Non-aqueous inkjet ink composition

Abstract

To obtain an ink composition having excellent gloss and scratch resistance.SOLUTION: There is provided a non-aqueous inkjet ink composition comprising a brilliant pigment, a polyoxyalkylene amine compound, a binder resin and a liquid medium component, wherein the brilliant pigment is composed of metal particles, the brilliant pigment is surface-modified with a surface treatment agent, the surface treatment agent is one or more selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2), the binder resin has a weight average molecular weight of 30000 or less and an acid value of 50 mgKOH / g or less and is an acrylic resin and the content of the binder resin is 0.1 mass% or more and 2.0 mass% or less based on the total amount of the ink composition. Formula (1): (A-R1-O)aP(O)(OH)3-a, Formula (2): (E-R2)bP(O)(OH)3-bSELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a non-aqueous ink-jet ink composition. [Background technology]

[0002] Inkjet recording methods are capable of recording high-resolution images and have been rapidly developing in various fields. Among these methods, recording methods using ink compositions containing glitter pigments are widely used because they can impart a luxurious gloss to a variety of recording media. Patent Document 1 describes one such composition, a metallic pigment composition containing a specific metallic pigment, a polyoxyalkyleneamine compound, and a liquid medium component. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-117052 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with conventional technology, the particle size of the bright pigment is about 1 μm, and it tends to settle more easily than other pigments, which makes ink ejection unstable and limits the printing drive frequency. Therefore, efforts have been made to reduce the size of the pigment and print at high frequencies, but it has been difficult to achieve both stable printing at high frequencies and high gloss.

[0005] Furthermore, when printing on a variety of recording media, the ink composition of Patent Document 1 contains a small amount of cellulose acetate butyrate (CAB) as the binder resin, and therefore does not provide good abrasion resistance for some recording media. [Means for solving the problem]

[0006] The present invention provides a non-aqueous inkjet ink composition comprising a bright pigment, a polyoxyalkyleneamine compound, a binder resin, and a liquid medium component, wherein the bright pigment comprises metal particles whose surfaces have been modified with a surface treatment agent, and the surface treatment agent is at least one selected from the group consisting of compounds represented by the following formula (1) and compounds represented by the following formula (2), the binder resin is an acrylic resin having a weight-average molecular weight of 30,000 or less and an acid value of 50 mgKOH / g or less, and the content of the binder resin is 0.1% by mass or more and 2.0% by mass or less, relative to the total amount of the ink composition. (AR 1 -O) a P(O)(OH) 3-a (1) (In formula (1), A is a hydrogen atom, a carboxyl group, a hydroxyl group, an amino group, or an oxyalkylene-containing group; R 1 is a divalent hydrocarbon group having 10 or more carbon atoms, and a is 1 or 2. (ER 2 ) b P(O)(OH) 3-b (2) (In formula (2), E is a hydrogen atom, a carboxyl group, a hydroxyl group, an amino group, or an oxyalkylene-containing group; R 2 is a divalent hydrocarbon group having 10 or more carbon atoms, and b is 1 or 2. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a flowchart illustrating an example of an inkjet recording method. [Figure 2] Table 1 shows the compositions of non-aqueous inkjet ink compositions. [Figure 3] Table 2 shows the compositions of non-aqueous inkjet ink compositions. [Figure 4] Table 3 shows the compositions of non-aqueous inkjet ink compositions. [Figure 5] Table 4 shows the compositions of non-aqueous inkjet ink compositions. [Figure 6] Table 5 shows the evaluation results. [Figure 7] Table 6 shows the evaluation results. [Figure 8] Table 7 shows the evaluation results. [Figure 9] Table 8 shows the evaluation results. DETAILED DESCRIPTION OF THE INVENTION

[0008] Below, we will explain in detail the embodiment of the present invention (hereinafter referred to as the ``present embodiment''), but the present invention is not limited to this and various modifications are possible within the scope of the gist of the present invention.

[0009] 1. Non-aqueous inkjet ink composition The non-aqueous inkjet ink composition (hereinafter also referred to as "ink composition") of this embodiment comprises a glittering pigment, a polyoxyalkyleneamine compound, a binder resin, and a liquid medium component, wherein the glittering pigment is composed of metal particles whose surfaces have been modified with a surface treatment agent, and the surface treatment agent is at least one selected from the group consisting of compounds represented by the following formula (1) and compounds represented by the following formula (2), the binder resin is an acrylic resin having a weight-average molecular weight of 30,000 or less and an acid value of 50 mgKOH / g or less, and the content of the binder resin is 0.1% by mass or more and 2.0% by mass or less, based on the total amount of the ink composition. (AR 1 -O) a P(O)(OH) 3-a (1) (In formula (1), A is a hydrogen atom, a carboxyl group, a hydroxyl group, an amino group, or an oxyalkylene-containing group; R 1 is a divalent hydrocarbon group having 10 or more carbon atoms, and a is 1 or 2. (ER 2 ) b P(O)(OH) 3-b (2) (In formula (2), E is a hydrogen atom, a carboxyl group, a hydroxyl group, an amino group, or an oxyalkylene-containing group; R 2is a divalent hydrocarbon group having 10 or more carbon atoms, and b is 1 or 2.

[0010] According to this embodiment, an ink composition having excellent gloss and abrasion resistance can be obtained.

[0011] Although the reason why such excellent effects are obtained by this embodiment is not clear, the inventors presume as follows.

[0012] Conventional non-aqueous ink compositions impart abrasion resistance to a recording medium by swelling the recording medium with a solvent contained in the composition and fusing the solvent with a binder resin. To impart excellent abrasion resistance, a large amount of binder resin must be blended. However, as the blending amount increases, the viscosity of the ink composition increases when dried, reducing the fluidity of the glitter pigment and disrupting the orientation of the pigment on the recording medium. This makes the ink more susceptible to yellowing and loss of gloss.

[0013] Furthermore, to obtain excellent ink ejection performance, it is necessary to make the luster pigment finer, but the smaller the size of the luster pigment, the greater the disturbance in orientation due to increased viscosity. Therefore, to make the luster pigment finer, it is necessary to reduce the amount of resin blended in to suppress the increase in viscosity, but as mentioned above, this makes it difficult to obtain abrasion resistance to the recording medium.

[0014] On the other hand, the non-aqueous inkjet ink composition of this embodiment contains a bright pigment that is metal particles that have been surface-treated with a specific phosphoric acid-based surface treatment agent, a polyoxyalkyleneamine compound, and a liquid medium component, as well as a specific amount of an acrylic resin as a binder resin, the acrylic resin having a weight-average molecular weight of 30,000 or less and an acid value of 50 mgKOH / g or less.

