Non-aqueous inkjet ink composition and recording method

Abstract

To provide a non-aqueous ink jet ink composition that can achieve both satisfactory glossiness and a satisfactory property of reducing unevenness at the same time.SOLUTION: A non-aqueous ink jet ink composition according to an embodiment of the present disclosure contains a bright pigment, and glycol monoether A and glycol monoether B that are represented by Formula (1) and have flash points different from each other, in which the glycol monoether A has a flash point of 85°C or lower, the glycol monoether B has a flash point of 95°C or higher, a total content of the glycol monoether A and the glycol monoether B is in a range of 20 to 60 mass% with respect to a total amount of the ink composition, and the content of the glycol monoether A is greater than the content of the glycol monoether B. R1-(O-R2)n-OH...Formula (1) (In Formula (1), R1 represents an alkyl group having 1 to 8 carbon atoms or a phenyl group, R2 represents an alkylene group having 1 to 5 carbon atoms, and n represents an integer of 1 to 4.)SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a non-aqueous inkjet ink composition and a recording method. [Background technology]

[0002] Inkjet recording methods, which enable the recording of high-resolution images with relatively simple equipment, are undergoing rapid development in various fields. In recent years, there has been a demand for high-speed printing of even higher-resolution images by applying smaller droplets of ink or other liquids at high density. In this context, attempts are being made to record images with metallic luster, and the development of metallic inks that will enable even higher gloss printing is progressing.

[0003] For example, Patent Document 1 discloses a non-aqueous inkjet ink composition containing a luminous pigment, a specific glycol diether having a flash point of 70°C or lower, and a specific glycol monoether. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2016-150984 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, the glossiness of the resulting recordings was still insufficient, and when printing color inks on top of metallic ink images, unevenness occurred at higher printing speeds. In other words, good glossiness and good reduction of unevenness could not be achieved simultaneously. [Means for solving the problem]

[0006] One embodiment of the non-aqueous inkjet ink composition according to the present invention is: Luminous pigments and, It contains glycol monoether A and glycol monoether B, which are represented by the following formula (1) and have different flash points. The flash point of the glycol monoether A is 85°C or lower. The flash point of the glycol monoether B is 95°C or higher. The total content of glycol monoether A and glycol monoether B is 20 to 60% by mass relative to the total amount of the ink composition. The content of glycol monoether A is greater than the content of glycol monoether B. R1-(O-R2) n -OH...Formula (1) (In formula (1), R1 is an alkyl group or phenyl group having 1 to 8 carbon atoms, R2 is an alkylene group having 1 to 5 carbon atoms, and n is an integer from 1 to 4.)

[0007] One aspect of the recording method according to the present invention is: The present invention comprises a step of ejecting the non-aqueous inkjet ink composition according to one embodiment described above by an inkjet method and adhering it to a recording medium. [Brief explanation of the drawing]

[0008] [Figure 1] A schematic diagram of an example of a recording device that can be used in the recording method according to the present invention. [Modes for carrying out the invention]

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

[0010] 1. Non-aqueous inkjet ink composition A non-aqueous inkjet ink composition according to one embodiment of the present invention contains a glossy pigment and glycol monoether A and glycol monoether B represented by the following formula (1), which have different flash points, wherein the flash point of glycol monoether A is 85°C or lower, and the flash point of glycol monoether B is 95°C or higher, the total content of glycol monoether A and glycol monoether B is 20 to 60% by mass of the total amount of the ink composition, and the content of glycol monoether A is greater than the content of glycol monoether B. R1-(O-R2) n -OH...Formula (1) (In formula (1), R1 is an alkyl group or phenyl group having 1 to 8 carbon atoms, R2 is an alkylene group having 1 to 5 carbon atoms, and n is an integer from 1 to 4.)

[0011] Traditionally, metallic printing involved increasing the pigment size of metallic inks as much as possible within the range of ink ejection, and allowing sufficient drying time for the ink at a relatively slow printing speed. In other words, because larger pigment sizes are relatively large relative to the nozzle holes of the inkjet head, high-frequency printing stability is reduced, necessitating a reduction in printing speed. This is partly due to the difficulty in uniformly miniaturizing metallic pigments to extremely fine sizes, and the low productivity and time-consuming nature of the grinding process. Furthermore, while larger pigment sizes allow for the formation of seamless, continuous reflective surfaces, thus easily achieving high gloss, fluidity is sacrificed. As a result, the ability to arrange the pigments appropriately on the recording medium surface during ink drying (hereinafter also referred to as "leafing ability" or "orientation ability") is not sufficiently high, making it difficult to resolve pigment overlaps under fast drying conditions, which is another reason for the need for extended drying time. However, this method does not enable high-speed printing, and moreover, the gloss is still not sufficient.

