Inkjet ink composition and recording method

Abstract

Provided are an inkjet ink composition and a recording method having excellent water resistance and metallic gloss of recorded objects. An inkjet ink composition according to one embodiment of the present invention is a solvent-based ink containing a metallic pigment and an organic solvent, wherein the metallic pigment is a metal particle whose surface is treated with a surface treatment agent, wherein the surface treatment agent contains a compound represented by the general formula (1) and a compound represented by the general formula (2), and the mass ratio of the compound represented by the general formula (2) to the total of the compound represented by the general formula (1) and the compound represented by the general formula (2) is 45% by mass or less. (R‑O‑)P(O)(OH)2…(1)(R‑O‑)2P(O)(OH)…(2)(wherein R is independently a hydrocarbon group having 8 or more carbon atoms).

Description

Technical Field

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

[0002] The inkjet recording method can record high-definition images with a relatively simple device, and has achieved rapid development in various aspects. Among them, a recorded object with a metallic luster formed by metal printing has been proposed, and ink with a metallic luster has been developed. For example, Patent Document 1 discloses an ink composition using a metal pigment surface-treated with a fluorine-based compound.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2015-189775.

[0006] However, water resistance and metallic gloss of recorded objects are still insufficient. Summary of the invention

[0007] One embodiment of the inkjet ink composition according to the present invention comprises:

[0008] The inkjet ink composition is a solvent-based ink containing a metal pigment and an organic solvent.

[0009] The metallic pigment is a metal particle whose surface is treated with a surface treatment agent.

[0010] The surface treatment agent contains a compound represented by the general formula (1) and a compound represented by the general formula (2), wherein the mass ratio of the compound represented by the general formula (2) to the total of the compound represented by the general formula (1) and the compound represented by the general formula (2) is 45 mass % or less.

[0011] (RO-)P(O)(OH)2......(1)

[0012] (RO-)2P(O)(OH)......(2)

[0013] (In the formula, R is independently a hydrocarbon group having 8 or more carbon atoms.)

[0014] In one embodiment of the recording method according to the present invention,

[0015] The method includes a step of ejecting the inkjet ink composition of one embodiment described above by an inkjet method to allow the inkjet ink composition to adhere to a recording medium. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1This is a schematic diagram of an example of a recording device that can be used for the recording method involved in the present invention.

[0017] Explanation of symbols

[0018] 1. Inkjet recording device; 2. Recording head; 3. IR heater; 4. Press plate; 5. Heater; 6. Cooling fan; 7. Preheater; 8. Ventilation fan. DETAILED DESCRIPTION

[0019] The following describes the embodiments of the present invention. The embodiments described below illustrate examples of the present invention. The present invention is not limited to the following embodiments, but also includes various modifications implemented within the scope of the present invention. It should be noted that the structures described below are not necessarily all necessary structures of the present invention.

[0020] 1. Inkjet ink composition

[0021] An inkjet ink composition according to one embodiment of the present invention is a solvent-based ink containing a metallic pigment and an organic solvent, wherein the metallic pigment is a metal particle whose surface is treated with a surface treatment agent, wherein the surface treatment agent contains a compound represented by the general formula (1) and a compound represented by the general formula (2), and the mass ratio of the compound represented by the general formula (2) to the total of the compound represented by the general formula (1) and the compound represented by the general formula (2) is 45 mass % or less.

[0022] (RO-)P(O)(OH)2……(1)

[0023] (RO-)2P(O)(OH)……(2)

[0024] (In the formula, R is independently a hydrocarbon group having 8 or more carbon atoms.)

[0025] In the past, in order to obtain water resistance and floatation (to arrange the metal pigments appropriately near the outer surface of the printed layer), etc., metal pigments such as aluminum were surface treated with fluorine-based surface treatment agents. However, metal pigments surface treated with such fluorine-based surface treatment agents are still insufficient in terms of water resistance, dispersion stability and the metallic gloss of the records related to them. For example, during the long-term storage of ink, due to the trace amount of water contained in the ink and the water intruding from the outside, the metal pigments (especially aluminum pigments) are oxidized, hydrogen is generated, and the storage stability of the ink deteriorates. In addition, in this case, due to the oxidation of the metal pigments, the glossiness also deteriorates. In particular, when the record is exposed to a high humidity environment, the deterioration of the glossiness is more significant.

[0026] Therefore, the inventors of the present invention have conducted in-depth research and found that when a diester and a monoester of a specific alkyl phosphate are used as surface treatment agents for metal pigments, and these diesters and monoesters are in a predetermined range of content ratios, excellent water resistance (moisture resistance) can be obtained, and the persistence of gloss and storage stability are also excellent. The monoester has a small steric hindrance, so it is easy to uniformly treat the surface of the metal pigment, and in particular, the dispersion stability and gloss of the metal pigment can be excellent. On the other hand, the diester makes it difficult for water to approach the surface of the metal pigment due to its large steric hindrance, and in particular, the water resistance can be excellent. By containing the diester and the monoester with different properties in a predetermined range of content ratios, a balance between water resistance and gloss can be achieved, making both excellent. In addition, the inkjet ink composition involved in this embodiment does not require the use of the aforementioned fluorine-based surface treatment agent, so it is also advantageous from the perspective of environmental correspondence.

[0027] The inkjet ink composition involved in this embodiment is a solvent-based ink. Here, "solvent-based" in the present invention refers to an ink composition containing an organic solvent as the main solvent component. The content of water in the solvent-based ink composition is preferably 3.0% by mass or less, more preferably 1.0% by mass or less, further preferably 0.5% by mass or less, particularly preferably 0.1% by mass or less, and more particularly preferably 0.01% by mass or less, with a lower limit of 0% by mass. In addition, the content of water relative to the total amount of the inkjet ink composition may also be within the above range.

[0028] The inkjet ink composition according to the present embodiment is an ink containing a metallic pigment, and is an ink capable of recording an image having a metallic gloss due to the metallic pigment on a recording medium. Such an ink is also referred to as a metallic ink or a metallic glittering ink. It should be noted that when an excellent gloss is obtained by using the inkjet ink composition according to the present embodiment, the gloss is sometimes referred to as a metallic gloss.

[0029] The ink composition used in the inkjet method is referred to as an inkjet ink composition. The inkjet method refers to a recording method in which droplets of ink or the like are ejected from the nozzles of an inkjet head of an inkjet recording device or the like and applied to a recording medium.

[0030] It should be noted that, in this specification, when the compound represented by the general formula (1) and the compound represented by the general formula (2) are not particularly distinguished, both are also collectively referred to as "specific alkyl phosphate". In addition, the compound represented by the general formula (1) is also referred to as "monoester" or "monomer", and the compound represented by the general formula (2) is also referred to as "diester" or "dimer".

[0031] Hereinafter, each component contained in the inkjet ink composition according to the present embodiment will be described. It should be noted that the inkjet ink composition may also be referred to as an "ink composition" or "ink".

[0032] 1.1 Metallic Pigments

[0033] The inkjet ink composition involved in this embodiment contains a metallic pigment, which is a metal particle whose surface is treated by a surface treatment agent. More specifically, it is speculated that the phosphoric acid group-containing portion of the surface treatment agent of the metallic pigment is chemically bonded to the surface of the metal particle. At this time, the surface treatment agent itself is not limited to being bonded to the surface of the metal particle through hydrogen bonds and intermolecular forces, and can be a metal particle with a residue of the surface treatment agent. That is, it can be considered that in the metallic pigment, the metal particles and the surface treatment agent are bonded by covalent bonds through the reaction of the OH group that may be present on the surface of the metal particle with the phosphoric acid group-containing portion of the surface treatment agent.

[0034] Alternatively, the surface treatment agent may be attached to the surface of the metal particles by physical adsorption, etc. In this way, it is considered that the surface treatment agent is attached to the metal particles by bonding, physical adsorption, etc.

[0035] The lower limit of the content of the metallic pigment is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, further preferably 0.3% by mass or more, and particularly preferably 0.5% by mass or more, relative to the total mass of the inkjet ink composition. The upper limit of the content of the metallic pigment is preferably 10% by mass or less, more preferably 5% by mass or less, further preferably 2.4% by mass or less, particularly preferably 2.2% by mass or less, and particularly preferably 1.8% by mass or less, relative to the total mass of the inkjet ink composition. If the content of the metallic pigment is within the above range, there is a tendency that the storage stability and water resistance of the ink composition can be made better, and the gloss and abrasion resistance of the colored portion formed using the ink composition can be made particularly excellent.

[0036] 1.1.1 Metal particles

[0037] Metal particles are particles in which at least a portion of the visible portion is made of a metal material, and usually the vicinity of the outer surface is made of a metal material. Metal particles are a component that has a significant influence on the appearance of a recorded object produced using an ink composition containing a metal pigment.

[0038] The metal particles may be formed of a metal material as long as at least the area near the surface is formed of a metal material. For example, the metal particles may be formed of a metal material as a whole, or may be metal particles having a base formed of a non-metallic material and a coating formed of a metal material covering the base. In addition, the metal particles may also form an oxide coating such as a passive film on their surface. Even such metal particles have problems such as water resistance and metallic gloss in the past, but by applying the present invention, excellent water resistance and metallic gloss can be obtained.

[0039] As the metal material constituting the metal particles, metals as monomers and various alloys can be used. For example, aluminum, silver, gold, platinum, nickel, chromium, tin, zinc, indium, titanium, iron, copper, and alloys having at least one of these metals can be cited. Among them, the metal particles are preferably composed of aluminum or an aluminum alloy, and more preferably composed of aluminum. As one of the reasons for preferring aluminum and aluminum alloys, it can be cited that the specific gravity is lower than that of metals such as iron. As a result, the sedimentation of the metal pigment dispersed in the ink proceeds very slowly, so there is a tendency to effectively prevent the occurrence of uneven concentration, etc., and at the same time, the ink composition can be stored for a longer period of time.