[0015] The acrylic resin has a relatively low molecular weight, with a weight-average molecular weight of 30,000 or less, and a low acid value of 50 mgKOH / g or less. Using such an acrylic resin as a binder resin stabilizes the dispersibility of the glitter pigment, thereby suppressing an increase in the viscosity of the ink composition even when the glitter pigment is present at a high concentration. This allows the amount of acrylic resin to be increased for the same viscosity, resulting in an ink composition with excellent abrasion resistance. Additionally, the ink composition can fully express the gloss of the glitter pigment while providing abrasion resistance to a variety of recording media, regardless of the type of recording medium. Furthermore, the glitter pigment can be finely divided to achieve excellent ink ejection performance. Furthermore, the acrylic resin has little effect on the gloss of the glitter pigment, thereby enabling the gloss of the glitter pigment to be fully expressed. The low acid value of the acrylic resin prevents the glitter pigment from aggregating, thereby maintaining the performance of the highly dispersible glitter pigment ink over a long period of time.

[0016] Furthermore, the polyoxyalkyleneamine compound contained in the ink composition can suppress aggregation of the bright pigment through steric interactions. Furthermore, because the bright pigment is surface-treated with a specific phosphoric acid compound, changing the surface condition of the pigment can cause the bright pigment to align at the gas-liquid interface during drying, thereby enhancing gloss, or can increase the affinity between the bright pigments after drying, thereby improving adhesion. Because the ink composition contains a well-balanced mixture of acidic and basic components, the ink composition can ensure fluidity even when viscosity increases during drying, controlling the orientation of the pigment on the recording medium and reducing yellowing and gloss loss. Furthermore, because the ink composition can ensure fluidity, excellent ink ejection properties can be achieved, enabling high-frequency printing.

[0017] From the above, it is presumed that the ink composition of this embodiment can provide an ink composition with excellent gloss and abrasion resistance, although the reason is not limited to this.

[0018] Next, each component contained in the ink composition will be described.

[0019] 1.1. Photoluminescent pigments The ink composition of this embodiment contains a glittering pigment. The glittering pigment is made of metal particles whose surfaces have been modified with a surface treatment agent. The surface treatment agent is one or more compounds selected from the group consisting of compounds represented by the following formula (1) and compounds represented by the following formula (2). The glittering pigment may be used alone or in combination of two or more types.

[0020] Equation (1): (AR 1 -O) a P(O)(OH) 3-a (In formula (1), A is a hydrogen atom, a carboxyl group, a hydroxyl group, an amino group, or an oxyalkylene-containing group; R 1 is a divalent hydrocarbon group having 10 or more carbon atoms, and a is 1 or 2.

[0021] Equation (2): (ER 2 ) b P(O)(OH) 3-b (In formula (2), E is a hydrogen atom, a carboxyl group, a hydroxyl group, an amino group, or an oxyalkylene-containing group; R 2 is a divalent hydrocarbon group having 10 or more carbon atoms, and b is 1 or 2.

[0022] 1.1.1. Metal particles Metal particles are components that have a significant effect on the appearance of bright pigments, with at least a portion of the visible portion being made of a metal material, and typically the portion near the outer surface being made of a metal material.

[0023] The metal particles may be any particles at least in the region including the surface area, which is made of a metal material. Such metal particles may be, for example, entirely made of a metal material, or may have a base made of a non-metallic material and a coating made of a metal material that covers the base. The metal particles may have an oxide coating, such as a passivation film, formed on their surfaces.

[0024] The metal material constituting the metal particles can be a simple metal or various alloys, etc. Examples of such metal materials include aluminum (hereinafter also referred to as "Al"), silver, gold, platinum, nickel, chromium, tin, zinc, indium, titanium, iron, and copper.

[0025] The metal particles are preferably Al or an aluminum alloy (hereinafter also referred to as "Al alloy"). Because Al is an amphoteric metal, the interaction between the basic component of the polyoxyalkyleneamine compound contained in the ink composition and the acidic component of the specific phosphoric acid compound, which is a surface treatment agent, can ensure the fluidity of the ink composition even if an increase in viscosity occurs during drying. As a result, the orientation of the pigment on the recording medium can be more controlled, making it less likely that yellowing or loss of gloss will occur. Furthermore, since the fluidity of the ink composition can be more assured, better ink ejection properties can be obtained, and high-frequency printing can be more easily performed. Furthermore, the use of Al or an Al alloy tends to result in an ink composition with better gloss and a luxurious feel.

[0026] Examples of the shape of the metal particles include spherical, spindle-shaped, scaly, and needle-shaped. The shape of the metal particles is preferably scaly. When the shape of the metal particles is scaly, an ink composition having better gloss and abrasion resistance, and also better gloss storage stability and ejection stability tends to be obtained.

[0027] The average thickness of the metal particles is preferably 5 nm or more and 90 nm or less, more preferably 10 nm or more and 70 nm or less. When the average thickness of the metal particles is within the above range, an ink composition having superior gloss and abrasion resistance, and also superior gloss storage stability and ejection stability, tends to be obtained. In this specification, the average thickness of the metal particles can be calculated as the average value by measuring 50 random metal particles using an atomic force microscope, for example.

[0028] The volume-average particle diameter of the metal particles is preferably 0.20 μm or more and 1.00 μm or less, more preferably 0.25 μm or more and 0.90 μm or less, and even more preferably 0.30 μm or more and 0.80 μm or less. When the average particle diameter of the metal particles is within the above range, the ink composition tends to have better gloss and abrasion resistance, and also better gloss storage stability and ejection stability. In this specification, the volume-average particle diameter refers to the median diameter of the volume distribution measured using a laser diffraction / scattering method for a particle dispersion. When the results of multiple measurements are expressed as the cumulative abundance ratio of each size, the volume-average particle diameter is the particle size that represents 50% of the cumulative median. When the metal particles are scaly, the volume-average particle diameter is determined based on the shape and size of the metal particles when converted to spherical particles.

[0029] The content of the metal particles is preferably 0.1% by mass or more and 2.4% by mass or less, more preferably 0.2% by mass or more and 2.2% by mass or less, and even more preferably 0.3% by mass or more and 1.8% by mass or less, relative to the total amount of the ink composition. When the content of the metal particles is within the above range, the ink composition tends to have better gloss and abrasion resistance, and also better gloss storage stability and ejection stability.

[0030] 1.1.2.Surface treatment agents The surface treatment agent is one or more selected from the group consisting of compounds represented by the above formula (1) and compounds represented by the above formula (2). The surface treatment agent may be used alone or in combination of two or more. With regard to the surface treatment of the bright pigment, it is presumed that the hydroxy groups on the surface of the metal particles react with the phosphorus-containing acid groups of the surface treatment agent, thereby bonding the metal particles and the surface treatment agent through covalent bonds, hydrogen bonds, or the like, to form the bright pigment.

[0031] A in the above formula (1) and E in the above formula (2) are preferably hydrogen atoms. When A or E is a hydrogen atom, an ink composition having superior gloss and abrasion resistance, as well as superior gloss storage stability and ejection stability tends to be obtained.

[0032] R in the above formula (1) 1 and R in the above formula (2) 2 is preferably a divalent hydrocarbon group having from 10 to 30 carbon atoms, more preferably from 12 to 28 carbon atoms, even more preferably from 13 to 25 carbon atoms, still more preferably from 14 to 25 carbon atoms, and even more preferably from 15 to 25. When the number of carbon atoms is within the above range, an ink composition having better gloss and abrasion resistance, and also better gloss storage stability and ejection stability tends to be obtained.

