

[0117] Next, the suspension was subjected to heat treatment at 55°C for 2 hours under 40 kHz ultrasonic irradiation to disperse the aggregated metal particles in a primary particle state. Then, the treatment agents listed in each table and the compound "poly(EO / PO)amine" represented by formula (3) shown in the table were added in a ratio to the metal particles such that the mass ratio was as shown in the table.

[0118] Then, by heat treatment at 55°C for 5 hours under 28kHz ultrasonic irradiation, the treatment agent reacted on the surface of the metal particles, and a dispersion of metal pigment surface-modified with the treatment agent was obtained. For confirmation, the organic solvent was separated from the obtained dispersion using a centrifuge, and it was found that the treatment agent was not present in the organic solvent. From this, it is presumed that the treatment agent adheres to the metal particles.

[0119] Subsequently, an organic solvent and a binder were added to the resulting dispersion of metal pigments to obtain the inkjet ink compositions for each example. These were solvent-based compositions.

[0120] When the volume-average particle size of the metal pigment contained in the ink compositions obtained in this way was measured, it was 0.25 μm for all but Examples 6-9, and the average thickness was 16 nm. The volume-average particle size of the metal pigment in Examples 6-9 was adjusted by changing the processing time in a circulating high-power ultrasonic grinder.

[0121] The composition of the metal pigments contained in the ink compositions for each example and comparative example is summarized in Tables 1 to 3. The details of each component are described below.

[0122] • Tridecyl phosphate (Tokyo Chemical Industries) • Tetradecyl phosphate (Tokyo Chemical Industries) Octadecyl phosphonate (Tokyo Chemical Industries) • Dodecylphosphonic acid (Tokyo Chemical Industries) • Stearyl phosphate (Tokyo Chemical Industries) • Tetracosyl phosphate (Tokyo Chemical Industries) Octadecyltrimethoxysilane (Tokyo Chemical Industries) FAS13: 1H,1H,2H,2H-perfluorooctyltrimethoxysilane • FHP: 2-(perfluorohexyl)ethylphosphonic acid (Tokyo Chemical Industries) • SURFONAMINE L-200: A polyoxyalkyleneamine compound represented by formula (3), with an average m / (m+n) × 100 (%) of 91%, manufactured by Huntsman. • SURFONAMINE L-100: A polyoxyalkyleneamine compound represented by formula (3), with an average m / (m+n) × 100 (%) of 86%, manufactured by Huntsman. • SURFONAMINE L-207: A polyoxyalkyleneamine compound represented by formula (3), with an average m / (m+n) × 100 (%) of 77%, manufactured by Huntsman. • SURFONAMINE B-200: A polyoxyalkyleneamine compound represented by formula (3), with an average m / (m+n) × 100 (%) of 17%, manufactured by Huntsman. • SURFONAMINE B-600: A polyoxyalkyleneamine compound represented by formula (3), with an average m / (m+n) × 100 (%) of 10%, manufactured by Huntsman. • SURFONAMINE FL-1000: A polyoxyalkyleneamine compound represented by formula (3), wherein the average m / (m+n) × 100 (%) is 0%, manufactured by Huntsman. All of the polyoxyalkyleneamine compounds represented by formula (3) above had a weight-average molecular weight of 600 to 3000. • DEDG: Diethylene glycol diethyl ether, SP value = 17.9 MPa 1 / 2 • MEDG: Diethylene glycol monoethyl ether, SP value = 18.2 MPa 1 / 2 BTGH: Tetraethylene glycol monobutyl ether, SP value = 20.6 MPa 1 / 2 • γBL: γ-butyrolactone, SP value = 23.1 MPa 1 / 2 • PG: Propylene glycol, SP value = 28.7 MPa 1 / 2 • Paraloid B60: Binder (acrylic resin, manufactured by Dow Chemical)

[0123] Regarding the metallic pigments, the volume-average particle size D (D50) in the table was measured using a Microtrac MT-3300 (Microtrac-Bell, a laser diffraction / scattering particle size distribution analyzer). In addition, the viscosity of the ink compositions of each example at 25°C, measured using a rotational viscometer in accordance with JIS Z8809, was within the range of 1.5 mPa·s to 15 mPa·s.

[0124] [Table 1]

[0125] [Table 2]

[0126] [Table 3]

[0127] 4.2. Evaluation Method 4.2.1. Record Test A recording device was prepared. A modified version of the Seiko Epson SC-S80650 was used. The nozzle density of the inkjet head nozzle row was set to 360 npi and 360 nozzles. Ink was filled into the inkjet head. The drive waveform of the inkjet head was optimized to ensure optimal ejection of the filled ink. During recording, the platen heater was controlled to maintain a surface temperature of 40°C on the recording medium on the platen during the primary heating process. During recording, an after-heater was activated to perform a post-heating process, and the surface temperature of the recording medium during the post-heating process was set to 50°C. For recording, a polyvinyl chloride film (Mactac5829R, manufactured by Mactac Corporation) was used as the recording medium. The amount of ink adhering to the recording pattern during recording is 3 mg / inch. 2 , recording resolution The resolution was set to 1440 x 1440 dpi. A recording test was then conducted.