[0040] In addition, the production cost of the recorded object manufactured by the ink composition containing the metal pigment can be suppressed, and the gloss and high-grade feeling of the recorded object can be made particularly excellent. Aluminum and aluminum alloys originally also show particularly excellent gloss among various metal materials, but when the particles composed of these materials are applied to the ink composition, the inventors found that the following problems will occur. That is, the inventors found that the storage stability (water resistance) of the ink composition is particularly low. In addition, especially when such an ink composition is used as an inkjet composition, it is particularly easy to produce problems such as reduced ejection stability caused by the increase in viscosity caused by gelation. In contrast, even if the metal pigment uses metal particles composed of aluminum or aluminum alloy, when the surface is modified with a specific alkyl phosphate described later, the above problems can be prevented. That is, by the metal particles being composed of aluminum or aluminum alloy, the effect brought by the present invention can be more significantly exerted.

[0041] The metal particles may be in any shape such as spherical, spindle-shaped, or needle-shaped, but are preferably in a scale-like shape.

[0042] Thus, on the treated body to which the ink composition is applied, it is easy to arrange the main surface of the metal particles along the surface shape of the treated body. As a result, there is a tendency that even in the obtained colored body, the glossiness and the like originally possessed by the metal material constituting the metal particles can be more effectively utilized, the glossiness and the high-grade feeling of the colored body can be made particularly excellent, and the abrasion resistance of the colored body can be made particularly excellent. In addition, in an ink composition in which the metal pigment is not surface-modified with a specific alkyl phosphate, if the metal particles are scaly, the storage stability (water resistance) tends to become particularly low, and the ejection stability tends to become particularly low. In addition, the excellent glossiness and the like brought by the scaly metal particles cannot be exhibited.

[0043] On the other hand, when the metal pigment is a pigment in which the surface of the metal particles is modified with a specific alkyl phosphate, as in the inkjet ink composition according to the present embodiment, the above-mentioned problem can be prevented even if the metal particles are flaky. That is, when the metal particles are flaky, the effect of the present invention can be more significantly exerted.

[0044] In the present invention, the scaly shape refers to a shape such as a flat plate shape, a curved plate shape, etc., in which the area when viewed from a predetermined angle, such as when viewed from above, is larger than the area when viewed from an angle perpendicular to the viewing direction. In particular, when viewed from the direction with the largest projected area, that is, the area S1[μm 2 ] and the area S0 [μm] when observed from the direction with the largest area when observed from the direction orthogonal to the observation direction 2 ] The ratio S1 / S0 is preferably 2 or more, more preferably 5 or more, and further preferably 8 or more. It is further preferably 10 or more, and further preferably 20 or more. It is further preferably 30 or more. The upper limit of S1 / S0 is not particularly limited, but is preferably 1000 or less, more preferably 500 or less, and further preferably 100 or less. It is further preferably 80 or less.

[0045] As this value, for example, 50 arbitrary particles can be observed and an average value of values ​​calculated for these particles can be adopted. The observation can be performed using, for example, an electron microscope, an atomic force microscope, or the like.

[0046] Alternatively, the volume average particle diameter (D50) and the average thickness described below may be used, and the units may be unified to obtain volume average particle diameter (D50) / average thickness, and this may be used as the above range.

[0047] When the metal particles are flaky, the average thickness of the metal particles is preferably 5 to 90 nm. The lower limit of the average thickness of the metal particles is not particularly limited, but is more preferably 10 nm or more, further preferably 15 nm or more, and particularly preferably 20 nm or more. In addition, when the metal particles are flaky, the upper limit of the average thickness of the metal particles is not particularly limited, but is more preferably 70 nm or less, further preferably 50 nm or less, particularly preferably 30 nm or less, and more particularly preferably 20 nm or less. If the metal particles are flaky and have an average thickness of 5 to 90 nm, preferably an average thickness within the above range, there is a tendency to be able to more significantly exert the effect of the flaky particles.

[0048] It should be noted that the average thickness of the metal particles can be measured using an atomic force microscope (AFM) in the same manner as the average thickness of the metal pigment described later. For example, the average thickness is preferably the arithmetic mean thickness by measuring 50 arbitrary metal particles by atomic force microscopy.

[0049] The preferred range and measurement method of the volume average particle size (D50) of the metal particles may be the same as those of the volume average particle size (D50) of the metallic pigment described later.

[0050] The metal particles can be produced by any method, but when composed of Al, it is preferably obtained by forming a film composed of Al by a vapor phase film forming method and then crushing the film. As a result, the glossiness of Al can be more effectively expressed in the colored portion formed using the ink composition of the present invention. In addition, the deviation of the characteristics between the particles can be suppressed. In addition, by using this method, even relatively thin metal particles can be appropriately produced.

[0051] When such a method is used to manufacture metal particles, for example, by forming a film composed of Al on a substrate, the metal particles can be appropriately manufactured. As the substrate, for example, a plastic film such as polyethylene terephthalate can be used. In addition, the substrate may also have a release agent layer on the film-forming surface.

[0052] The pulverization is preferably performed by applying ultrasonic vibration to the film in a liquid, thereby making it easy to obtain metal particles of the aforementioned particle size and suppressing the occurrence of variations in size, shape, and characteristics among the metal particles.

[0053] In addition, when the pulverization is performed by the above method, as the liquid, a polar compound such as alcohol, hydrocarbon compound, ether compound, propylene carbonate, γ-butyrolactone, N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, cyclohexanone, acetonitrile, etc. can be appropriately used. By using such a liquid, unintentional oxidation of the metal particles can be prevented, and the productivity of the metal particles can be particularly excellent. In addition, the variation in size, shape, and characteristics between the particles can be particularly small.

[0054] Examples of alcohols include methanol, ethanol, propanol, and butanol. Examples of hydrocarbon compounds include n-heptane, n-octane, decane, dodecane, tetradecane, toluene, xylene, isopropyl toluene, durene, indene, dipentene, tetralin, decalin, and cyclohexylbenzene. Examples of ether compounds include ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol methyl ethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, tetraethylene glycol monobutyl ether, diethylene glycol methyl ethyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol n-butyl ether, tripropylene glycol dimethyl ether, triethylene glycol diethyl ether, 1,2-dimethoxyethane, bis(2-methoxyethyl) ether, p-dioxane, and tetrahydrofuran.

[0055] 1.1.2 Surface treatment agent

[0056] The metal pigment contained in the inkjet ink composition involved in this embodiment is a metal particle whose surface is treated by a surface treatment agent, and the surface treatment agent contains a compound represented by the general formula (1) and a compound represented by the general formula (2), and the mass ratio of the compound represented by the general formula (2) to the total of the compound represented by the general formula (1) and the compound represented by the general formula (2) is less than 45 mass%.

[0057] (RO-)P(O)(OH)2……(1)

[0058] (RO-)2P(O)(OH)……(2)

[0059] (In the formula, R is independently a hydrocarbon group having 8 or more carbon atoms.)

[0060] 1.1.2.1 Specific alkyl phosphates

[0061] The compound (monomer) represented by the general formula (1) is a compound obtained by esterifying one of the three hydroxyl groups of phosphoric acid with an R group. Such a monomer has a small steric hindrance, so it is easy to uniformly treat the surface of the metal pigment, and in particular, it can make the dispersion stability and gloss of the metal pigment excellent. The compound (dimer) represented by the general formula (2) is a compound obtained by esterifying two of the three hydroxyl groups of phosphoric acid with an R group. Such a dimer has a large steric hindrance, making it difficult for water to approach the surface of the metal pigment, and in particular, it has excellent water resistance.

[0062] In the above formula, R is a hydrocarbon group having a carbon skeleton with 8 or more carbon atoms, which is a hydrocarbon group having a skeleton with 8 or more carbon atoms bonded continuously. It should be noted that in the general formula (1) and the general formula (2), any carbon atom of the carbon skeleton with 8 or more carbon atoms of R is directly bonded to the oxygen atom of O of (RO-), and the oxygen atom is directly bonded to the phosphorus atom of P.

[0063] Therefore, it is speculated that when the surface treating agent reacts with the metal particles at the hydroxyl group bonded to the phosphorus atom of the surface treating agent to modify the surface of the metal particles, R can be located relatively close to the metal particles, thereby improving the dispersion stability of the metal pigment.

[0064] In addition, it is presumed that when R is a relatively long-chain hydrocarbon group, excellent dispersion stability can be imparted to the metallic pigment.

[0065] As the hydrocarbon group with a carbon skeleton having more than 8 carbon atoms, saturated hydrocarbon groups without double bonds or triple bonds between carbons, unsaturated hydrocarbon groups with double bonds or triple bonds between carbons, etc. can be listed. The hydrocarbon group of R can be an aromatic hydrocarbon group with an aromatic ring structure in the carbon skeleton, a chain or cyclic aliphatic hydrocarbon group, etc. In particular, the dispersion stability of the chain aliphatic hydrocarbon group is more excellent, so it is preferred. The chain aliphatic hydrocarbon group can be a branched type or a straight chain type, and from the viewpoint of being more excellent in dispersion stability, ejection stability, gloss, etc., a straight chain type is preferred. In this case, for example, it can be inferred that since more specific alkyl phosphates can be modified on the surface of the metal particles, a sufficient effect can be achieved.

[0066] R is a hydrocarbon group, and therefore has a bond between a carbon atom and a hydrogen atom. When R has no substituent, R is a hydrocarbon group consisting of carbon atoms and hydrogen atoms. For example, when R is a chain aliphatic hydrocarbon group, alkyl, alkenyl, alkynyl, etc. can be cited. In this case, especially when the ink is a solvent-based ink, the dispersion stability is more excellent, so it is preferred.

[0067] R is a hydrocarbon group having a carbon skeleton with 8 or more carbon atoms, containing carbon atoms and hydrogen atoms, and having at least a bond between carbon atoms and hydrogen atoms. Therefore, R may be a hydrocarbon group having a portion of hydrogen atoms substituted by a substituent, as long as it has at least one unsubstituted hydrogen atom.

[0068] As the substituent, for example, a carboxyl group, a hydroxyl group, an amino group, a group containing an oxyalkylene group, a halogenated group such as a fluoro group, etc. can be cited. In particular, when substituted with a fluoro group, etc., a higher hydrophobicity can be imparted to the metallic pigment, which is more preferred from the viewpoint of water resistance and gloss. It should be noted that the group containing an oxyalkylene group is a group having an oxyalkylene structure, and the oxyalkylene structure is also called an alkylene oxide structure.