[0012] In recent years, in the inkjet recording method, there has been an increasing demand for applying finer droplets of ink or the like at high density to print higher-definition images at high speed. Therefore, even in the case of metallic ink, there is a need for a product that has excellent glossiness even when printing with high definition by making the size of the pigment smaller and even when printing at high speed. However, it has been difficult to achieve higher glossiness than before for the following reasons.

[0013] (i) Reduction in pigment particle size: When the size of the lustrous pigment is made smaller to cope with high-definition printing, the aspect ratio of the pigment tends to become smaller. Although such pigments have good fluidity particle by particle, it becomes difficult to form a reflection surface with few seams parallel to the printing surface, so the glossiness is likely to be inferior. Also, in terms of dispersibility, since the relative specific surface area with respect to the particle weight increases, the repulsive force between particles weakens due to the influence of heat, moisture, etc., and the dispersion performance is likely to decrease, and the leafing is inhibited due to the aggregation of the pigment, resulting in a decrease in glossiness. (ii) Expansion of the recording medium due to solvent penetration: Generally, metallic ink contains a glycol ether-based solvent (and in some cases, a further polar solvent) as a solvent. These solvents have the effect of swelling the surface of the recording medium and imparting adhesion to the ink. On the other hand, unevenness occurs on the surface of the recording medium due to the swelling, and the glossiness (especially the gloss at a low angle such as 20 degrees) is likely to decrease. (iii) Drying speed: In high-definition printing, since the ejected ink droplets are finer, the ink dries quickly on the recording medium, and it is difficult to secure sufficient time for leafing. On the other hand, when overprinting a color ink on top of an image printed with metallic ink, especially in the case of high-speed printing, in order to reduce bleeding, unevenness, and in some cases, color mixing or fading in the color printing due to re-dissolution in the upper color printing, the underlying metallic layer needs to dry quickly. That is, in order to obtain high glossiness, it is necessary to lower the drying speed, while in order to reduce unevenness, it is necessary to increase the drying speed, so it has been difficult to achieve both.

[0014] On the other hand, the non-aqueous inkjet ink composition according to the present embodiment contains a specific glycol monoether in a specific quantitative relationship, thereby reducing the unevenness due to swelling of the recording medium while maintaining appropriate adhesion, making the drying speed of the ink appropriate, and achieving high glossiness and good reduction of unevenness. By containing the glycol monoether A, the drying property of the ink can be improved well, the influence on the recording medium such as swelling can be suppressed, and appropriate adhesion can be obtained. In addition, the glycol monoether B contributes to reducing the drying property of the ink well and ensuring the time for the pigment to leaf. In addition, since the glycol monoether B can reduce the drying of the nozzle and improve the intermittent printing stability, the printing accuracy can be kept high. By making the content of the glycol monoether A more than the content of the glycol monoether B in this way, an appropriate drying speed can be obtained, and high glossiness and good reduction of unevenness can be obtained.

[0015] In the present invention, "non-aqueous" means that it does not have water as the main solvent component and does not contain water as a functional component for the ink to exhibit its functions and performance. The water content in the total amount of the non-aqueous inkjet ink composition is 5% by mass or less, preferably 3% by mass or less, more preferably 1% by mass or less, particularly preferably 0.5% by mass or less, more preferably 0.1% by mass or less, and further may not contain water. The content of the organic solvent in the non-aqueous inkjet ink composition is preferably 50% by mass or more, more preferably 70 to 98% by mass.

[0016] In the present invention, "inkjet ink composition" refers to an ink composition used in the inkjet method. The inkjet method is a recording method in which droplets such as ink are ejected from the nozzles of an inkjet head such as an inkjet recording apparatus and applied to a recording medium. In the following description, "inkjet ink composition" is also simply referred to as "ink composition" or "ink".

[0017] 1.1 Lustrous Pigment The non-aqueous inkjet ink composition according to this embodiment contains a luminous pigment. The luminous pigment has the function of imparting luminosity to the pattern formed when it adheres to the recording medium.