[0128] 4.2.2. Dispersion stability (long-term storage) Ink packs containing the inkjet ink compositions of each example and comparative example were stored at 65°C for 15 days. The percentage increase in the average particle size after storage compared to the average particle size before storage was examined. The results were evaluated according to the following criteria and are shown in the table. A: The growth rate is less than 1%. B: Growth rate is between 1% and 2%. C: Growth rate is between 2% and 4%. D: Growth rate is between 4% and 6%. E: Growth rate exceeds 6%.

[0129] 4.2.3. Gloss Evaluation The gloss of the recording portion of each example recording obtained in the above recording test was measured at a tilt angle of 60° using a MINOLTA MULTI GLOSS 268A gloss meter and evaluated according to the following criteria. A higher value indicates superior gloss. A: Glossiness of 450 or higher B: Glossiness level between 400 and 450 C: Glossiness is between 350 and 400 D: Glossiness is between 300 and 350 E: Glossiness is less than 300

[0130] 4.2.4. Assessment of subsidence The inkjet inks obtained in each example and comparative example were stored in containers at room temperature for two months. Afterward, they were visually evaluated according to the following criteria, and the results are recorded in the table. A: No sedimentation of metallic pigments is observed. B: Some sedimentation of metallic pigments is observed. C: Sedimentation of the metallic pigment was observed, but after shaking the container 10 times, the sedimentation stopped. D: Sedimentation of the metallic pigment was observed, and sedimentation was still present even after shaking the container 10 times.

[0131] 4.3. Evaluation Results Each example of the solvent-based inkjet ink composition, containing a metal pigment surface-treated with a compound represented by formula (1) or formula (2), a polyoxyalkyleneamine compound containing a compound represented by formula (3), and an organic solvent, wherein the compound represented by formula (3) has an average concentration of 20% or more (m / (m+n) × 100%), was found to have good dispersibility and produce records with excellent gloss.

[0132] The embodiments and variations described above are merely examples and are not limiting. For example, each embodiment and each variation can be combined as appropriate.

[0133] The present invention includes configurations substantially identical to those described in the embodiments, for example, configurations with the same function, method, and results, or configurations with the same purpose and effect. Furthermore, the present invention includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. Furthermore, the present invention includes configurations that produce the same effects or achieve the same purpose as those described in the embodiments. Finally, the present invention includes configurations that add known technology to the configurations described in the embodiments.

[0134] The following can be derived from the embodiments and modifications described above.

[0135] Inkjet ink composition, A solvent-based inkjet ink composition, It contains a metal pigment, a polyoxyalkyleneamine compound, and an organic solvent. The aforementioned metal pigment is a metal particle whose surface has been treated with a surface treatment agent. The surface treatment agent is a compound represented by the following formula (1) or formula (2), The polyoxyalkyleneamine compound includes a compound represented by the following formula (3): The compound represented by formula (3) above has an average m / (m+n) × 100 (%) of 20% or more. (R 1 -)P(O)(OH)2···(1) (R 2 -O-) a P(O)(OH) 3-a ...(2) (In equations (1) and (2), R 1 , R 2 (where a independently represents a hydrocarbon group having 14 or more carbon atoms, which may be substituted with substituents, and a represents 1 or 2.) R 3 (OC2H4) m -(OC3H6) n -NH2···(3) (In formula (3), R 3 ∫ represents a hydrogen atom or an alkyl group having 4 or fewer carbon atoms, m represents an integer of 1 or more, n represents an integer of 0 or more, and m+n represents an integer of 10 or more. However, the order of the oxyethylene unit (OC2H4) and the oxypyroprene unit (OC3H6) is arbitrary.

[0136] This inkjet ink composition allows for the production of records with good water resistance and excellent dispersibility of metallic pigments, as well as good gloss.

[0137] In the above inkjet ink composition, The compound represented by formula (3) may be present in an amount of 20% to 80% by mass, based on 100% by mass of the total mass of the metal particles.

[0138] This inkjet ink composition also exhibits excellent dispersibility of metal pigments.

[0139] In the above inkjet ink composition, The volume-average particle size D50 of the metal pigment may be 0.5 μm or less.

[0140] This inkjet ink composition is more suitable for inkjet printing.

[0141] In the above inkjet ink composition, The metal pigment may be in the form of flakes, and the average thickness of the metal pigment may be 30 nm or less.