[0069] In the case where a part of the hydrogen atoms that the hydrocarbon group of R can have is replaced by a substituent, the number of substituents is preferably less than 50% of the number of hydrogen atoms of the hydrocarbon group when R has no substituent, and more preferably less than 10%. In addition, the number of substituents is preferably less than 5, and particularly preferably less than 3. It is further preferably less than 2, and more preferably less than 1. In addition, the number of substituents is 0 or more, and the lower limit of the number of substituents when substituted by a substituent is 1 or more. From the perspective of having a tendency to have better dispersion stability, the substituent is preferably provided on the carbon atom that is located at the farthest position from the phosphorus atom in the formula.

[0070] In the inkjet ink composition according to the present embodiment, the compound represented by the general formula (1) and the compound represented by the general formula (2) preferably have R in the formula a hydrocarbon group having 10 or more carbon atoms. It is more preferred that R in the formula be a hydrocarbon group having 12 to 30 carbon atoms. Furthermore, the number of carbon atoms of the hydrocarbon group of R in the formula is more preferably 12 to 25, more preferably 12 to 23, more preferably 14 to 22, particularly preferably 15 to 20, and even more particularly preferably 17 to 20. When the number of carbon atoms of the hydrocarbon group of R in the formula is particularly 15 to 20, preferably within the above range, there is a tendency for the dispersion stability (water resistance) and metallic gloss to be more excellent.

[0071] It should be noted that R in the above general formula (1) and the above general formula (2) is preferably a hydrocarbon group having the same number of carbon atoms, and more preferably a hydrocarbon group having the same R. With such R, it is presumed that the specific alkyl phosphate is uniformly attached to the surface of the metal particles, and there is a tendency to achieve a good balance between water resistance and glossiness.

[0072] In addition, R in the above general formula (1) and the above general formula (2) is any one of an alkyl group, an alkenyl group, and an alkynyl group, and more preferably a carbon skeleton having 10 or more carbon atoms. In this case, a carbon skeleton having 10 or more carbon atoms and 30 or less carbon atoms is preferred. Furthermore, the carbon skeleton preferably has 10 or more carbon atoms and 25 or less, more preferably 12 or more carbon atoms and 23 or less, further preferably 14 or more carbon atoms and 21 or less, and particularly preferably 16 or more carbon atoms and 19 or less. R is any one of an alkyl group, an alkenyl group, and an alkynyl group, and when the carbon number is within the above range, there is a tendency for the dispersion stability and metallic gloss to be more excellent.

[0073] Specific examples of the compound (monomer) represented by the general formula (1) include monooctyl phosphate, monolauryl phosphate, monoisotridecyl phosphate, and monostearyl phosphate, preferably at least one selected from these, more preferably at least one selected from monoisotridecyl phosphate and monostearyl phosphate, and still more preferably monostearyl phosphate.

[0074] Specific examples of the compound (dimer) represented by the general formula (2) include dioctyl phosphate, dilauryl phosphate, diisotridecyl phosphate, and distearyl phosphate, preferably at least one selected from these, more preferably at least one selected from diisotridecyl phosphate and distearyl phosphate, and still more preferably distearyl phosphate.

[0075] It should be noted that the inkjet ink composition involved in the present embodiment may also contain a surface treatment agent other than the above-mentioned specific alkyl phosphate as long as it does not damage the effect of the present invention. As such a surface treatment agent, for example, a fluorine compound can be listed. As a fluorine compound, a compound containing fluorine and one or more selected from phosphorus, sulfur, and nitrogen as a constituent element can be preferably used, specifically, a fluorine phosphonic acid, a fluorine carboxylic acid, a fluorine sulfonic acid, and their salts can be listed.

[0076] The surface treatment of the metal particles with the surface treatment agent can be performed, for example, when a metal film formed by a vapor phase film formation method is pulverized in a liquid to form metal particles as described above, by preliminarily adding the surface treatment agent to the liquid.

[0077] 1.1.2.2 Content

[0078] In the inkjet ink composition according to this embodiment, the mass ratio of the compound represented by the general formula (2) to the total of the compound represented by the general formula (1) and the compound represented by the general formula (2) is 45 mass % or less.

[0079] By containing the compound represented by the general formula (1) (monomer) and the compound represented by the general formula (2) (dimer) having different properties as the surface treatment agent in a predetermined content ratio, a balance between water resistance and gloss can be achieved, making both excellent.

[0080] The upper limit of the mass ratio of the compound represented by the general formula (2) relative to the total of the compound represented by the general formula (1) and the compound represented by the general formula (2) is preferably 42% by mass or less, more preferably 39% by mass or less, further preferably 36% by mass or less, further preferably 33% by mass or less, particularly preferably 30% by mass or less, and more particularly preferably 27% by mass or less. Further, it is preferably 23% by mass or less, more preferably 20% by mass or less, further preferably 17% by mass or less, further preferably 14% by mass or less, and particularly preferably 11% by mass or less. In addition, the lower limit of the mass ratio of the compound represented by the general formula (2) relative to the total of the compound represented by the general formula (1) and the compound represented by the general formula (2) is not particularly limited, and is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, further preferably 1% by mass or more, further preferably 2% by mass or more, particularly preferably 3% by mass or more, and more particularly preferably 4% by mass or more. Furthermore, it is preferably 5% by mass or more, more preferably 6% by mass or more, further preferably 7% by mass or more, further preferably 8% by mass or more, and particularly preferably 9% by mass or more. On the other hand, the lower limit of the above mass ratio is preferably 10% by mass or more, more preferably 15% by mass or more, further preferably 20% by mass or more, further preferably 25% by mass or more, particularly preferably 30% by mass or more, and particularly preferably 35% by mass or more.

[0081] The content of the compound represented by the general formula (2) is preferably 1 to 20% by mass, more preferably 3 to 18% by mass, further preferably 5 to 16% by mass, particularly preferably 7 to 14% by mass, and even more preferably 8 to 12% by mass, relative to the total of the compound represented by the general formula (1) and the compound represented by the general formula (2).

[0082] When the mass ratio of the compound represented by the general formula (2) to the total of the compound represented by the general formula (1) and the compound represented by the general formula (2) is within the above range, water resistance and gloss are easily balanced, and both tend to be more excellent.

[0083] It should be noted that the above-mentioned mass ratio of the compound represented by the general formula (1) and the compound represented by the general formula (2) contained in the surface treatment agent can also be said to be the mass ratio of the compound represented by the general formula (1) and the compound represented by the general formula (2) bonded to the surface of the metal particles in the metal pigment contained in the ink composition. It should be noted that the following contents of the compound represented by the general formula (1) and the compound represented by the general formula (2) relative to the ink composition are also the same, and the contents can also be said to be the amounts of the compound represented by the general formula (1) and the compound represented by the general formula (2) bonded to the surface of the metal particles in the metal pigment contained in the ink composition.

[0084] The lower limit of the content of the compound represented by the general formula (1) is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, further preferably 0.010% by mass or more, further preferably 0.030% by mass or more, and particularly preferably 0.050% by mass or more, relative to the total mass of the inkjet ink composition. Further, it is preferably 0.070% by mass or more, and more preferably 0.080% by mass or more. On the other hand, the lower limit of the content of the compound represented by the general formula (1) is preferably 0.090% by mass or more, more preferably 0.100% by mass or more, further preferably 0.110% by mass or more, further preferably 0.120% by mass or more, and particularly preferably 0.130% by mass or more, relative to the total mass of the inkjet ink composition.

[0085] The upper limit of the content of the compound represented by the general formula (1) is not particularly limited, but is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, further preferably 2.0% by mass or less, further preferably 1.5% by mass or less, and particularly preferably 1.0% by mass or less, relative to the total mass of the inkjet ink composition. Further, it is preferably 0.800% by mass or less, more preferably 0.600% by mass or less, further preferably 0.400% by mass or less, particularly preferably 0.200% by mass or less, and further preferably 0.150% by mass or less. It is particularly preferably 0.120% by mass or less, more preferably 0.100% by mass or less, and further preferably 0.095% by mass or less. On the other hand, the upper limit of the content of the compound represented by the general formula (1) is preferably 0.080 mass % or less, more preferably 0.060 mass % or less, further preferably 0.040 mass % or less, particularly preferably 0.020 mass % or less, and even more preferably 0.010 mass % or less, relative to the total mass of the inkjet ink composition.

[0086] When the content of the compound represented by the general formula (1) is within the above range, the dispersion stability and gloss of the metallic pigment tend to be more excellent.

[0087] The lower limit of the content of the compound represented by the general formula (2) is preferably 0.0001% by mass or more, more preferably 0.0005% by mass or more, further preferably 0.0010% by mass or more, further preferably 0.0100% by mass or more, particularly preferably 0.0200% by mass or more, further preferably 0.0300% by mass or more, more preferably 0.0400% by mass or more, further preferably 0.0500% by mass or more, particularly preferably 0.0550% by mass or more, relative to the total mass of the inkjet ink composition.

[0088] The upper limit of the content of the compound represented by the general formula (2) is not particularly limited, but is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, further preferably 2.0% by mass or less, further preferably 1.5% by mass or less, and particularly preferably 1.0% by mass or less, relative to the total mass of the inkjet ink composition. Further, it is preferably 0.800% by mass or less, more preferably 0.600% by mass or less, further preferably 0.400% by mass or less, particularly preferably 0.200% by mass or less, and further preferably 0.150% by mass or less. In particular, it is preferably 0.100% by mass or less, more preferably 0.090% by mass or less, further preferably 0.080% by mass or less, particularly preferably 0.070% by mass or less, and further preferably 0.060% by mass or less. On the other hand, the upper limit of the content of the compound represented by the general formula (2) is preferably 0.050 mass % or less, more preferably 0.040 mass % or less, further preferably 0.030 mass % or less, further preferably 0.020 mass % or less, and particularly preferably 0.010 mass % or less, relative to the total mass of the inkjet ink composition. Further, it is preferably 0.009 mass % or less, more preferably 0.007 mass % or less, further preferably 0.005 mass % or less, further preferably 0.003 mass % or less, and particularly preferably 0.002 mass % or less.