[0018] 1.1.1 Pigments The lustrous pigment is not particularly limited, but examples include metallic pigments and pearl pigments. The lustrous pigment may be used alone or in combination of two or more types.

[0019] Examples of metallic pigments include particles of aluminum, silver, gold, platinum, nickel, chromium, tin, zinc, indium, titanium, copper, alloys thereof, and mixtures thereof.

[0020] Pearl pigments are not particularly limited, but examples include titanium dioxide-coated mica, fish scale foil, and bismuth acid chloride, which are pigments that have a pearly or interference luster.

[0021] The shape of the lustrous pigment is not particularly limited, but examples include flat, spherical, spindle-shaped, and needle-shaped. Among these, a flat shape is preferred. Because the lustrous pigment is flat, it can be arranged on the recording medium to which the ink composition is attached so that the main surface conforms to the surface shape of the recording medium, and the gloss and other properties inherent to the lustrous pigment can be expressed more effectively.

[0022] In this embodiment, "flat" refers to a shape in which the area observed from a predetermined angle (viewed from above) is larger than the area observed from an angle perpendicular to the direction of observation. For the shape of a single luminous pigment, the maximum projected area S1 [μm²] 2 ] and the orthogonal maximum area S0[μm 2The ratio (S1 / S0) to ] is preferably 2.0 or more, more preferably 5.0 or more, and even more preferably 8.0 or more. The maximum projected area is the area when viewed from a plane, observed from the direction in which the projected area is maximized. The maximum orthogonal area is the area when viewed from a plane, observed from the direction in which the area is maximized among the directions orthogonal to the observation direction of the maximum projected area. For example, this value can be obtained by observing any 10 particles and using the average value calculated for these particles.

[0023] The glossy pigment in this embodiment preferably contains aluminum. Using aluminum results in excellent glossiness of the printed image obtained from the ink composition, as well as cost-effectiveness of raw materials. The glossy pigment only needs to contain at least aluminum; it may further contain other metals.

[0024] The lustrous pigment of this embodiment preferably contains metal particles. The metal particles only need to be composed of metal or a metal alloy (hereinafter also simply referred to as "metal") in a region including the vicinity of the surface. The metal particles may, for example, be composed entirely of metal, or they may consist of a core made of a non-metallic material and a coating made of metal covering the core. Preferably, the metal particles are the metal pigment described above.

[0025] The metal particles of the lustrous pigment may be manufactured by any method. Preferably, the metal particles are obtained by forming a metal film on one side of a sheet-like substrate using a vapor deposition method, and then peeling and pulverizing the metal film from the sheet-like substrate. Instead of vapor deposition, ion plating or sputtering may be used. This method yields flat metal particles, which allows the inherent luster and other properties of the metal particles to be expressed more effectively.

[0026] The sheet-like substrate is not particularly limited, but for example, a plastic film such as polyethylene terephthalate can be used. Furthermore, a release agent such as silicone oil may be applied to the film-forming surface of the sheet-like substrate in advance to improve release properties, or a release resin layer may be formed. The resin used for the release resin layer is not particularly limited, but examples include polyvinyl alcohol, polyvinyl butyral, polyethylene glycol, polyacrylic acid, polyacrylamide, cellulose derivatives such as cellulose acetate butyrate, and modified nylon resins. Release and pulverization are performed, for example, by irradiating the metal film with ultrasound in a non-aqueous medium, or by applying external force by stirring with a homogenizer or the like.

[0027] The non-aqueous medium used for peeling and grinding is not particularly limited, but examples include alcohol solvents, hydrocarbon solvents, and ether solvents. Among these, ether solvents are preferred. The ether solvent is not particularly limited, but examples include ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol methyl ethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol n-butyl ether, tripropylene glycol dimethyl ether, triethylene glycol diethyl ether, propylene glycol monomethyl ether acetate, 1,2-dimethoxyethane, bis(2-methoxyethyl) ether, and p-dioxane. Among these, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and diethylene glycol methyl ethyl ether are preferred, and diethylene glycol diethyl ether is more preferred.