[0033] Examples of the divalent hydrocarbon group include an alkylene group, an alkenylene group, and an alkynylene group.

[0034] In the ink composition, the surface treatment agent is preferably a mixture containing multiple types of compounds. In such a case, the bright pigment may be the same metal particles that have been surface-treated with multiple types of surface treatment agents. The ink composition may contain bright pigments that have been surface-treated with different surface treatment agents.

[0035] The surface treatment of the metal pigment with a surface treatment agent can be carried out, for example, by adding the surface treatment agent to the liquid when a metal film formed by a vapor deposition method is pulverized in the liquid to form metal particles. Specifically, the surface treatment can be carried out by applying ultrasonic vibrations to a liquid containing the metal particles and the surface treatment agent, followed by heat treatment. Note that the liquid may be one exemplified in the method for producing a bright pigment described below. For specific surface treatment methods, see the examples.

[0036] When the same metal particles are surface-treated with multiple types of surface treatment agents, the surface treatment may be performed in multiple steps corresponding to the respective surface treatment agents, or the surface treatment may be performed with the multiple types of surface treatment agents in the same step.

[0037] The surface treatment with the surface treatment agent may be carried out by adding the surface treatment agent to a liquid containing the metal pigment and / or the luster pigment.

[0038] Alternatively, the surface treatment with a surface treatment agent may be carried out by preparing a liquid containing metal particles and a polyoxyalkyleneamine compound described below and adding the surface treatment agent to the liquid. That is, the bright pigment may be obtained by surface-modifying metal particles surface-modified with a polyoxyalkyleneamine compound with one or more surface treatment agents selected from the group consisting of compounds represented by formula (1) and compounds represented by formula (2). In this case, it is presumed that part or all of the polyoxyalkyleneamine compound is bonded to the surface of the metal particles through a reaction between hydroxyl groups and amino groups on the surface of the metal particles.

[0039] The content of the surface treatment agent is preferably 0.01% by mass or more and 1.2% by mass or less, more preferably 0.03% by mass or more and 1.1% by mass or less, and even more preferably 0.05% by mass or more and 0.9% by mass or less, relative to the total amount of the ink composition. When the content of the surface treatment agent is within the above range, an ink composition having better gloss and abrasion resistance, and also better gloss storage stability and ejection stability tends to be obtained.

[0040] The content of the surface treatment agent is preferably 1.0 part by mass or more and 50 parts by mass or less, more preferably 1.5 parts by mass or more and 40 parts by mass or less, and even more preferably 2.0 parts by mass or more and 30 parts by mass or less, relative to 100 parts by mass of the metal particles. When the content of the surface treatment agent is within the above range, an ink composition having better gloss and abrasion resistance, and further having better gloss storage stability and ejection stability tends to be obtained.

[0041] 1.1.3. Content of lustrous pigment The content of the luster pigment is preferably 0.11% by mass or more and 3.6% by mass or less, more preferably 0.23% by mass or more and 3.3% by mass or less, and even more preferably 0.35% by mass or more and 2.7% by mass or less, relative to the total amount of the ink composition. When the content of the luster pigment is within the above range, the ink composition tends to have better gloss and abrasion resistance, and also better gloss storage stability and ejection stability.

[0042] 1.1.4. Manufacturing method of luster pigments The bright pigment can be produced by a known method, and is not particularly limited.

[0043] When the metal in the bright pigment is, for example, Al or an Al alloy, the metal particles can be obtained by forming a film composed of Al or an Al alloy by a vapor deposition method and then pulverizing the film. When producing metal particles using such a method, the metal particles can be suitably produced, for example, by forming a film composed of Al or an Al alloy on a substrate. Examples of the substrate include plastic films such as polyethylene terephthalate. The substrate may have a release agent layer on the film-forming surface.

[0044] The pulverization may be performed by applying ultrasonic vibrations to the film in a liquid. This allows metal particles to be obtained easily and reliably, and also reduces variations in size, shape, and properties among the individual metal particles. For specific pulverization methods, please refer to the Examples.

[0045] Examples of liquids include alcohols; hydrocarbon compounds; ether compounds; and polar compounds such as propylene carbonate, γ-butyrolactone, N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, cyclohexanone, and acetonitrile.

[0046] Alcohols include, for example, methanol, ethanol, propanol, and butanol.

[0047] Examples of hydrocarbon compounds include n-heptane, n-octane, decane, dodecane, tetradecane, toluene, xylene, cymene, durene, indene, dipentene, tetrahydronaphthalene, decahydronaphthalene, and cyclohexylbenzene.

[0048] 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.

[0049] 1.2. Polyoxyalkyleneamine compounds The ink composition of this embodiment contains a polyoxyalkyleneamine compound. The polyoxyalkyleneamine compound is an amine compound having a polyoxyalkylene structure in the molecule. The polyoxyalkyleneamine compound may be used alone or in combination of two or more types.

[0050] The polyoxyalkyleneamine compound is preferably a compound represented by the following formula (3) or a salt thereof. By using the compound represented by the following formula (3) or a salt thereof, an ink composition having better gloss and abrasion resistance, as well as better gloss storage stability and ejection stability, tends to be obtained.

[0051] R 3 -(OR 4 ) x -NH2(3) In formula (3), R 3 is a hydrogen atom or an alkyl group having 4 or less carbon atoms. 4 is an alkylene group having 5 or less carbon atoms. x is an integer of 5 or more. A polyoxyalkyleneamine compound has, in its molecule, R 4 may contain a plurality of different alkylene groups.

[0052] In formula (3), R 3 is preferably an alkyl group having 4 or less carbon atoms, more preferably an alkyl group having 1 or 2 carbon atoms. 4 is preferably an alkylene group having a carbon number of 1 to 3. The alkylene group may be linear or branched.

[0053] The compound represented by formula (3) or a salt thereof is preferably a compound represented by the following formula (4) or a salt thereof: By using the compound represented by formula (4) or a salt thereof, an ink composition having even more excellent gloss and abrasion resistance, as well as even more excellent gloss storage stability and ejection stability tends to be obtained.

[0054] R 5 -(OCH2CH2) m -(OCH2CH(CH3)) n -NH2(4) In formula (4), R 5is a hydrogen atom or an alkyl group having 4 or less carbon atoms. n and m each independently represent 0 or an integer of 1 or more, and m+n represents an integer of 10 or more. The oxyethylene units and oxypropylene units in the molecule of the polyoxyalkyleneamine compound may be arranged randomly or in blocks.

[0055] In formula (4), the value of m / n, which is the ratio of m to n, i.e., the ratio of the amount of oxyethylene units to the amount of oxypropylene units in the molecule of the polyoxyalkyleneamine compound, is preferably 0.05 or more and 10.0 or less, more preferably 0.15 or more and 9.5 or less, and even more preferably 0.70 or more and 9.0 or less. When the value of m / n is within the above range, an ink composition having better gloss and abrasion resistance, and further having better gloss storage stability and ejection stability, tends to be obtained.