[0089] When the content of the compound represented by the general formula (2) is within the above range, water resistance tends to be further improved.

[0090] The content of the surface treatment agent is preferably 1 to 100 mass %, more preferably 1 to 70 mass %, further preferably 1 to 50 mass %, further preferably 2 to 40 mass %, particularly preferably 4 to 30 mass %, more particularly preferably 6 to 20 mass %, and particularly preferably 8 to 15 mass %, relative to 100 mass % of the total mass of the metal particles. It should be noted that the content of the surface treatment agent is preferably the total content of the compound represented by the general formula (1) and the compound represented by the general formula (2).

[0091] When the content of the surface treatment agent is within the above range relative to 100% by mass of the total mass of the metal particles, there is a tendency to improve the ejection stability of the ink composition, the dispersion stability of the metal particles, the water resistance, and the glossiness of the colored body produced using the ink composition. In addition, the ejection stability during long-term storage or storage under harsh conditions may be improved.

[0092] The content of the compound represented by the general formula (1) is preferably 0.5 to 90 mass %, more preferably 0.5 to 70 mass %, further preferably 1 to 50 mass %, further preferably 2 to 30 mass %, particularly preferably 3 to 20 mass %, and even more preferably 4 to 15 mass %, relative to 100 mass % of the total mass of the metal particles.

[0093] When the content of the compound represented by the general formula (1) is within the above range relative to 100% by mass of the total mass of the metal particles, the dispersion stability and gloss of the metallic pigment tend to be more excellent.

[0094] The content of the compound represented by general formula (2) is preferably 0.05 to 30 mass %, more preferably 0.1 to 25 mass %, further preferably 1 to 20 mass %, further preferably 2 to 15 mass %, and particularly preferably 3 to 10 mass %, relative to 100 mass % of the total mass of the metal particles.

[0095] When the content of the compound represented by the general formula (2) is within the above range relative to 100% by mass of the total mass of the metal particles, water resistance tends to be further improved.

[0096] 1.1.3 Volume average particle size and average thickness of metallic pigments

[0097] The inkjet ink composition according to the present embodiment preferably has a volume average particle size (D50) of the metallic pigment of 0.5 μm or less and an average thickness of the metallic pigment of 30 nm or less.

[0098] The lower limit of the volume average particle size (D50) of the metallic pigment is not particularly limited, but is preferably 0.10 μm or more, more preferably 0.20 μm or more, further preferably 0.25 μm, and particularly preferably 0.30 μm. In addition, the upper limit of the volume average particle size (D50) of the metallic pigment is not particularly limited, but may be 5.00 μm or less, 3.00 μm or less, 1.00 μm or less, 0.70 μm or less, 0.55 μm or less, preferably 0.45 μm or less, more preferably 0.40 μm or less, further preferably 0.35 μm or less, particularly preferably 0.30 μm or less, and even more preferably 0.25 μm or less.

[0099] It should be noted that in the present invention, the volume average particle size (D50) refers to the median particle size of the volume distribution obtained by measuring the metal pigment dispersion using the laser diffraction scattering method, and is the size of the particle whose cumulative value is exactly 50% of the median value when a plurality of measurement results are expressed as the accumulation of the existence ratio of each size. It should be noted that in the case where the metal particles are scaly, the volume average particle size is obtained based on the shape and size of the metal particles when converted to a spherical shape.

[0100] The lower limit of the average thickness of the metallic pigment is not particularly limited, but is preferably 5 nm or more, more preferably 7 nm or more, further preferably 9 nm or more, particularly preferably 11 nm or more, and more particularly preferably 13 nm or more. In addition, the upper limit of the average thickness of the metallic pigment is not particularly limited, but may be 60 nm or less, or 40 nm or less, preferably 25 nm or less, more preferably 23 nm or less, further preferably 21 nm or less, particularly preferably 19 nm or less, and more particularly preferably 17 nm or less.

[0101] It should be noted that the average thickness of the metal pigment can be measured using an atomic force microscope (AFM). For example, it can be measured by using an atomic force microscope method using NanoNavi E-Sweep (manufactured by SIINANOTECHNOLOGY), but is not limited thereto. For example, 50 random metal pigments are used for measurement and the average value is taken. That is, the average thickness is preferably the arithmetic mean thickness.

[0102] When the volume average particle size (D50) and the average thickness of the metallic pigment are within the above ranges, the storage stability and water resistance of the ink composition can be improved, and unintentional color unevenness can be more effectively prevented from occurring in the colored body produced using the ink composition, and the gloss and abrasion resistance of the colored body can tend to be improved.

[0103] 1.2 Organic solvents

[0104] The inkjet ink composition involved in this embodiment contains an organic solvent. Examples of the organic solvent include esters, alkylene glycol ethers, cyclic esters, nitrogen-containing solvents, alcohols, polyols, etc. Examples of the nitrogen-containing solvent include cyclic amides, non-cyclic amides, etc. Examples of the non-cyclic amides include alkoxyalkyl amides, etc.

[0105] Examples of the esters include ethylene glycol monoacetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, and methoxybutyl acetate; and glycol diesters such as ethylene glycol diacetate, diethylene glycol diacetate, propylene glycol diacetate, dipropylene glycol diacetate, ethylene glycol propionate acetate, ethylene glycol butyl acetate, diethylene glycol butyl acetate, diethylene glycol propionate acetate, diethylene glycol butyl acetate, propylene glycol propionate acetate, propylene glycol butyl acetate, dipropylene glycol butyl acetate, and dipropylene glycol propionate acetate.

[0106] As the alkylene glycol ethers, any alkylene glycol monoether or diether may be used, and alkyl ethers are preferred. Specific examples thereof include alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, and tripropylene glycol monobutyl ether. and alkylene glycol dialkyl ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl butyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, triethylene glycol methyl butyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether and tripropylene glycol dimethyl ether.

[0107] It should be noted that, among the alkylene glycols described above, diethers tend to dissolve or swell the resin in the ink composition more easily than monoethers, and are preferred from the viewpoint of further improving the friction fastness.

[0108] Examples of the cyclic esters include cyclic esters (lactones) such as β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, β-butyrolactone, β-valerolactone, γ-valerolactone, β-caprolactone, γ-caprolactone, δ-caprolactone, β-heptanolactone, γ-heptanolactone, δ-heptanolactone, ε-heptanolactone, γ-octanolactone, δ-octanolactone, ε-octanolactone, δ-nonanolactone, ε-nonanolactone, and ε-decanolactone, and compounds wherein the hydrogen atoms of the methylene groups adjacent to the carbonyl groups are substituted by alkyl groups having 1 to 4 carbon atoms.

[0109] Examples of the alkoxyalkylamides include 3-methoxy-N,N-dimethylpropionamide, 3-methoxy-N,N-diethylpropionamide, 3-methoxy-N,N-methylethylpropionamide, 3-ethoxy-N,N-dimethylpropionamide, 3-ethoxy-N,N-diethylpropionamide, 3-ethoxy-N,N-methylethylpropionamide, 3-n-butoxy-N,N-dimethylpropionamide, 3-n-butoxy-N,N-diethylpropionamide, 3-n-butoxy-N,N-methyl Ethyl propionamide, 3-n-propoxy-N,N-dimethyl propionamide, 3-n-propoxy-N,N-diethyl propionamide, 3-n-propoxy-N,N-methylethyl propionamide, 3-isopropoxy-N,N-dimethyl propionamide, 3-isopropoxy-N,N-diethyl propionamide, 3-isopropoxy-N,N-methylethyl propionamide, 3-tert-butoxy-N,N-dimethyl propionamide, 3-tert-butoxy-N,N-diethyl propionamide, 3-tert-butoxy-N,N-methylethyl propionamide, etc.

[0110] As cyclic amides, lactams can be listed, for example, pyrrolidones such as 2-pyrrolidone, 1-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, 1-propyl-2-pyrrolidone, 1-butyl-2-pyrrolidone, etc. can be listed. From the viewpoint of promoting the film coating of the resin, these are preferred, and 2-pyrrolidone is particularly more preferred.

[0111] As alcohols, for example, compounds in which one hydrogen atom of an alkane is replaced by a hydroxyl group can be cited. As the alkane, an alkane having a carbon number of 10 or less is preferred, an alkane having a carbon number of 6 or less is more preferred, and an alkane having a carbon number of 3 or less is further preferred. The number of carbon atoms of the alkane is 1 or more, preferably 2 or more. The alkane may be a straight chain type or a branched chain type. As alcohols, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, tert-butanol, isobutanol, n-pentanol, 2-pentanol, 3-pentanol, and tert-pentanol can be cited.

[0112] Polyols have two or more hydroxyl groups in the molecule. Polyols can be divided into, for example, alkanediols and polyols.

[0113] The so-called alkanediols include, for example, compounds in which an alkane is substituted with two hydroxyl groups. Examples of the alkanediols include ethylene glycol (also known as ethane-1,2-diol), propylene glycol (also known as propane-1,2-diol), 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-octanediol, 1,3-propanediol, 1,3-butanediol (also known as 1,3-butanediol), 1,4-butanediol, 2,3-butanediol, 1,2-pentanediol, 1,5-pentanediol, 2.4-pentanediol, 2-methyl-1,3-propanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,3-pentanediol, 3-methyl-1,5-pentanediol, 2-methylpentane-2,4-diol, 1,6-hexanediol, 2-ethyl-2-methyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, etc.

[0114] Examples of the polyols include condensates of two or more molecules of alkanediols intermolecularly condensed at hydroxyl groups, and compounds having three or more hydroxyl groups.

[0115] Examples of the condensate formed by intermolecular condensation of two or more molecules of an alkanediol at hydroxyl groups include dialkylene glycols such as diethylene glycol and dipropylene glycol, and trialkylene glycols such as triethylene glycol and tripropylene glycol.

[0116] The compound having three or more hydroxyl groups is a compound having three or more hydroxyl groups with an alkane and / or polyether structure as a skeleton. Examples of the compound having three or more hydroxyl groups include glycerol, trimethylolethane, trimethylolpropane, 1,2,5-hexanetriol, 1,2,6-hexanetriol, pentaerythritol, and polyoxypropylenetriol.