[0028] 1.1.2 Surface treatment agents The lustrous pigment is preferably a metal particle that has been surface-treated with a surface treatment agent. By surface-treating with a surface treatment agent, the reaction of the metal particles with water can be effectively suppressed, and a lustrous pigment with excellent dispersibility can be obtained. It is presumed that in a lustrous pigment surface-treated with a surface treatment agent, the phosphorus-containing acid groups of the surface treatment agent are chemically bonded to the surface of the metal particles. In this case, the surface treatment agent itself is not necessarily bonded to the surface of the metal particles by hydrogen bonds or intermolecular forces, but may be a metal particle having residues of the surface treatment agent. That is, in a lustrous pigment surface-treated with a surface treatment agent, it is thought that the OH groups that may be present on the surface of the metal particles react with the phosphorus-containing acid groups of the surface treatment agent, resulting in a covalent bond between the metal particles and the surface treatment agent. Alternatively, the surface treatment agent may adhere to the surface of the metal particles by physical adsorption, etc. Thus, it is thought that the surface treatment agent adheres to the metal particles by bonding or physical adsorption, etc.

[0029] The surface treatment agent is not particularly limited, but examples include fluorine-based compounds and alkyl phosphates. Among these, it is preferable that the lustrous pigment is surface-treated with alkyl phosphate. Alkyl phosphate is easily applied uniformly to the surface of metal particles and can form a stable and dense film. This tends to improve the dispersion stability and gloss of the lustrous pigment.

[0030] Fluorine compounds are not particularly limited, but examples include fluorine-phosphonic acids, fluorine-carboxylic acids, fluorine-sulfonic acids, fluorine-silanes, and salts thereof.

[0031] The alkyl phosphate ester preferably includes at least one selected from, for example, the compounds represented by formula (3) and the compounds represented by formula (4). (RO-)P(O)(OH)2...Formula (3) (RO-)2P(O)(OH) ···Formula (4) (In the formula, R is independently a hydrocarbon group having 8 or more carbon atoms.)

[0032] The compound represented by formula (3) above (mono-form) is a compound in which one of the three hydroxyl groups of phosphoric acid is esterified with an R group. Because such mono-forms have low steric hindrance, they are easily surface-treated uniformly on the surface of metal particles, and can be used to produce particularly excellent dispersion stability and gloss of lustrous pigments. The compound represented by formula (4) above (di-form) is a compound in which two of the three hydroxyl groups of phosphoric acid are esterified with R groups. Due to its high steric hindrance, such di-forms make it difficult for water to approach the surface of lustrous pigments, and can be used to produce particularly excellent water resistance.

[0033] In formulas (3) and (4) above, R is a hydrocarbon group having a carbon skeleton with 8 or more carbon atoms, which is a hydrocarbon group having a skeleton in which 8 or more carbon atoms are bonded in a continuous chain. In formulas (3) and (4) above, one of the carbon atoms of the carbon skeleton of R having 8 or more carbon atoms is directly bonded to the oxygen atom of O in (RO-), and this oxygen atom is directly bonded to the phosphorus atom of P. Therefore, it is hypothesized that when the surface treatment agent reacts with the metal particles at the hydroxyl group portion bonded to the phosphorus atom of the surface treatment agent, thereby modifying the surface of the metal particles, R can be located relatively close to the metal particles, resulting in excellent dispersion stability of the lustrous pigment. Furthermore, we hypothesize that the relatively long-chain hydrocarbon group R provides excellent dispersion stability to the lustrous pigment.

[0034] Hydrocarbon groups having a carbon skeleton with eight or more carbon atoms include saturated hydrocarbon groups that do not have double or triplicate bonds between carbon atoms, and unsaturated hydrocarbon groups that have double or triplicate bonds between carbon atoms. The hydrocarbon group R may be an aromatic hydrocarbon group having an aromatic ring structure in its carbon skeleton, or a linear or cyclic aliphatic hydrocarbon group. Linear aliphatic hydrocarbon groups are particularly preferred because they offer superior dispersion stability. Linear aliphatic hydrocarbon groups may be branched or linear, but linear types are preferred because they offer superior dispersion stability, discharge stability, and gloss. In this case, for example, a large number of alkyl phosphate esters can be used to modify the surface of metal particles, which is expected to produce a sufficient effect.

[0035] Since R is a hydrocarbon group, it has a bond between a carbon atom and a hydrogen atom. If R has no substituents, R is a hydrocarbon group consisting of a carbon atom and a hydrogen atom. For example, if R is a chain-like aliphatic hydrocarbon group, examples include alkyl groups, alkenyl groups, and alkynyl groups. In this case, it is preferable for non-aqueous inks as it offers superior dispersion stability.