[0056] The weight-average molecular weight of the polyoxyalkyleneamine compound is preferably 400 or more and 8000 or less, more preferably 500 or more and 5000 or less, and even more preferably 600 or more and 3000 or less. When the weight-average molecular weight is within the above range, an ink composition tends to be obtained which has better gloss and abrasion resistance, and further has better gloss storage stability and ejection stability. In this specification, the weight-average molecular weight (Mw) refers to a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0057] The content of the polyoxyalkyleneamine compound is preferably 0.005% by mass to 2.0% by mass, more preferably 0.01% by mass to 1.8% by mass, and even more preferably 0.03% by mass to 1.5% by mass, relative to the total amount of the ink composition. When the content of the polyoxyalkyleneamine compound is within the above range, the ink composition tends to have better gloss and abrasion resistance, and also better gloss storage stability and ejection stability.

[0058] 1.3.Binder resin The ink composition of this embodiment contains a binder resin. The binder resin is an acrylic resin having a weight-average molecular weight of 30,000 or less and an acid value of 50 mgKOH / g or less. The content of the binder resin is 0.1% by mass or more and 2.0% by mass or less with respect to the total amount of the ink composition. One type of binder resin may be used alone, or two or more types may be used in combination.

[0059] The acrylic resin may be a copolymer of known polymerizable monomers. Examples of such constituent monomers include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, mono-n-butyl maleate, mono-n-butyl fumarate, and mono-n-butyl itaconate; acrylic acid esters such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate; methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, and 2-ethylhexyl methacrylate; hydroxyl group-containing (meth)acrylic acid esters; amide group-containing monomers; glycidyl group-containing monomers; cyano group-containing monomers; hydroxyl group-containing allyl compounds; tertiary amino group-containing monomers; alkoxysilyl group-containing monomers; and styrene-based compounds. The acrylic resin may be a homopolymer made of a single constituent monomer, or a copolymer made of a plurality of constituent monomers.

[0060] The weight-average molecular weight (Mw) of the acrylic resin is preferably from 1,000 to 20,000, more preferably from 1,500 to 15,000, even more preferably from 2,000 to 10,000, and even more preferably from 2,500 to 7,000. When the weight-average molecular weight is within the above range, an ink composition having better gloss and abrasion resistance, as well as better gloss storage stability and ejection stability, tends to be obtained.

[0061] The acid value of the acrylic resin is preferably 0 mgKOH / g or more and 45 mgKOH / g or less, more preferably 0 mgKOH / g or more and 40 mgKOH / g or less, and even more preferably 0 mgKOH / g or more and 35 mgKOH / g or less. Having an acid value within the above range tends to result in an ink composition having superior gloss and abrasion resistance, as well as superior gloss storage stability and ejection stability. In this specification, "acid value" refers to the number of milligrams of KOH required to neutralize 1 g of resin solids, and can be measured by a method specified in JIS K0070, for example, by electrolytic titration. The titration reagent used here can be, for example, an ethanol solution of sodium hydroxide.

[0062] Commercially available acrylic resins may be used, such as Dianale (registered trademark) BR-113, BR-119, and MB-8096 (all trade names, Mitsubishi Chemical Corporation); Paraloid (registered trademark) B-67MT, XR-34, B-1225, B-99N, B-99, and DM-55 (all trade names, Dow Chemical); and Hi-Los (registered trademark) BS-1144, QS-2067, VS-1057, and BD2010 (all trade names, Seiko PMC Corporation).

[0063] Although commercially available products are listed above, the acrylic resin may also be obtained by synthesis using a conventional method.

[0064] The content of the binder resin is preferably from 0.005% to 0.70% by mass, and more preferably from 0.5% to 1.8% by mass, relative to the total amount of the ink composition. When the content of the binder resin is within the above range, the ink composition tends to have better gloss and abrasion resistance, and also better gloss storage stability and ejection stability.

[0065] 1.4.Liquid medium components The ink composition of this embodiment contains a liquid medium component. The liquid medium component is a component that is liquid by itself and functions primarily as a dispersion medium for dispersing the glitter pigment. Furthermore, the use of the liquid medium component can make it easier for the ink composition to adhere to the recording medium. The liquid medium component may be used alone or in combination of two or more types.

[0066] Examples of the liquid medium component include water and various organic solvents. Ink compositions commonly used in inkjet recording systems include aqueous ink compositions that use water as the primary solvent and solvent ink compositions that use an organic solvent as the primary solvent, i.e., non-aqueous ink compositions. Non-aqueous ink compositions preferably contain 5.0% or less by mass of water, more preferably 3.0% or less by mass, and even more preferably 1.0% or less by mass. Solvent ink compositions are broadly classified into two types: real solvent (high solvent) ink compositions and eco-solvent (low solvent) ink compositions. Eco-solvent ink compositions are solvent ink compositions in which colorants are dispersed in organic solvents that are low in odor and considerate to humans and the environment. The organic solvents used in eco-solvent ink compositions are characterized by not falling under the organic solvents defined by the Industrial Safety and Health Act, not falling under the Class 1 or Class 2 organic solvents defined in the Organic Solvent Poisoning Prevention Rules, or not subject to the requirement for local exhaust ventilation systems in indoor workplaces as defined by the Fire Service Act.

[0067] The ink composition according to this embodiment is a non-aqueous ink composition, and is preferably an eco-solvent ink composition.

[0068] Examples of organic solvents include alcohols; hydrocarbon compounds; ether compounds; ketones; esters; and polar compounds such as propylene carbonate, N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, cyclohexanone, and acetonitrile.

[0069] Examples of alcohols include monohydric alcohols such as methanol, ethanol, propanol, isopropanol, and butanol; and polyhydric alcohols such as ethylene glycol, propylene glycol, and 1,2-hexanediol.

[0070] Examples of hydrocarbon compounds include n-heptane, n-octane, decane, dodecane, tetradecane, toluene, xylene, cymene, durene, indene, dipentene, tetrahydronaphthalene, decahydronaphthalene, and cyclohexylbenzene.

[0071] Examples of ether compounds include glycol ethers. Examples of glycol ethers 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, and bis(2-methoxyethyl)ether. Other examples of ethers include p-dioxane and tetrahydrofuran.

[0072] Ketones include, for example, acetone, methyl ethyl ketone, isophorone, and diethyl ketone.

[0073] Examples of esters include ethyl acetate, propyl acetate, butyl acetate, methyl levulinate, ethyl levulinate, isoamyl isovalerate, isoamyl butyrate, isoamyl acetate, butyl 2-methylvalerate, allyl heptanoate, and ethyl 2-methylvalerate; and cyclic esters, such as lactones such as γ-butyrolactone, ε-caprolactone, and γ-valerolactone.

[0074] The organic solvent preferably contains one or more selected from the group consisting of ether compounds and esters, more preferably one or more selected from the group consisting of glycol ethers and cyclic esters, even more preferably one or more selected from the group consisting of diethylene glycol diethyl ether, tetraethylene glycol monobutyl ether, and γ-butyrolactone, and even more preferably all of diethylene glycol diethyl ether, tetraethylene glycol monobutyl ether, and γ-butyrolactone. When the organic solvent contains any of the above solvents, an ink composition having better gloss and abrasion resistance, and also better gloss storage stability and ejection stability tends to be obtained.