[0117] The above organic solvents may be used alone or in combination of two or more.

[0118] The organic solvent preferably contains at least one selected from alkylene glycol ethers and cyclic esters, and more preferably contains at least one selected from diethylene glycol diethyl ether, tetraethylene glycol monobutyl ether and γ-butyrolactone.

[0119] The content of the organic solvent is preferably 30% by mass or more, more preferably 40% by mass or more, further preferably 50% by mass or more, further preferably 60% by mass or more, and particularly preferably 70% by mass or more, relative to the total mass of the inkjet ink composition. The upper limit is less than 100% by mass. In addition, the lower limit of the content of the organic solvent relative to the total mass of the inkjet ink composition is also preferably within the above range, and the upper limit is also preferably 99% by mass or less, and further preferably 98% by mass or less.

[0120] 1.3 Polyoxyalkyleneamine compounds

[0121] The inkjet ink composition according to the present embodiment preferably contains a polyoxyalkyleneamine compound. By containing a polyoxyalkyleneamine compound, the storage stability of the inkjet ink composition can be improved, and there is a tendency that the ejection stability of the inkjet ink composition when the inkjet ink composition is stored for a long time or stored under harsh conditions and the glossiness of the produced recorded material can be improved.

[0122] The polyoxyalkyleneamine compound may be any compound as long as it is an amine compound having a polyoxyalkylene structure in the molecule, but is preferably at least one of a compound represented by the following formula (3) and a salt thereof, and a compound represented by the following formula (4) and a salt thereof.

[0123] [Chemical formula 1]

[0124]

[0125] (In formula (3), R is a hydrogen atom or an alkyl group having 3 or less carbon atoms, and x is an integer of 10 or more. In formula (3), multiple oxyalkylene units having different conditions for R may be present.)

[0126] [Chemical formula 2]

[0127]

[0128] (In formula (4), R1, R2, and R3 are each independently an alkyl group having 3 or less carbon atoms, and n is an integer of 10 or more.)

[0129] This can improve the storage stability of the inkjet ink composition, and tends to improve the discharge stability of the inkjet ink composition when the inkjet ink composition is stored for a long time or under severe conditions and the glossiness of the produced recorded matter.

[0130] R in the above formula (3) may be a hydrogen atom or an alkyl group having 3 or less carbon atoms, preferably a hydrogen atom or a methyl group, and more preferably a compound represented by the following formula (5).

[0131] [Chemical formula 3]

[0132]

[0133] (In formula (5), X1 and X2 are independently an integer greater than 1, and X1+X2 is an integer greater than 10. In formula (5), the order of the ethylene oxide unit and the propylene oxide unit is not limited.)

[0134] This can make the storage stability of the inkjet ink composition particularly excellent, and there is a tendency that the ejection stability of the inkjet ink composition when the inkjet ink composition is stored for a long period of time or under severe conditions and the glossiness of the produced recorded matter can be particularly excellent.

[0135] In addition, the ratio of X1 to X2 in the above formula (5), i.e., the value of X1 / X2, i.e., the ratio of the amount of ethylene oxide units to the amount of propylene oxide units in the molecule of the polyoxyalkyleneamine compound, is preferably 0.05, more preferably 0.15, and even more preferably 0.70. In addition, the upper limit of the value of X1 / X2 is preferably 10.00, more preferably 8.00, and even more preferably 6.00.

[0136] Examples of commercially available polyoxyalkyleneamine compounds that satisfy such conditions include JEFFAMIN M2070 (manufactured by Huntsman) and GENAMIN (M41 / 2000) (manufactured by Clariant).

[0137] As described above, the order of the ethylene oxide unit and the propylene oxide unit in the above formula (5) is not limited. More specifically, in the above formula (5), an amino group is bonded to the terminal of the continuous ethylene oxide unit, and a methyl group is bonded to the terminal of the continuous propylene oxide unit, but an amino group may be bonded to the terminal of the continuous propylene oxide unit, and a methyl group may be bonded to the terminal of the continuous ethylene oxide unit. In addition, the compound represented by the above formula (5) may be a block copolymer or a random copolymer.

[0138] In the above formula (4), R1, R2, and R3 are each independently an alkyl group having 3 or less carbon atoms, preferably a methyl group or an ethyl group. In particular, it is more preferred that one of R1, R2, and R3 is a methyl group and the other two are ethyl groups.

[0139] A compound in which one of R1, R2, and R3 in the above formula (4) is a methyl group and the other two are ethyl groups is represented by the following formula (6).

[0140] [Chemical formula 4]

[0141]

[0142] (In formula (6), n is an integer greater than or equal to 10.)

[0143] In addition, although not shown in the above formula (4) and the above formula (6), these compounds have anions corresponding to the cations shown in these formulas. Examples of such anions include halide ions such as chloride ions and bromide ions, hydroxide ions, sulfate ions, nitrate ions, and phosphate ions.

[0144] The lower limit of the weight average molecular weight of the polyoxyalkyleneamine compound is not particularly limited, but is preferably 300, more preferably 500, further 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 further preferably 3000.

[0145] The polyoxyalkyleneamine compounds may be used alone or in combination of two or more.

[0146] When a polyoxyalkyleneamine compound is contained, the lower limit of the content of the polyoxyalkyleneamine compound in the inkjet ink composition is not particularly limited, but is preferably 0.01% by mass or more, more preferably 0.06% by mass or more, and even more preferably 0.10% by mass or more. In addition, the upper limit of the content of the polyoxyalkyleneamine compound in the inkjet ink composition is not particularly limited, but is preferably 3.0% by mass or less, more preferably 1.0% by mass or less, even more preferably 0.5% by mass or less, and particularly preferably 0.3% by mass or less.

[0147] In addition, the content of the polyoxyalkyleneamine compound is preferably 0.1 to 30% by mass relative to the total mass 100% by mass of the metal particles. The lower limit of the content of the polyoxyalkyleneamine compound relative to the total mass 100% by mass of the metal particles is more preferably 0.5% by mass or more, further preferably 1% by mass or more, further preferably 3% by mass or more, particularly preferably 5% by mass or more, and more particularly preferably 7% by mass or more. The upper limit of the content of the polyoxyalkyleneamine compound relative to the total mass 100% by mass of the metal particles is more preferably 25% by mass or less, further preferably 20% by mass or less, particularly preferably 17% by mass or less, more particularly preferably 14% by mass or less, and particularly preferably 12% by mass or less.

[0148] When the content of the polyoxyalkyleneamine compound is within the above range relative to 100% by mass of the total mass of the metal particles, the storage stability of the inkjet ink composition can be further improved, and when the inkjet ink composition is stored for a long period of time or under severe conditions, the ejection stability of the inkjet ink composition and the glossiness of the produced recorded matter tend to be further improved.

[0149] 1.4 Resin

[0150] The inkjet ink composition involved in the present embodiment preferably contains a resin. The resin acts as a binder. As the resin, for example, acrylic resin, rosin-modified resin, terpene resin, polyester resin, polyamide resin, epoxy resin, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer, cellulose resin (such as cellulose acetate butyrate, hydroxypropyl cellulose), polyvinyl butyral, polypropylene polyol, polyvinyl alcohol, polyurethane resin, etc. can be listed. Among them, it is preferred to contain one or more selected from acrylic resin, polyester resin, polyurethane resin, and cellulose resin, and more preferably contain acrylic resin. It should be noted that acrylic resin is a resin obtained by polymerizing at least acrylic monomer, and can also be a copolymer resin of acrylic monomer and other monomers. Other monomers can be listed, for example, vinyl monomers, etc.

[0151] The lower limit of the content of the resin is preferably 0.01% by mass or more, more preferably 0.06% by mass or more, further preferably 0.10% by mass or more, and particularly preferably 0.15% by mass or more, relative to the total mass of the inkjet ink composition. The upper limit of the content of the resin is preferably 3.0% by mass or less, more preferably 1.0% by mass or less, further preferably 0.5% by mass or less, and particularly preferably 0.3% by mass or less, relative to the total mass of the inkjet ink composition.

[0152] 1.5 Other ingredients

[0153] The inkjet ink composition according to the present embodiment may contain ingredients other than those mentioned above. Examples of such ingredients include leveling agents, polymerization accelerators, polymerization inhibitors, photopolymerization initiators, dispersants, surfactants, penetration enhancers, humectants, colorants, fixers, mildewproofing agents, preservatives, antioxidants, chelating agents, thickeners, sensitizers, and the like.

[0154] Preferred examples of the surfactant include silicone-based surfactants and acetylene glycol-based surfactants.

[0155] 2. Recording Method

[0156] A recording method according to one embodiment of the present invention comprises a step of ejecting the inkjet ink composition by an inkjet method to allow the inkjet ink composition to adhere to a recording medium.

[0157] According to the recording method involved in this embodiment, a diester and a monoester of a specific alkyl phosphate are used as a surface treatment agent for a metallic pigment. Since the above-mentioned inkjet ink composition having a content ratio of these diesters and monoesters within a predetermined range is used, excellent water resistance (humidity resistance) can be obtained, and the glossiness can be made to be continuous and storage stability can be excellent.

[0158] 2.1 Ink Adhesion Process

[0159] The recording method according to the present embodiment includes a step of ejecting the above-mentioned inkjet ink composition by an inkjet method to make it adhere to a recording medium (ink adhesion step).

[0160] The inkjet method refers to a recording method in which droplets of ink or the like are ejected from the nozzle of an inkjet head of an inkjet recording device or the like and applied to a recording medium. When the ink composition is ejected by the inkjet method, as the inkjet method, a piezoelectric method or a method in which the ink is ejected by heating the ink to generate bubbles can be used, but from the viewpoint of the difficulty of deterioration of the metallic pigment, the piezoelectric method is preferred.

[0161] The ink composition can be discharged by the inkjet method using a known liquid droplet discharge device.

[0162] The colored portion formed by the ink composition may have, for example, a predetermined pattern, or may be formed on the entire surface of the object to be processed.