[0036] 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 one bond between the carbon atoms and hydrogen atoms. Therefore, R may have some of the hydrogen atoms that the hydrocarbon group can have substituted with substituents, and it is sufficient that it has one or more unsubstituted hydrogen atoms. Examples of substituents include carboxyl groups, hydroxyl groups, amino groups, oxyalkylene-containing groups, and halogen groups such as fluoro groups. In particular, substitution with fluoro groups is preferable from the viewpoint of water resistance and gloss, as it can impart high hydrophobicity to the lustrous pigment. Note that an oxyalkylene-containing group is a group having an oxyalkylene structure, and the oxyalkylene structure is also called an alkylene oxide structure. When some of the hydrogen atoms that the hydrocarbon group R may have are substituted with substituents, the number of substituents is preferably 50% or less, and more preferably 10% or less, of the number of hydrogen atoms in the hydrocarbon group when R is unsubstituted. Furthermore, the number of substituents is preferably 5 or less, and particularly preferably 3 or less. Even more preferably 2 or less, and more preferably 1 or less. The number of substituents is 0 or more, and the lower limit of the number of substituents when substituted is 1 or more. It is preferable that the substituents are located on the carbon atom furthest from the phosphorus atom in the formula, as this tends to result in better dispersion stability.

[0037] The compounds represented by formulas (3) and (4) above preferably have a hydrocarbon group with 10 or more carbon atoms as R. More preferably, R has a hydrocarbon group with 12 to 30 carbon atoms. Furthermore, the number of carbon atoms in the hydrocarbon group R is more preferably 12 to 25, even more preferably 12 to 23, even more preferably 14 to 22, particularly preferably 15 to 20, and most particularly preferably 17 to 20. When the number of carbon atoms in the hydrocarbon group R is particularly 15 to 20, preferably within the above range, the compounds tend to have superior water resistance and gloss.

[0038] In addition, R in formulas (3) and (4) above is preferably a hydrocarbon group with the same number of carbon atoms, and it is more preferable that R is the same hydrocarbon group. When R is like this, it is presumed that the alkyl phosphate adheres uniformly to the surface of the metal particles, and it tends to be possible to achieve a good balance between water resistance and gloss.

[0039] Furthermore, R in formulas (3) and (4) above is preferably an alkyl group, an alkenyl group, or an alkynyl group, and is more preferably a carbon skeleton having 10 or more carbon atoms. In this case, it is preferable that the carbon skeleton has 10 to 30 carbon atoms. Moreover, the carbon skeleton preferably has 10 to 25 carbon atoms, more preferably 12 to 23 carbon atoms, even more preferably 14 to 21 carbon atoms, and particularly preferably 16 to 19 carbon atoms. When R is an alkyl group, an alkenyl group, or an alkynyl group, and the number of carbon atoms is within the above range, the dispersion stability and gloss tend to be superior.

[0040] Specific examples of the compound (mono-form) represented by formula (3) above include monooctyl phosphate, monolauryl phosphate, monoisotridecyl phosphate, and monostearyl phosphate, and it is preferable that one or more of these be selected. More preferably, it is one or more selected from monoisotridecyl phosphate and monostearyl phosphate, and even more preferably monostearyl phosphate.

[0041] Specific examples of the compound (di-isomer) represented by the above formula (4) include dioctyl phosphate, dilauryl phosphate, diisotridecyl phosphate, and distearyl phosphate, and it is preferable that one or more are selected from these. More preferably, it is one or more selected from diisotridecyl phosphate and distearyl phosphate, and it is even more preferable that it is distearyl phosphate.

[0042] Surface treatment of metal particles with a surface treatment agent may be carried out, for example, by including the surface treatment agent in the liquid when forming metal particles by crushing a metal film formed by vapor deposition in a liquid.

[0043] The content of the surface treatment agent is preferably 1 to 100% by mass, more preferably 1 to 70% by mass, even more preferably 1 to 50% by mass, even more preferably 2 to 40% by mass, particularly preferably 4 to 30% by mass, even more preferably 6 to 20% by mass, and especially preferably 8 to 15% by mass, based on 100% by mass of the total mass of the metal particles.