[0075] The content of the liquid medium components relative to the total amount of the ink composition is preferably 60.0% by mass or more and 99.7% by mass or less, more preferably 70.0% by mass or more and 99.5% by mass or less, and even more preferably 75.0% by mass or more and 99.0% by mass or less. When the content of the liquid medium components is within the above range, an ink composition having better gloss and abrasion resistance, and also better gloss storage stability and ejection stability tends to be obtained.

[0076] 1.5.Viscosity control resin The ink composition of this embodiment preferably contains a viscosity adjusting resin. The viscosity adjusting resin has a weight average molecular weight of 3,000 or less. The viscosity adjusting resin is one or more types selected from the group consisting of ketone resins, rosin-modified resins, and coumarone resins. The viscosity adjusting resins may be used alone or in combination of two or more types.

[0077] When the ink composition contains a viscosity adjusting resin, the ink composition tends to have better gloss and abrasion resistance, and also has better gloss storage stability and ejection stability. In particular, when the ink composition contains a viscosity adjusting resin, the fluidity of the ink composition can be more assured, so that better ink ejection properties can be obtained and high-frequency printing can be more easily performed.

[0078] The weight-average molecular weight (Mw) of the viscosity adjusting resin is preferably from 500 to 2,500, more preferably from 700 to 1,500. When the weight-average molecular weight is within the above range, an ink composition tends to be obtained that has even better gloss, abrasion resistance, gloss storage stability, and ejection stability, and that makes it easier to perform high-frequency printing.

[0079] The viscosity adjusting resin preferably has an acid value of 0 mgKOH / g or more and 30 mgKOH / g or less, more preferably 0 mgKOH / g or more and 25 mgKOH / g or less, and even more preferably 0 mgKOH / g or more and 20 mgKOH / g or less. When the acid value is within the above range, an ink composition having even better gloss, abrasion resistance, gloss storage stability, and ejection stability tends to be obtained, which makes it easier to perform high-frequency printing.

[0080] Known resins can be used as the ketone resin. Examples of such ketone resins include formaldehyde resins, cyclohexanone-formaldehyde resins, and ketone aldehyde condensation resins. The ketone resin preferably includes a ketone aldehyde condensation resin. Use of a ketone aldehyde condensation resin tends to result in an ink composition that has even better gloss, abrasion resistance, gloss storage stability, and ejection stability, and that can more easily perform high-frequency printing.

[0081] The ketone resin may be a commercially available product, such as TEGO (registered trademark) VariPlus AP, CA, SK, and 1201 (all trade names, Evonik Operations GmbH).

[0082] Known resins can be used as the rosin-modified resin. Examples of such rosin-modified resins include maleated rosin, fumarated rosin, rosin-modified maleic acid resin, rosin-modified fumaric acid resin, rosin-modified phenolic resin, rosin-modified alkyd resin, and rosin-modified ester resin. The rosin-modified resin preferably includes a rosin-modified ester resin. Use of a rosin-modified ester resin tends to result in an ink composition that has even better gloss, abrasion resistance, gloss storage stability, and ejection stability, and that can more easily perform high-frequency printing.

[0083] Commercially available rosin-modified resins may be used, such as Ester Gum AAL, A, AAV, 105, AT, H, HP, and HD, and Super Ester A75, A100, A115, and A125 (all trade names, manufactured by Arakawa Chemical Industries, Ltd.); Harie Star TF, S, C, DS70L, DS90, and DS130 (all trade names, manufactured by Harima Chemical Group, Ltd.).

[0084] Known resins can be used as the coumarone resin. Examples of such coumarone resins include coumarone-indene resins and coumarone-indene-styrene copolymers. The coumarone resin preferably contains coumarone-indene resin. Use of coumarone-indene resin tends to result in an ink composition that has even better gloss, abrasion resistance, gloss storage stability, and ejection stability, and that can more easily perform high-frequency printing.

[0085] Commercially available coumarone resins may be used, such as coumarone resin (Kobe Oil Chemical Industry Co., Ltd.), Knitrange (registered trademark) coumarone G90, G-100N, V-120, and V-120S (all trade names, Nitto Range Co., Ltd.), and H-100, WS-100G, WS-100H, WS-120V, and WS-100GC (all trade names, Nitto Chemical Co., Ltd.).

[0086] Although commercially available products are listed above, the viscosity adjusting resins may also be obtained by synthesis using conventional methods.

[0087] The content of the viscosity adjusting resin is preferably 0.1% by mass or more and 5.0% by mass or less, more preferably 0.3% by mass or more and 4.0% by mass or less, based on the total amount of the ink composition. When the content of the viscosity adjusting resin is within the above range, the ink composition tends to have even better gloss, abrasion resistance, gloss storage stability, and ejection stability, and to be able to more easily perform high-frequency printing.

[0088] 1.6.Other resins The ink composition of this embodiment preferably contains another resin (hereinafter simply referred to as "other resin") that is different from the binder resin. The other resin is also different from the viscosity adjusting resin. The weight average molecular weight of the other resin is 15,000 or less. The content of the other resin is 1.5% by mass or less with respect to the total amount of the ink composition. The other resin may be used alone or in combination of two or more types.

[0089] When the ink composition contains other resins, the ink composition tends to have better gloss, and also has better gloss storage stability and ejection stability. In particular, when the ink composition contains other resins, the ink composition tends to be able to impart even better abrasion resistance to the recording medium.

[0090] The weight-average molecular weight (Mw) of the other resin is preferably from 500 to 10,000, and more preferably from 1,000 to 8,000. When the weight-average molecular weight is within the above range, an ink composition tends to be obtained that has even better gloss, gloss storage stability, and ejection stability, as well as even better abrasion resistance.

[0091] The acid value of the other resin is preferably 0 mgKOH / g or more and 50 mgKOH / g or less, more preferably 0.5 mgKOH / g or more and 40 mgKOH / g or less. When the acid value is in the above range, an ink composition tends to be obtained which has even better gloss, gloss storage stability, and ejection stability, as well as even better abrasion resistance.

[0092] As the other resin, known resins can be used. Examples of such resins include polyester resins, urethane resins, and addition polymerization resins. These resins are often handled in emulsion form, i.e., resin dispersions, but may also be supplied in powder form.

[0093] The other resin preferably includes a polyester resin. By using a polyester resin, an ink composition tends to be obtained that has even better gloss, gloss storage stability, and ejection stability, as well as even better abrasion resistance.

[0094] Examples of polyester resins include resins having structural units derived from polycarboxylic acids and structural units derived from polyhydric alcohols.

[0095] Examples of polycarboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 4,4'-diphenyldicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2-potassium sulfoterephthalic acid, 5-sodium sulfoisophthalic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, glutaric acid, succinic acid, trimellitic acid, trimesic acid, pyromellitic acid, trimellitic anhydride, phthalic anhydride, succinic anhydride, and p-hydroxybenzoic acid, as well as salts thereof, such as potassium salts, sodium salts, calcium salts, and magnesium salts.