[0163] The amount of inkjet ink composition deposited per unit area of ​​the recording area is preferably 1 to 10 mg / inch. 2 , more preferably 2 to 7 mg / inch 2 .

[0164] Recording medium

[0165] The recording medium is an object to be colored by causing the inkjet ink composition to adhere thereto, that is, an object to be colored.

[0166] Examples of recording media include ink-absorbing recording media such as paper and cloth. This is a recording medium whose recording surface easily absorbs ink. Examples of paper include ordinary paper, special paper for inkjet, corrugated paper, etc. Examples of cloth include natural fibers such as cotton, polyester, and wool, synthetic fibers, and nonwoven fabrics.

[0167] In addition, non-absorbent recording media made of plastic materials, metals, glass, ceramics, wood, etc. can be cited. This is a recording medium whose recording surface is difficult to absorb ink. As recording media made of plastic materials, plastic films, plastic plates, etc. can be cited. As plastics, for example, vinyl chloride, polyester, polyolefin, etc. can be cited, but not limited to these. As polyester, polyethylene terephthalate, etc. can be cited.

[0168] In addition, low-absorbency recording media can also be cited. This is a recording medium whose absorbency of the recording surface is inferior to that of a non-absorbent recording medium and has low absorbency. As a low-absorbency recording medium, a recording medium having a coating layer (receiving layer) for receiving a liquid on the surface can be cited, for example, as a recording medium whose substrate is paper, printing paper can be cited. The coating layer is difficult to absorb ink, and a coating layer coated with particles such as inorganic compounds and an adhesive can be cited.

[0169] The low-absorption or non-absorption recording medium is a recording medium that does not absorb liquid at all or hardly absorbs liquid. For example, the non-absorption or low-absorption recording medium preferably has a "bearing temperature of 30 msec from the start of contact in the Bristow method". 1 / 2 The water absorption is 10mL / m 2 The Bristow method is the most popular method for measuring the amount of liquid absorbed in a short period of time, and is also adopted by the Japan Pulp and Paper Technology Association (JAPANTAPPI). Details of the test method are described in Standard No. 51 "Paper and Board - Liquid Absorption Test Method - Bristow Method" of "JAPANTAPPI Pulp Test Method 2000 Edition". In contrast, absorbent recording media refers to recording media that do not belong to non-absorbent and low-absorbent recording media.

[0170] The shape of the recording medium is not particularly limited, and may be any shape such as a sheet, a plate, or an object.

[0171] 2.2 Primary heating process

[0172] The recording method according to the present embodiment may include a primary heating step which is a step of early heating the ink composition attached to the recording medium.

[0173] The primary heating process is a process for heating and drying the ink attached to the recording medium at an early stage. The primary heating process is a heating process for drying at least a part of the liquid medium of the ink attached to the recording medium to at least a degree that reduces the flow of the ink.

[0174] The ink may be attached to the heated recording medium in the first heating step, or the heating may be performed at an early stage after the ink is attached. It is preferred that the ink droplets landed on the recording medium be heated within 0.5 seconds at the latest after the ink droplets landed.

[0175] In addition, the heating step is preferably performed once for each attached ink composition. For example, when the ink attaching step is performed using two or more inkjet ink compositions, it is preferably performed once for each attached ink composition.

[0176] The primary heating step is preferably performed by irradiating with an IR heater, irradiating with microwaves, using a platen heater, or sending hot air to the recording medium using a fan.

[0177] The heating in the primary heating step can be performed at least in any one of the periods before, at the same time as, or in the early period after the ink attachment step, preferably at the same time. The ink attachment step can be performed in such a heating sequence. It is particularly preferred to heat the recording medium and attach the ink composition to the heated recording medium in the ink attachment step.

[0178] In the case of a single heating step, since the ink composition can be quickly dried on the recording medium, the ink can be prevented from bleeding, which is preferred. On the other hand, in the case of a single heating step, since the ink is quickly dried, the floating time of the metal pigment may not be sufficiently ensured, and the gloss may be poor, or the ejection stability may be poor due to the heat of the single heating step. However, according to the recording method involved in this embodiment, by using the above-mentioned inkjet ink composition, excellent gloss and ejection stability can be obtained even when a single heating step is performed, which is preferred.

[0179] The surface temperature of the recording surface of the recording medium in the first heating process for heating the ink composition is preferably 30°C or more. On the other hand, it is preferably 60°C or less. It is further preferably 35°C or more and 55°C or less, and further preferably 40°C or more and 50°C or less. If the surface temperature of the recording medium is as described above, the prevention of bleeding and the ejection stability are better, so it is preferred. It should be noted that the surface temperature of the recording medium in the first heating process is the surface temperature of the recording medium when the ink is attached, or the temperature of the recording medium when heated when heating is performed after attachment. It is also the highest temperature during recording.

[0180] 2.3 Post-heating process

[0181] The recording method according to the present embodiment may include a post-heating step (secondary heating step) of heating the recording medium after the ink adhesion step.

[0182] The post-heating step is a heating step for completing the recording and heating the recorded material sufficiently to allow it to be used. The post-heating step is a heating step for fully drying the solvent component of the ink.

[0183] The post-heating step is preferably started more than 0.5 seconds after the ink adheres to the recording medium. For example, it is preferred to start heating a certain recording area of ​​the recording medium more than 0.5 seconds after the ink has completely adhered to the area.

[0184] The heating of the recording medium in the post-heating step can be performed, for example, using an appropriate heating mechanism. The surface temperature of the recording medium at this time is preferably 50° C. or higher, more preferably 60° C. or higher, 70° C. or higher, or 75° C. or higher. The upper limit is not limited, but is preferably 120° C. or lower. In addition, the heating temperature is preferably below the softening point of the substrate of the recording medium.

[0185] 2.4 Recording Device

[0186] Hereinafter, an example of a recording device that can be applied to the recording method according to the present embodiment will be described with reference to the drawings.

[0187] Outline of the device structure

[0188] Figure 1 FIG. 2 is a schematic cross-sectional view schematically showing a recording device. Figure 1 As shown, the inkjet recording device 1 includes a recording head 2, an IR heater 3, a platen 4, a heater 5, a cooling fan 6, a preheater 7, and a ventilation fan 8. In addition, the recording head is mounted on a carriage not shown in the figure, and performs a main scan in the direction of the back side to the front side of the figure to attach the ink to the recording medium M. In addition, a platen heater not shown in the figure is provided on the platen 4. The inkjet recording device 1 includes a control unit not shown in the figure, which controls each part to perform recording. In addition, the recording head 2 receives the supply of ink from the ink container not shown in the figure.

[0189] Structure of inkjet head

[0190] The recording head 2 as an inkjet head is configured to perform recording on the recording medium M by ejecting an ink composition from a nozzle of the recording head 2 and causing the ink composition to adhere. Figure 1 The recording head 2 shown is a serial recording head, which performs multiple scans in the main scanning direction relative to the recording medium M to make the ink adhere to the recording medium M. The recording head 2 is mounted on a carriage not shown in the figure. The recording head 2 performs multiple scans in the main scanning direction relative to the recording medium M by the operation of a carriage moving mechanism that moves the carriage in the medium width direction (the inner side to the near front side direction in the figure) of the recording medium M. The medium width direction refers to the main scanning direction of the recording head 2. Scanning in the main scanning direction is also called main scanning.

[0191] Here, the main scanning direction is the direction in which the carriage carrying the recording head 2 moves. Figure 1 The direction is the sub-scanning direction intersecting the conveying direction of the recording medium M indicated by the arrow SS. Then, the recording medium M is recorded by repeating the main scanning of the recording head 2 and the sub-scanning as the conveying of the recording medium M for a plurality of times.

[0192] The recording head 2 can use a conventionally known method for ejecting liquid droplets, for example, a method of ejecting liquid droplets using the vibration of a piezoelectric element, that is, an ejection method of forming ink droplets by mechanical deformation of an electrostrictive element.

[0193] Primary heating mechanism

[0194] The inkjet recording device 1 can be equipped with a primary heating mechanism, which performs a primary heating process for heating the recording medium M when the ink is ejected from the recording head 2 and attached to the recording medium. The primary heating mechanism can use a conductive type, an air supply type, a radiation type, etc. The conductive type is to conduct heat from a component in contact with the recording medium to the recording medium. For example, a platen heater can be listed. It should be noted that, although not shown in the figure, the platen heater is integrally provided with the platen 4. The air supply type is to send normal temperature air or hot air to the recording medium to dry the ink. For example, an air supply fan can be listed. The radiation type is to radiate radiation that generates heat to the recording medium to heat the recording medium. For example, IR radiation can be listed. In addition, although not shown in the figure, a heater similar to the platen heater can be set on the downstream side of the platen 4 closer to the SS direction. These primary heating mechanisms can be used alone or in combination.

[0195] For example, the primary heating mechanism includes an IR heater 3 and a platen heater.

[0196] It should be noted that when the IR heater 3 is used, the recording medium M can be heated radially by infrared radiation from the recording head 2 side. As a result, the recording head 2 is also easily heated at the same time, but compared with the case of heating the back side of the recording medium M such as a platen heater, the temperature can be increased without being affected by the thickness of the recording medium M. It should be noted that the primary heating mechanism can also be equipped with various fans (such as a ventilation fan 8), which blow hot air or air at the same temperature as the environment onto the recording medium M to dry the ink on the recording medium M.

[0197] The platen heater can heat the recording medium M via the platen 4 at a position facing the recording head 2. The platen heater can heat the recording medium M in a conductive manner, and is used as necessary in the inkjet recording method.

[0198] Furthermore, the inkjet recording apparatus 1 may include a preheater 7 for preheating the recording medium M before the ink is attached to the recording medium M.

[0199] After heating mechanism

[0200] A post-heating mechanism may be provided for performing a post-heating step of heating the recording medium after the ink attaching step to dry and fix the ink.

[0201] The heater 5 used in the post-heating mechanism dries and solidifies the ink attached to the recording medium M. By heating the recording medium M with the image recorded thereon by the heater 5, the organic solvent contained in the ink can be evaporated and dispersed more quickly. In this way, a recorded object can be obtained in a shorter time.