[0044] When surface treatment is performed with the compound represented by formula (3) above as an alkyl phosphate, the content is preferably 0.5 to 90% by mass, more preferably 0.5 to 70% by mass, even more preferably 1 to 50% by mass, even more preferably 2 to 30% by mass, particularly preferably 3 to 20% by mass, and most particularly preferably 4 to 15% by mass, based on 100% by mass of the total mass of the metal particles. When the content of the compound represented by formula (3) above is within the above range based on 100% by mass of the total mass of the metal particles, the dispersion stability and gloss of the lustrous pigment tend to be improved.

[0045] When surface treatment is performed with the compound represented by formula (4) above as an alkyl phosphate, the content is preferably 0.05 to 30% by mass, more preferably 0.1 to 25% by mass, even more preferably 1 to 20% by mass, even more preferably 2 to 15% by mass, and particularly preferably 3 to 10% by mass, based on 100% by mass of the total mass of the metal particles. When the content of the compound represented by formula (4) above is within the above range based on 100% by mass of the total mass of the metal particles, the water resistance tends to be superior.

[0046] 1.1.3 Physical properties etc. The glossy pigment preferably has a volume-average particle diameter (D50) of 0.5 μm or less and an average thickness of 30 nm or less. Furthermore, the aspect ratio (volume-average particle diameter (D50) / average thickness) of the glossy pigment is preferably 15 to 60, more preferably 20 to 50, and even more preferably 30 to 40. Such glossy pigments tend to have poor leafing properties and are prone to reduced dispersibility, resulting in poor gloss. However, according to the non-aqueous inkjet ink composition of this embodiment, good gloss can be obtained even with such glossy pigments.

[0047] The lower limit of the volume average particle size (D50) of the lustrous pigment is not particularly limited, but is preferably 0.10 μm or more, more preferably 0.20 μm or more, even more preferably 0.25 μm or more, and particularly preferably 0.30 μm or more. The upper limit of the volume average particle size (D50) of the lustrous pigment is not particularly limited, but may be 5.00 μm or less, may be 3.00 μm or less, may be 1.00 μm or less, may be 0.70 μm or less, and is preferably 0.55 μm or less.

[0048] In this invention, "volume-average particle diameter (D50)" refers to the median diameter of the volume distribution of a lustrous pigment dispersion measured using laser diffraction and scattering methods. When multiple measurement results are expressed as the cumulative abundance ratio for each size, D50 is the particle size that represents exactly 50% of the median value in the cumulative distribution. If the lustrous pigment is flat, the volume-average particle diameter shall be determined based on the shape and size of the lustrous pigment when converted to a spherical shape.

[0049] The lower limit of the average thickness of the lustrous pigment is not particularly limited, but is preferably 5 nm or more, more preferably 7 nm or more, even more preferably 9 nm or more, particularly preferably 11 nm or more, and most particularly preferably 13 nm or more. The upper limit of the average thickness of the lustrous pigment is not particularly limited, but may be 60 nm or less, may be 40 nm or less, preferably 25 nm or less, more preferably 23 nm or less, even more preferably 21 nm or less, particularly preferably 19 nm or less, and most particularly preferably 17 nm or less. The average thickness of the lustrous pigment is particularly preferably 15 nm.

[0050] The average thickness of a lustrous pigment can be measured using an atomic force microscope (AFM). While not limited to AFM, it can be measured using, for example, an atomic force microscopy method with NanoNaviE-Sweep (manufactured by SII Nanotechnology). For example, measurements can be taken on any 50 lustrous pigments and the average value can be used. That is, the average thickness is preferably the arithmetic mean thickness.

[0051] The lower limit of the content of the lustrous pigment is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, even more preferably 0.5% by mass or more, particularly preferably 0.7% by mass or more, and most particularly preferably 0.9% by mass or more, relative to the total mass of the ink composition. The upper limit of the content of the lustrous pigment is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 2% by mass or less, particularly preferably 1.7% by mass or less, and most particularly preferably 1.4% by mass or less, relative to the total mass of the ink composition. When the content of the lustrous pigment is within the above range, it tends to be possible to improve the storage stability and water resistance of the ink composition, while also making the glossiness and scratch resistance of the colored part formed using the ink composition particularly excellent.