[0096] Examples of polyhydric alcohols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-propanediol, 1,3-butylene glycol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,5-pentanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, p-xylylene glycol, bisphenol A-ethylene glycol adduct, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polytetramethylene oxide glycol, dimethylolpropionic acid, glycerin, trimethylolpropane, sodium dimethylolethylsulfonate, potassium dimethylolethylsulfonate, and potassium dimethylolpropionate.

[0097] The polyester resin preferably contains a hydroxy group, a carboxy group, a sulfonic acid group, or a sodium salt thereof. The polyester resin may contain one or more of these groups.

[0098] Commercially available polyester resins may be used, such as Vylon (registered trademark) 220, 226, 237, 240, 296, 660, 680, 802, 822, 885, GK130, GK140, GK-150, GK-250, GK-590, GK-680, GK-810, and GK890 (all trade names, manufactured by Toyobo Co., Ltd.); TEGO (registered trademark) Addbond LTH (trade name, manufactured by Evonik Operations GmbH).

[0099] Although commercially available products are listed above, the polyester resin may also be obtained by synthesis using a conventional method.

[0100] Urethane resin is a general term for resins containing urethane bonds. Examples of urethane resins include polyether urethane resins containing ether bonds in the main chain in addition to urethane bonds, polyester urethane resins containing ester bonds in the main chain, and polycarbonate urethane resins containing carbonate bonds in the main chain.

[0101] Examples of addition polymerization resins include homopolymers or copolymers of (meth)acrylic acid, (meth)acrylic acid esters, acrylonitrile, cyanoacrylate, acrylamide, olefin, styrene, silicone, rosin, terpene, epoxy, polyester, vinyl acetate, vinyl chloride, vinyl alcohol, vinyl ether, vinylpyrrolidone, vinylpyridine, vinylcarbazole, vinylimidazole, and vinylidene chloride.

[0102] The content of the other resin is preferably 0.1% by mass or more and 1.3% by mass or less, and more preferably 0.5% by mass or more and 1.2% by mass or less, based on the total amount of the ink composition. When the content of the other resin is within the above range, an ink composition tends to be obtained that has even better gloss, gloss storage stability, and ejection stability, as well as even better abrasion resistance.

[0103] 1.7.Other Ingredients The ink composition may contain various additives that are typically used in ink compositions, other than the above components, such as a surface treatment agent, a leveling agent, a polymerization accelerator, a polymerization inhibitor, a photopolymerization initiator, a dispersant, a surfactant, a penetration accelerator, a moisturizer, a colorant, a fixing agent, an antifungal agent, a preservative, an antioxidant, a chelating agent, a thickener, and a sensitizer. The additives may be used alone or in combination of two or more.

[0104] Examples of surfactants include acetylene glycol surfactants, silicone surfactants, and fluorine surfactants.

[0105] The content of the additives is preferably 0.01% by mass or more and 10.0% by mass or less in total relative to the total amount of the ink composition.

[0106] 1.8. Method for producing ink composition The ink composition can be prepared by mixing a glitter pigment, a polyoxyalkyleneamine compound, a binder resin, a liquid medium component, and optionally a viscosity adjusting resin, other resins, and other components in any order, and then removing impurities and foreign matter by filtration or the like as necessary. The components can be mixed by sequentially adding the components to a container equipped with a stirring device such as a mechanical stirrer or a magnetic stirrer, stirring, and mixing them. Filtration methods include centrifugal filtration and filter filtration.

[0107] 2. Inkjet recording method The inkjet recording method of this embodiment includes a step of depositing an ink composition onto a recording medium. Specifically, the inkjet recording method includes a step of ejecting the ink composition from an inkjet head and depositing it onto the recording medium. FIG. 1 shows an example of the inkjet recording method of this embodiment. This inkjet recording method includes, in this order, an ink depositing step and a heating step. Next, the ink depositing step, the recording medium, and an inkjet recording apparatus that can be used in the recording method will be described.

[0108] 2.1.Ink application process The ink deposition step is a step of depositing an ink composition onto a recording medium using an inkjet method. Discharge of the ink composition by the inkjet method can be carried out using a known inkjet recording device. Discharge methods that can be used include a piezo method and a method of discharging ink by heating the ink to generate bubbles.

[0109] 2.2. Recording medium Examples of recording media include absorbent recording media, low absorbent recording media, and non-absorbent recording media. Among these, low absorbent recording media and non-absorbent recording media are preferred for use with solvent-based inks.

[0110] Examples of absorbent recording media include plain paper such as electrophotographic paper that has high ink composition permeability; inkjet paper, i.e., inkjet paper having an ink absorbing layer made of silica particles or alumina particles, or an ink absorbing layer made of a hydrophilic polymer such as polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP); and recording media having a paper support.

[0111] A recording medium with low ink absorption or no ink absorption refers to a recording medium that does not absorb the ink composition at all or absorbs almost no ink. Quantitatively, a recording medium with low ink absorption is one that absorbs ink within 30 msec from the start of contact in the Bristow method. 1 / 2 Water absorption up to 10mL / m 2 This refers to a recording medium that is either: "absorbent" or "low-absorbent." The Bristow method is the most widely used 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 (JAPAN TAPPI). Details of the test method are described in Standard No. 51 "Paper and Paperboard - Liquid Absorbency Test Method - Bristow Method" of the "JAPAN TAPPI Paper and Pulp Test Methods 2000 Edition." In contrast, ink-absorbent recording media refers to recording media that do not fall into the category of non-absorbent or low-absorbent.

[0112] Examples of non-ink-absorbing recording media include plastic films that do not have an ink-absorbing layer, substrates such as paper coated with plastic, and substrates with a plastic film adhered thereto. Examples of plastics include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, and polypropylene.

[0113] Furthermore, examples of recording media with low ink absorption include recording media having a coating layer on the surface for receiving ink. Examples of such recording media include those having a paper substrate such as printing paper, art paper, coated paper, and matte paper. When the substrate is a plastic film, examples include those having a hydrophilic polymer coated on the surface of polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene, etc., and those having particles of silica, titanium, etc. coated together with a binder.

[0114] In addition to the above-mentioned recording media, recording media that are non-ink-absorbent or have low ink-absorbent properties, such as metal plates made of iron, silver, copper, aluminum, etc., and glass, can also be used.

[0115] 2.3. Inkjet recording device The inkjet recording apparatus can be either a serial type or a line type. These types of inkjet recording apparatuses are equipped with an inkjet head, and while changing the relative positional relationship between the recording medium and the inkjet head, droplets of an ink composition are ejected from the nozzle holes of the inkjet head at a predetermined timing and in a predetermined volume (mass), thereby depositing the ink composition on the recording medium to form a predetermined image.

[0116] The inkjet recording apparatus can employ any known configuration, such as a drying unit, a roll unit, a winding unit, etc. The inkjet recording apparatus may have, for example, a transport means for transporting the recording medium, an image layer forming means for recording an image using an ink composition, a drying means, and an overall drying means for heating and blowing air onto the recording surface.