[0202] Other structures

[0203] The inkjet recording apparatus 1 may include a cooling fan 6. After the ink recorded on the recording medium M is dried, the ink on the recording medium M is cooled by the cooling fan 6, so that an ink coating film can be formed on the recording medium M with good adhesion.

[0204] Figure 1 The recording device shown is a serial printer that performs recording in a so-called serial method. The recording device may also be a line printer that has a line head and performs recording in a line method.

[0205] The line head has a nozzle array having a plurality of nozzles arranged in the width direction of the recording medium, and has a length greater than the width of the recording medium M being transported, and can record an image in the width direction of the recording medium M being transported. In addition, recording can be performed by a single scan. Alternatively, after a scanning is performed by transporting the recording medium once, the recording medium can be returned to the opposite direction of the transport direction and transported again to perform scanning again, thereby performing recording by performing two or more scans.

[0206] It should be noted that the scanning may be performed by a nozzle whose position is fixed relative to the recording medium being transported, or the nozzle may be scanned while moving relative to the recording medium fixed in the platen area.

[0207] It should be noted that the recording device capable of line recording can be used in addition to changing the recording head 2 to a line head. Figure 1 Specifically, the Figure 1 The ventilation fan 8, IR heater 3, platen heater, preheater 7 and other heating mechanisms above the recording head 2 shown in the figure may be similarly arranged above or below the line head. Figure 1 The post-heating mechanism shown is a heater 5 and a cooling fan 6, etc.

[0208] 3. Example

[0209] Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples. % below refers to mass basis unless otherwise specified.

[0210] 3.1 Preparation of inkjet ink composition

[0211] Diethylene glycol diethyl ether, tetraethylene glycol monobutyl ether, γ-butyrolactone and a resin were added to a metal pigment dispersion prepared by the following method to obtain the compositions shown in Tables 1 and 2 below, thereby obtaining inkjet ink compositions according to Examples and Comparative Examples.

[0212] Method for producing metallic pigment dispersion

[0213] First, a polyethylene terephthalate film with a smooth surface having a surface roughness Ra of 0.02 μm or less was prepared. Then, a release resin soluble in acetone was applied to the entire surface of one surface of the film using a roll coater to form a release layer. The polyethylene terephthalate film formed with the release layer was transported to a vacuum evaporation device at a speed of 5 m / s to form a film of 15 nm or 60 nm in thickness composed of Al under reduced pressure. Next, the polyethylene terephthalate film formed with the Al film was immersed in tetrahydrofuran and ultrasonic vibration of 40 kHz was applied to obtain a dispersion of a metal powder as an aggregate of metal particles made of Al.

[0214] The tetrahydrofuran was removed by a centrifugal separator, and diethylene glycol diethyl ether was added to obtain a suspension having a metal powder content of 5% by mass. Next, the suspension was treated with a circulating high-power ultrasonic pulverizer to pulverize the metal particles to a predetermined size as described in each embodiment and each comparative example in Tables 1 and 2 below. During this treatment, 20 kHz ultrasonic waves were applied.

[0215] Next, when a polyoxyalkyleneamine compound is used, it is added to the suspension, and heat-treated at 55°C for 1 hour under 40 kHz ultrasonic irradiation to release the aggregation of the metal particles and disperse the metal particles in the form of primary particles. Here, as the polyoxyalkyleneamine compound, a block copolymer in which an amino group is bonded to the terminal of a continuous ethylene oxide unit and a methyl group is bonded to the terminal of a continuous propylene oxide unit is used, and a polyoxyalkyleneamine compound having a weight average molecular weight of 2000 and satisfying the condition of X1 / X2 being 3.1 between X1 and X2 in the above formula (5) is used.

[0216] Furthermore, a hydrophobic phosphoric acid-based surface treatment agent such as alkyl phosphate, alkylphosphonic acid or fluorine-containing phosphonic acid was added thereto as a surface treatment agent, and then a heat treatment was performed at 55° C. for 3 hours under 28 kHz ultrasonic irradiation to obtain a metallic pigment dispersion.

[0217]

[0218]

[0219] Supplementary explanation is given about the records in Tables 1 and 2 above.

[0220] pigment

[0221] "D50" in the table represents the volume average particle size (D50), which was measured using Microtrac MT-3300 (Microtrac Bel, laser diffraction scattering particle size distribution measuring device). In addition, "film thickness" is the average thickness, which is measured by using the atomic force microscopy method of NanoNavi E-Sweep (SIINANOTECHNOLOGY), measured with 50 arbitrary metal pigments and averaged. It should be noted that the volume average particle size (D50) and the average thickness are measured for the pigments that have been surface treated.

[0222] Surface treatment agent

[0223] Alkyl phosphate

[0224] In the table, "R carbon number" represents the carbon number of the hydrocarbon group R in the following general formula (1) or the following general formula (2).

[0225] (RO-)P(O)(OH)2……(1)

[0226] (RO-)2P(O)(OH)……(2)

[0227] (In the formula, R is independently a hydrocarbon group having 8 or more carbon atoms.)

[0228] · Monobutyl phosphate: A compound that does not belong to the specified alkyl phosphates, "JAMP-4" manufactured by Johoku Chemical Co., Ltd.

[0229] Monooctyl phosphate: the compound represented by the above general formula (1) (the number of carbon atoms of R in the formula is 8), "JAMP-8EH" manufactured by Johoku Chemical Co., Ltd.

[0230] Monolauryl phosphate: the compound represented by the general formula (1) (the number of carbon atoms of R in the formula is 12), "JAMP-12" manufactured by Johoku Chemical Co., Ltd.

[0231] Monoisotridecyl phosphate: The compound represented by the general formula (1) (in which R has 13 carbon atoms) was used after being isolated from "Phoslex A-13" manufactured by SC Organic Chemicals Co., Ltd., which was a mixed product of a monomer and a dimer.

[0232] Monostearyl phosphate: The compound represented by the general formula (1) (in which R has 18 carbon atoms) was isolated from "Phoslex A-18" manufactured by SC Organic Chemicals Co., Ltd., which is a mixture of a monomer and a dimer, and used.

[0233] Dibutyl phosphate: A compound that does not belong to the specified alkyl phosphates, manufactured by Tokyo Chemical Industry Co., Ltd. (Product code: P0260)

[0234] Dioctyl phosphate: the compound represented by the general formula (2) (the carbon number of R in the formula is 8), manufactured by Tokyo Chemical Industry Co., Ltd. (product code: P0811)

[0235] Dilauryl phosphate: the compound represented by the above general formula (2) (the carbon number of R in the formula is 12), "JP-212" manufactured by Johoku Chemical Co., Ltd.

[0236] Diisotridecyl phosphate: The compound represented by the general formula (2) (in which R has 13 carbon atoms) was used after being isolated from "Phoslex A-13" manufactured by SC Organic Chemicals Co., Ltd., which was a mixed product of a monomer and a dimer.

[0237] Distearyl phosphate: The compound represented by the general formula (2) (in which R has 18 carbon atoms) was isolated from "Phoslex A-18" manufactured by SC Organic Chemicals Co., Ltd., which is a mixture of a monomer and a dimer, and used.

[0238] Alkylphosphonic acid

[0239] · Dodecylphosphonic acid: a compound not belonging to the specified alkyl phosphate, manufactured by Tokyo Chemical Industry Co., Ltd. (product code: D4809)

[0240] Fluorinated phosphonic acid

[0241] · FHP: 2-(Perfluorohexyl)ethylphosphonic acid, a compound not belonging to the specified alkyl phosphate, manufactured by UNIMATEC

[0242] Poly(EO / EO)amine

[0243] JEFFAMINM2070: polyoxyalkyleneamine compound, CAS 83713-01-3, manufactured by Huntsman, between X1 and X2 in the above formula (5), X1 / X2 is 3.1, and the weight average molecular weight is 2000

[0244] Resin

[0245] UC3000: Made by Toagosei Co., Ltd., acrylic resin

[0246] Solvents

[0247] ·DEDG: Diethylene glycol diethyl ether

[0248] BTGH: Tetraethylene glycol monobutyl ether

[0249] γBL: γ-butyrolactone

[0250] In the table, "dimer / (dimer+monomer)" means phosphoric acid diester / (phosphoric acid diester+phosphoric acid monoester).

[0251] It should be noted that, regarding the inkjet ink composition of each example, the metal pigment was separated from the dispersion of the metal pigment after the surface treatment and the residual dispersion medium was analyzed, and the result showed that the surface treatment agent was not contained. Therefore, the "dimer / dimer+monomer" in each example in the table can also be said to be the mass ratio of the surface treatment agent attached to the metal particles contained in the ink composition.

[0252] 3.2 Evaluation methods

[0253] 3.2.1 Gloss (initial)

[0254] The inkjet ink compositions of the examples and comparative examples obtained above were applied to a polyvinyl chloride film (Mactac 5829R) using a bar coater (#7). The film was then dried on a hot plate at 60°C for 10 minutes to obtain a recorded object. The glossiness of the recorded portion of the obtained recorded object was measured at a shaking angle of 20° using a gloss meter (MINOLTA MULTIGLOSS 268) and evaluated according to the following criteria. It can be said that the larger the value, the better the metallic glossiness.

[0255] Evaluation Benchmarks

[0256] AA: Glossiness is above 650

[0257] A: Glossiness is 600 or more and less than 650

[0258] B: Glossiness is 500 or more and less than 600

[0259] C: Glossiness is 400 or more and less than 500

[0260] D: Glossiness is 300 or more and less than 400

[0261] E: Glossiness less than 300

[0262] 3.2.2 Storage stability in an open atmosphere system

[0263] The inkjet ink compositions of each embodiment and each comparative example obtained above were stored in an ink bag and placed in a constant temperature bath at 50°C for 7 days. At this time, it was assumed that there was a trace amount of water as an impurity and water that had penetrated during long-term storage, and the test was conducted so that each ink contained 0.1% by mass of water. Then, the volume average particle size (D50) of the metallic pigment was measured using a particle size distribution meter (made by Microtrac, MT3300EXII), and the increase in particle size compared to the initial stage was compared and evaluated according to the following criteria. It should be noted that it can be said that the smaller the increase rate of the volume average particle size (D50), the better the water resistance of the metallic pigment.