[0142] This inkjet ink composition allows for the formation of images with even better metallic luster.

[0143] In the above inkjet ink composition, For a total mass of 100% of the organic solvent, the SP value is 26 MPa. 1 / 2 The following organic solvents may be present in an amount of 90% by mass or more.

[0144] This inkjet ink composition also exhibits excellent dispersibility of metal pigments.

[0145] In the above inkjet ink composition, The aforementioned organic solvent is selected from glycol ether-based organic solvents or lactone-based organic solvents, in an inkjet ink composition.

[0146] In the above inkjet ink composition, The organic solvent may be present in an amount of 50% by mass or more relative to the total amount of the inkjet ink composition.

[0147] In the above inkjet ink composition, The aforementioned R 1 and R 2 This may be an unsubstituted hydrocarbon group.

[0148] This inkjet ink composition further enhances the water resistance of the metal pigments.

[0149] In the above inkjet ink composition, The aforementioned R 1 and R 2This may be a hydrocarbon group having 15 to 30 carbon atoms.

[0150] This inkjet ink composition further enhances the water resistance of the metal pigments.

[0151] In the above inkjet ink composition, The aforementioned metal particles may consist of aluminum or an aluminum alloy.

[0152] This inkjet ink composition allows for the creation of images with even better metallic luster.

[0153] The recording method comprises the step of applying the above-mentioned inkjet ink composition to a recording medium.

[0154] This recording method allows for the formation of a coating film with good water resistance and gloss. [Explanation of Symbols]

[0155] 1... Inkjet recording device, 2... Recording head, 3... IR heater, 4... Platen, 5... Heating heater, 6... Cooling fan, 7... Preheater, 8... Ventilation fan

Claims

1. It contains a metal pigment, a polyoxyalkyleneamine compound, and an organic solvent. The aforementioned metal pigment is a metal particle whose surface has been treated with a surface treatment agent. The surface treatment agent is a compound represented by the following formula (1) or formula (2), The polyoxyalkyleneamine compound includes a compound represented by the following formula (3): The compound represented by formula (3) above has an average m / (m+n) × 100 (%) of 20% or more. The volume-average particle size D50 of the aforementioned metal pigment is 50 nm or more and 400 nm or less. An inkjet ink composition, which is a solvent-based ink. (R １ -)P(O)(OH) ２ ・・・(1) (R ２ -O-) ａ P(O)(OH) ３－ａ ・・・(2) (In equations (1) and (2), R １ , R ２ (where a independently represents a hydrocarbon group having 16 or more carbon atoms, which may be substituted with substituents, and a represents 1 or 2.) R ３ (OC ２ H ４ ) ｍ -(OC ３ H ６ ) ｎ -NH ２ ・・・(3) (In formula (3), R ３ represents a hydrogen atom or an alkyl group having 4 or fewer carbon atoms, m represents an integer of 1 or more, n represents an integer of 0 or more, and m+n represents an integer of 10 or more. However, oxyethylene units (OC ２ H ４ ) and oxypyroprene unit (OC ３ H ６ The order of the elements is arbitrary.

2. In claim 1, The compound represented by formula (3) is present in an inkjet ink composition in an amount of 20% by mass or more and 80% by mass or less, based on 100% by mass of the total mass of the metal particles.

3. In claim 1 or claim 2, An inkjet ink composition wherein the volume-average particle diameter D50 of the metal pigment is 100 nm or more and 400 nm or less.

4. In any one of claims 1 to 3, The metal pigment is in the form of flakes, and the average thickness of the metal pigment is 30 nm or less. Inkjet ink composition.

5. In any one of claims 1 to 4, The SP value is 26 MPa relative to 100% by mass of the total organic solvent. １／２ An inkjet ink composition containing 90% by mass or more of the following organic solvents.

6. In any one of claims 1 to 5, The aforementioned organic solvent is selected from glycol ether-based organic solvents or lactone-based organic solvents, in an inkjet ink composition.

7. In any one of claims 1 to 6, The inkjet ink composition contains the organic solvent in an amount of 50% by mass or more relative to the total amount of the inkjet ink composition.

8. In any one of claims 1 to 7, The aforementioned R １ and R ２ This is an inkjet ink composition in which the hydrocarbon group is unsubstituted.

9. In any one of claims 1 to 8, The aforementioned R １ and R ２ This is an inkjet ink composition comprising a hydrocarbon group having 16 to 30 carbon atoms.

10. In any one of claims 1 to 9, The aforementioned metal particles are made of aluminum or an aluminum alloy, and the inkjet ink composition is such that the metal particles are made of aluminum or an aluminum alloy.

11. A recording method comprising the step of adhering an inkjet ink composition according to any one of claims 1 to 10 to a recording medium.

Images