[0117] The conveying means is, for example, composed of a roller. In this case, it may have multiple rollers. Another method is to convey the recording medium by adhering it to or absorbing it on a rubber belt or the like. The position and number of conveying means can be arbitrarily selected as long as the recording medium can be conveyed. The conveying means may include a roll mechanism, a tray, various platens, and the like.

[0118] The image layer forming unit ejects an ink composition onto the recording surface of the recording medium to form an image layer. The image layer forming unit includes an inkjet head with nozzles, and a nozzle row is assigned to each predetermined composition.

[0119] The drying means can be used to heat and dry the image layer formed on the recording surface and / or remove volatile components from the recording medium. The drying means may be located anywhere, taking into consideration the timing of the deposition process, the transport path of the recording medium, and the like. Examples of image layer drying means include a method of applying heat to the recording medium by platen heating or the like, a method of blowing air onto the image on the recording medium, and a combination of these methods. Specific examples of means used in these methods include forced air heating, radiant heating, conductive heating, high-frequency drying, and microwave drying. [Example]

[0120] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these. Unless otherwise specified, "parts" below refer to parts by mass.

[0121] 1. Preparation of Non-Aqueous Inkjet Ink Composition (Examples 1 to 28 and Comparative Examples 1 to 6) First, a 20 μm thick polyethylene terephthalate film with a smooth surface and a surface roughness Ra of 0.02 μm or less was prepared. Next, a release resin solubilized in acetone was coated on the entire surface of one side of the film using a roll coater to form a release layer.

[0122] A polyethylene terephthalate film with a release layer formed on it was transported into a vacuum deposition device at a speed of 5 m / s, and aluminum (Al) was deposited on the film under reduced pressure to form a 15 nm thick film composed of Al.

[0123] A polyethylene terephthalate film having an Al film formed thereon was immersed in tetrahydrofuran, and ultrasonic vibrations of 40 kHz were applied to obtain dispersion liquid 1 containing metal particles made of Al.

[0124] Tetrahydrofuran was removed from Dispersion Liquid 1 using a centrifuge, and then diethylene glycol diethyl ether was added to obtain Suspension Liquid 1 having a metal particle content of 5.0 mass %.

[0125] The obtained suspension 1 was treated with a circulating high-power ultrasonic crusher to crush the metal particles to a predetermined size, thereby obtaining suspension 2. In the treatment, ultrasonic waves of 20 kHz were applied.

[0126] To the obtained suspension 2, 0.45 parts by mass of a polyoxyalkyleneamine compound represented by the above formula (4) was added per 1.5 parts by mass of metal particles, and the mixture was subjected to heat treatment at 55°C for 1 hour under 40 kHz ultrasonic irradiation to break up the agglomerations of the metal particles and disperse the metal particles in the state of primary particles, thereby obtaining dispersion liquid 2. The polyoxyalkyleneamine compound used was a block copolymer in which an amino group is bonded to the end of consecutive oxyethylene units and a methyl group is bonded to the end of consecutive oxypropylene units, which satisfies the condition that m / n is 6.3 between m and n in the above formula (4) and has a weight-average molecular weight of 1,000.

[0127] To the obtained dispersion 2, 0.09 parts by mass of a surface treatment agent was added relative to 1.5 parts by mass of metal particles to obtain dispersion 3. The surface treatment agent was a compound represented by the formula (1) above, in which A is a hydrogen atom and R 1 is an n-octadecyl group, and a is 1; and a compound represented by the above formula (1) in which E in the above formula (2) is a hydrogen atom and R 2A mixture of a compound represented by the above formula (2) in which is an n-octadecyl group and b is 2 was used.

[0128] The obtained dispersion 3 was subjected to heat treatment at 55°C for 3 hours under irradiation with 28 kHz ultrasound to react with the surface treatment agent on the surfaces of the metal particles, thereby obtaining dispersion 4 of a bright pigment surface-modified with the surface treatment agent. The bright pigment contained in dispersion 4 was scaly, with a volume average particle diameter of 0.50 μm and an average thickness of 15 nm.

[0129] The liquid medium components were added to the obtained dispersion 4, and further an acrylic resin was added as a binder resin to obtain a non-aqueous inkjet ink composition according to Example 1 having the composition shown in Table 1.

[0130] In addition, non-aqueous inkjet ink compositions according to Examples 2 to 28 and Comparative Examples 1 to 6 were obtained in the same manner as in Example 1, except that the obtained dispersion 4 was changed to have the composition shown in Tables 1 to 4.

[0131] The numerical values in each example in Tables 1 to 4 indicate mass %. The mass % of the binder resin is shown as a solid content. Mw indicates the weight average molecular weight. The numerical value of the acid value indicates mgKOH / g. The components shown in Tables 1 to 4 are as follows.

[0132] [Brilliant pigment] Aluminum: Aluminum particles

[0133] [Surface treatment agent] Mixture: A mixture of a compound represented by formula (1) and a compound represented by formula (2)

[0134] [Polyoxyalkyleneamine Compound] A compound represented by formula (4)

[0135] [Acrylic resin (binder resin)] BR113: Dianal (registered trademark) BR113 (trade name, Mitsubishi Chemical Corporation), Mw: 30,000, acid value: 0 mgKOH / g BD2010: Hi-Loss (registered trademark) BD2010 (product name, Seiko PMC Corporation), Mw: 12,000, acid value: 0 mgKOH / g DM-55: Paraloid (registered trademark) DM-55 (trade name, Dow Chemical), Mw: 6,000, acid value: 0 mg KOH / g VS-1057: Hi-Loss (registered trademark) VS-1057 (product name, Seiko PMC Corporation), Mw: 19,000, acid value: 40 mg KOH / g

[0136] [Acrylic resin] UC3000: Alphon (registered trademark) UC3000 (product name, Toagosei Co., Ltd.), Mw: 10,000, acid value: 74 mg KOH / g B60: Paraloid (registered trademark) B-60 (trade name, Dow Chemical), Mw: 50,000, acid value: 0 mg KOH / g

[0137] [Polyester resin (other resin)] Byron 802: Byron (registered trademark) 802 (product name, Toyobo Co., Ltd.), Mw: 3,000, acid value: 1 mgKOH / g LTH: TEGO® Addbond LTH (trade name, Evonik Operations GmbH), Mw: 5,000, acid value: 30 mg KOH / g

[0138] [Viscosity adjusting resin] (ketone resin) AP: TEGO® VariPlus AP (trade name, Evonik Operations GmbH), ketone-aldehyde condensation resin, Mw: 1,000, acid value: 0 mg KOH / g CA: TEGO® VariPlus CA (trade name, Evonik Operations GmbH), ketone-aldehyde condensation resin, Mw: 950, acid value: 0 mg KOH / g (rosin-modified resin) DS70L: Harie Star DS70L (product name, Harima Chemical Group Co., Ltd.), rosin-modified ester resin, Mw: 970, acid value: 8 mg KOH / g Hari-S: Harie Star S (product name, Harima Chemical Group Co., Ltd.), rosin-modified ester resin, Mw: 750, acid value: 15 mg KOH / g (coumarone resin) G90...Knitrange (registered trademark) Coumarone G90 (product name, Nitto Range Co., Ltd.), Coumarone-indene resin, Mw: 750, acid value: 0 mg KOH / g