[0264] Evaluation Benchmarks

[0265] A: Particle size increase within 3%

[0266] B: Particle size increased from 3% to less than 5%

[0267] C: Particle size increased from 5% to less than 10%

[0268] D: Particle size increased by 10% or more

[0269] 3.2.3 Abrasion resistance under high temperature and high humidity

[0270] In the same manner as in the above-mentioned "gloss (initial) test", the recorded materials involved in each embodiment and each comparative example were obtained. After being placed in a thermostatic chamber (temperature 40°C, humidity 100%) for 24 hours, the abrasion resistance was evaluated using a Gakushin type friction fastness tester (manufactured by Tester Industry Co., Ltd., trade name "AB-301") in accordance with JIS K5701 (ISO 11628). That is, a cotton cloth was placed on the recording surface of the recorded material, and rubbed back and forth 20 times with a load of 500 g. For the gloss value of the recording surface of the rubbed recorded material, the gloss at a shaking angle of 20° was measured using a gloss meter (MINOLTA MULTIGLOSS 268). The evaluation criteria are as follows. It is the reduction rate of gloss compared to the benchmark when the gloss measured before being placed in the thermostatic chamber is taken as the benchmark (100%).

[0271] Evaluation Benchmarks

[0272] A: Gloss reduction is less than 5%

[0273] B: Gloss reduction is less than 10%

[0274] C: Gloss reduction is less than 20%

[0275] D: Gloss reduction of more than 20%

[0276] 3.2.4 Ejection stability

[0277] An inkjet printer (modified SC-S80650, manufactured by Seiko Epson) was prepared. Figure 1 The droplet ejection device was set in a chamber (heat treatment chamber). The inkjet ink compositions involved in the above-obtained embodiments and comparative examples were prepared, and droplets of each ink composition were continuously ejected from each nozzle of the inkjet head (recording head 2) under an environment of 25°C and 50%RH while optimizing the driving waveform of the piezoelectric element. The droplets were observed at a position 0.8 mm from the nozzle in the ejection direction.

[0278] Regarding the flying images of the droplets 40 seconds after the start of ejection, the images where the ink droplets were not ejected or were significantly bent at a distance of more than 25% from the adjacent nozzles were counted and summarized as the number of defective nozzles, and evaluated according to the following criteria. It should be noted that the number of defective nozzles is the ratio (%) to the total number of nozzles.

[0279] Evaluation Benchmarks

[0280] AA: The number of defective nozzles is less than 3%

[0281] A: The number of defective nozzles is 3% or more and less than 5%

[0282] B: The number of defective nozzles is 5% or more and less than 10%

[0283] C: The number of defective nozzles is 10% or more and less than 20%

[0284] D: The number of defective nozzles is more than 20%

[0285] 3.3 Evaluation results

[0286] The evaluation results are shown in Tables 1 and 2 above.

[0287] As can be seen from Tables 1 and 2 above, the inkjet ink compositions involved in each example are excellent in water resistance and metallic gloss. The inkjet ink compositions involved in each example are solvent-based inks containing a metal pigment and an organic solvent. The metal pigment is a metal particle whose surface is treated with a surface treatment agent. The surface treatment agent contains the compound represented by the general formula (1) and the compound represented by the general formula (2). The mass ratio of the compound represented by the general formula (2) to the total of the compound represented by the general formula (1) and the compound represented by the general formula (2) is 45% by mass or less.

[0288] From the comparison between Example 1 and Comparative Example 1, it is found that when the specific alkyl phosphate in which R has 8 or more carbon atoms, both glossiness and water resistance are excellent.

[0289] From the comparison between Example 7 and Comparative Examples 2 to 8, it can be seen that when a specific alkyl phosphate is contained and the monomer and the dimer are within a predetermined mass ratio, both the glossiness and the water resistance are excellent.

[0290] The results of Examples 1 to 3 and 17 show that the larger the volume average particle size D50 of the pigment, the better the glossiness, but the more likely the ejection stability is to deteriorate. In addition, the results of Examples 8 and 18 show that the thinner the pigment film thickness, the better the glossiness.

[0291] From the results of Examples 1, 4, 6, 7, and 16, it is understood that each of the specific alkyl phosphates is excellent in both gloss and water resistance.

[0292] From the results of Examples 7 to 9 and 15, it is understood that the mass ratio of the monomer to the dimer in the specific alkyl phosphate ester is within a wide range and both the glossiness and water resistance are excellent.

[0293] From the results of Examples 1 and 14, it is understood that when a polyoxyalkyleneamine compound is contained, there is a tendency for discharge stability to become good.

[0294] From the results of Examples 9 to 11, it is understood that when the polyoxyalkyleneamine compound is contained in a predetermined content, the glossiness and discharge stability tend to be improved.

[0295] From the results of Examples 9 and 12 to 13, it is understood that when the content of the specific alkyl phosphate is within a wide range, both the glossiness and the water resistance are excellent.

[0296] In addition, it is understood that in Example 13, the effect of a large content of the specific alkyl phosphate is high in the liquid medium.

[0297] The following contents can be derived from the above-mentioned embodiments.

[0298] One embodiment of the inkjet ink composition, wherein

[0299] The inkjet ink composition is a solvent-based ink containing a metal pigment and an organic solvent.

[0300] The metallic pigment is a metal particle whose surface is treated with a surface treatment agent.

[0301] The surface treatment agent contains a compound represented by the general formula (1) and a compound represented by the general formula (2), wherein the mass ratio of the compound represented by the general formula (2) to the total of the compound represented by the general formula (1) and the compound represented by the general formula (2) is 45 mass % or less.

[0302] (RO-)P(O)(OH)2......(1)

[0303] (RO-)2P(O)(OH)......(2)

[0304] (In the formula, R is independently a hydrocarbon group having 8 or more carbon atoms.)

[0305] In one embodiment of the inkjet ink composition,

[0306] The content of the compound represented by the general formula (2) is 1 to 20% by mass based on the total amount of the compound represented by the general formula (1) and the compound represented by the general formula (2).

[0307] Alternatively, in any aspect of the above-mentioned inkjet ink composition,

[0308] The compound represented by the general formula (1) and the compound represented by the general formula (2) are compounds wherein R is a hydrocarbon group having 15 to 20 carbon atoms.

[0309] Alternatively, in any aspect of the above-mentioned inkjet ink composition,

[0310] The metal particles are made of aluminum or an aluminum alloy.

[0311] Alternatively, in any aspect of the above-mentioned inkjet ink composition,

[0312] The content of the surface treatment agent is 1 to 50% by mass relative to 100% by mass of the total mass of the metal particles.

[0313] Alternatively, in any aspect of the above-mentioned inkjet ink composition,

[0314] The metal particles are in the shape of scales.

[0315] Alternatively, in any aspect of the above-mentioned inkjet ink composition,

[0316] The volume average particle size (D50) of the metallic pigment is 0.5 μm or less, and the average thickness of the metallic pigment is 30 nm or less.

[0317] Alternatively, in any aspect of the above-mentioned inkjet ink composition,

[0318] Contains polyoxyalkyleneamine compounds.

[0319] In an embodiment of the inkjet ink composition containing the polyoxyalkyleneamine compound,

[0320] The content of the polyoxyalkyleneamine compound is 0.1 to 30% by mass relative to 100% by mass of the total mass of the metal particles.

[0321] A way of recording a method, where

[0322] The method comprises the step of ejecting the inkjet ink composition of any one of the above-mentioned aspects by an inkjet method to make it adhere to a recording medium.

[0323] The present invention is not limited to the above-mentioned embodiments, and various modifications are possible. For example, the present invention includes a structure that is substantially the same as the structure described in the embodiments, such as a structure with the same function, method and result, or a structure with the same purpose and effect. In addition, the present invention includes a structure that replaces a non-essential part of the structure described in the embodiments. In addition, the present invention includes a structure that has the same effect as the structure described in the embodiments, or a structure that can achieve the same purpose. In addition, the present invention includes a structure in which a known technology is added to the structure described in the embodiments.

Claims

1. An inkjet ink composition, characterized in that The inkjet ink composition is a solvent-based ink containing a metal pigment and an organic solvent. The metallic pigment is a metal particle whose surface is treated with a surface treatment agent. The surface treatment agent contains a compound represented by the general formula (1) and a compound represented by the general formula (2), wherein the mass ratio of the compound represented by the general formula (2) to the total of the compound represented by the general formula (1) and the compound represented by the general formula (2) is 45 mass % or less, (RO-)P(O)(OH)2……(1) (RO-)2P(O)(OH)……(2) In the formula, R is independently a hydrocarbon group having 8 or more carbon atoms.

2. The inkjet ink composition according to claim 1, characterized in that The content of the compound represented by the general formula (2) is 1% by mass to 20% by mass based on the total of the compound represented by the general formula (1) and the compound represented by the general formula (2).

3. The inkjet ink composition according to claim 1 or 2, characterized in that The compound represented by the general formula (1) and the compound represented by the general formula (2) are compounds wherein R is a hydrocarbon group having 15 to 20 carbon atoms.

4. The inkjet ink composition according to claim 1, characterized in that The metal particles are made of aluminum or an aluminum alloy.

5. The inkjet ink composition according to claim 1, characterized in that The content of the surface treatment agent is 1% by mass to 50% by mass relative to 100% by mass of the total mass of the metal particles.

6. The inkjet ink composition according to claim 1, characterized in that The metal particles are in the shape of scales.

7. The inkjet ink composition according to claim 1, characterized in that The volume average particle size D50 of the metal pigment is less than 0.5 μm, and the average thickness of the metal pigment is less than 30 nm.

8. The inkjet ink composition according to claim 1, characterized in that Contains polyoxyalkyleneamine compounds.

9. The inkjet ink composition according to claim 8, characterized in that The content of the polyoxyalkyleneamine compound is 0.1% by mass to 30% by mass based on 100% by mass of the total mass of the metal particles.

10. A recording method, characterized in that: The method comprises the step of ejecting the inkjet ink composition according to any one of claims 1 to 9 by an inkjet method to allow the inkjet ink composition to adhere to a recording medium.

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