[0139] [Liquid medium component] DEDG: Diethylene glycol diethyl ether BTGH: Tetraethylene glycol monobutyl ether BL: γ-butyrolactone

[0140] 2. Evaluation Method 2.1.Gloss Each of the non-aqueous inkjet ink compositions of Examples 1 to 28 and Comparative Examples 1 to 6 was filled into the cartridge of an inkjet printer SC-S80650 (Seiko Epson Corporation). Thereafter, under printing conditions where the printing temperature of the platen heater was 40°C, the temperature of the drying heater was 45°C, and the printing frequency was 12 kHz, the ink composition was applied in a solid pattern to a recording medium, solvent inkjet media OREJET (registered trademark) 3165G (manufactured by ORAFOL), at a resolution of 720 dpi x 720 dpi, with ink ejection volumes of 80, 90, and 100% duty, to form an image. The 20-degree gloss of this image was measured using a gloss meter HG-268 (trade name, Suga Test Instruments Co., Ltd.). The gloss was evaluated according to the following evaluation criteria based on the highest G value obtained from 80, 90, and 100% duty. The results are shown in Tables 5 to 8. In Tables 5 to 8, the G value is also shown along with the evaluation results. (standard) A:G value exceeds 550. B:G value is over 450 and 550 or less. The C:G value is greater than 350 and less than 450. D:G value is 350 or less.

[0141] 2.2.Abrasion resistance For each of the images obtained in the gloss evaluation, rub resistance was evaluated in accordance with JIS K5701:2000 using a Gakushin-type rub fastness tester AB-301 (trade name, manufactured by Tester Sangyo Co., Ltd.). Specifically, a polyvinyl chloride sheet was placed on the image surface, and the image was rubbed 20 times with a 500 g load. After rubbing, peeling of the image surface and transfer of ink to the sheet were visually confirmed, and rub resistance was evaluated according to the following evaluation criteria. The results are shown in Tables 5 to 8. (standard) A: There were few scratches on the image surface, and the image clarity remained the same as before rubbing. B: There were no scratches on the image surface, but the image clarity was reduced. C: There were slight scratches on the printed surface and noticeable stains on the sheet. D: The printed surface was significantly damaged, exposing the underlying solvent inkjet media.

[0142] 2.3. Gloss storage stability After leaving the ink composition at 60°C for 5 days, an image was formed using the same method as in the gloss evaluation above, and the 20° gloss of the image was measured using a gloss meter HG-268 (trade name, Suga Test Instruments Co., Ltd.). The gloss was evaluated according to the following evaluation criteria based on the decrease in the obtained G value due to leaving and visual observation. The results are shown in Tables 5 to 8. (standard) A: The decrease in G value was 30 or less, and almost no change in gloss was observed. B: The decrease in the G value was more than 30 but not more than 60, and the image clarity was slightly decreased. The C:G value decreased from over 60 to 120 or less, the image clarity decreased, and the image appeared slightly cloudy. D: The G value decreased by more than 120, the image clarity decreased significantly, and the image appeared yellowish.

[0143] 2.4.Discharge stability Each of the non-aqueous inkjet ink compositions of Examples 1 to 28 and Comparative Examples 1 to 6 was filled into the cartridge of an inkjet printer SC-S80650 (Seiko Epson Corporation). Next, a droplet ejection device was prepared in a chamber (thermal chamber), and a non-aqueous inkjet ink composition was continuously ejected for 30 seconds from an inkjet head equipped with 400 nozzles at 20 kHz under conditions of 10 pL per droplet, with the piezoelectric element drive waveform optimized, at 10°C and 40% RH. The droplet ejection status was then photographed using a droplet strobe illumination and an ejection evaluation device equipped with a CCD camera. The number of defective nozzles after 30 seconds of continuous ejection was determined from the obtained images. Note that nozzles were judged to be defective if the obtained images showed missing ejections (missing nozzles), bending (angle change of 25% or more), timing delays, or size changes. The ejection stability was evaluated according to the following evaluation criteria based on the ratio of defective nozzles to 400 nozzles. The results are shown in Tables 5 to 8. (standard) A: The number of defective nozzles was 1% or less. B: The number of defective nozzles was more than 1% but not more than 3%. C: The number of defective nozzles exceeded 3%.

[0144] As shown in Tables 5 to 8, it was found that the ink composition of this embodiment can provide an ink composition having excellent gloss and abrasion resistance. It was also found that the ink composition of this embodiment can provide an ink composition further having excellent gloss storage stability and ejection stability.

[0145] Furthermore, a comparison between Examples 3 and 4 revealed that when an acrylic resin having a weight-average molecular weight of 7,000 or less was used as the binder resin, an ink composition having excellent abrasion resistance and even better gloss could be obtained.

[0146] A comparison of Examples 1 to 8 and 9 to 20 revealed that the use of a viscosity adjusting resin makes it possible to obtain an ink composition that has excellent gloss and abrasion resistance as well as better ejection stability.

[0147] The results of Examples 21 to 28 show that when a polyester resin is used as the resin other than the binder resin, an ink composition having excellent gloss and even better abrasion resistance can be obtained.Furthermore, the results of Examples 21 to 28 show that when a polyester resin having an acid value of 20 mgKOH / g or more is used as the resin other than the binder resin, an ink composition having excellent gloss and even better abrasion resistance can be obtained.

Claims

1. An ink composition comprising a bright pigment, a polyoxyalkyleneamine compound, a binder resin, and a liquid medium component, the bright pigment is composed of metal particles whose surfaces have been modified with a surface treatment agent, the surface treatment agent is at least one selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2), the binder resin is an acrylic resin having a weight average molecular weight of 30,000 or less and an acid value of 50 mgKOH / g or less, The non-aqueous inkjet ink composition has a binder resin content of 0.1% by mass or more and 2.0% by mass or less relative to the total amount of the ink composition. (A-R 1 -O) a P(O)(OH) 3-a (1) (In formula (1), A is a hydrogen atom, a carboxyl group, a hydroxyl group, an amino group, or an oxyalkylene-containing group; R 1 is a divalent hydrocarbon group having 10 or more carbon atoms, and a is 1 or 2. (E-R 2 ) b P(O)(OH) 3-b (2) (In formula (2), E is a hydrogen atom, a carboxyl group, a hydroxyl group, an amino group, or an oxyalkylene-containing group; R 2 is a divalent hydrocarbon group having 10 or more carbon atoms, and b is 1 or 2.

2. Further comprising a viscosity adjusting resin; The viscosity adjusting resin has a weight average molecular weight of 3,000 or less, 2. The ink composition according to claim 1, wherein the viscosity adjusting resin is at least one selected from the group consisting of ketone resins, rosin-modified resins, and coumarone resins.

3. Further containing another resin different from the binder resin, the weight average molecular weight of the other resin is 15,000 or less, The ink composition according to claim 1 , wherein the content of the other resin is 1.5% by mass or less with respect to the total amount of the ink composition.

4. The ink composition according to claim 3 , wherein the other resin comprises a polyester resin.

Images