[0052] 1.2 Glycol monoether The non-aqueous inkjet ink composition according to this embodiment contains glycol monoether A and glycol monoether B, which are represented by the following formula (1) and have different flash points. R1-(O-R2) n -OH...Formula (1) (In formula (1), R1 is an alkyl group or phenyl group having 1 to 8 carbon atoms, R2 is an alkylene group having 1 to 5 carbon atoms, and n is an integer from 1 to 4.)

[0053] In formula (1) above, R1 and R2 may be branched or linear. Examples of R1 include a methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, sec-butyl group, tert-butyl group, etc. Examples of R2 include a methylene group, ethylene group (dimethylene), propylene group (trimethylene or methylethylene), butylene group, etc.

[0054] Here, "flash point" is defined in JIS K2265 as "the temperature at which, under specified conditions, when an ignition source is brought close to the sample vapor, the sample vapor emits a flash of light and burns instantaneously, and the flame propagates across the liquid surface, with the lowest temperature of the sample corrected to 101.3 kPa." In other words, the flash point is determined by the volatility of the sample and the flammability of the gas after volatilization, taking into account the vapor pressure at lower temperatures. In contrast, the standard boiling point is the boiling point at a pressure of 1 atm, taking into account the vapor pressure at higher temperatures. In this study, experiments confirmed that the flash point has a higher correlation with the drying rate of liquids than the standard boiling point. This is because the relationship (slope) between the vapor pressure at low temperatures and the vapor pressure at high temperatures differs depending on the compound, and since the temperature in the printing process is on the lower side, around 23-40°C, it is presumed that the flash point, which is closer to the printing process temperature, has a higher correlation with the drying rate.

[0055] Furthermore, if the flash point measured by a Tagh closed-type flash point tester is above 80°C, it is preferable to measure it using a Cleveland open-type flash point tester. If the flash point measured by a Tagh closed-type flash point tester is 80°C or lower and the kinematic viscosity of the solvent at that flash point is less than 10 cSt, it is preferable to measure it using a Tagh closed-type flash point tester. If the kinematic viscosity of the solvent at that flash point is 10 cSt or higher, it is preferable to measure it using a Seta closed-type flash point tester.

[0056] 1.2.1 Glycol monoether A The glycol monoether A contained in the non-aqueous inkjet ink composition according to this embodiment has a flash point of 85°C or lower and is preferably represented by the following formula (1)'. R1-(O-R2) n -OH...Formula (1)' (In formula (1)', R1 is an alkyl group having 1 to 4 carbon atoms, R2 is an alkylene group having 1 to 5 carbon atoms, and n is an integer from 1 to 4.)

[0057] The glycol monoether A described above effectively improves the drying properties of the ink while suppressing effects on recording media such as swelling, and provides appropriate adhesion.

[0058] The lower limit of the flash point of the glycol monoether A is not particularly limited, but for example, it is preferably 30°C or higher, more preferably 50°C or higher, even more preferably 60°C or higher, and particularly preferably 70°C or higher. The upper limit of the flash point of the glycol monoether A is preferably 83°C or lower, and even more preferably 80°C or lower. If the flash point is within the above range, better gloss may be obtained.

[0059] In the glycol monoether A described above, R2 in formula (1)' is preferably an alkylene group having 2 to 3 carbon atoms, and more preferably an alkylene group having 3 carbon atoms. When such a glycol monoether A is used, the effects of swelling on the recording medium can be further reduced, and better gloss tends to be obtained. Furthermore, the dispersibility of the lustrous pigment can also be improved.

[0060] In the glycol monoether A described above, R1 in formula (1)' is preferably an alkyl group having 1 to 2 carbon atoms, and more preferably an alkyl group having 1 carbon atom. Using such a glycol monoether A may result in better gloss and reduced unevenness.

[0061] The glycol monoether A described above preferably has n as 1 to 3 in formula (1)', more preferably as 1 to 2, and even more preferably as 2. Using such a glycol monoether A may result in better gloss and reduced unevenness.

[0062] The specific compounds of glycol monoether A mentioned above are not particularly limited, but examples include methylene glycol monobutyl ether (BMG, 63°C), ethylene glycol monoisopropyl ether (44°C), ethylene glycol monoethyl ether (43°C), ethylene glycol monobutyl ether (60°C), ethylene glycol monomethyl ether (41°C), propylene glycol monobutyl ether (BPG, 61.5°C), diethylene glycol monoethyl ether (86°C), diethylene glycol monobutyl ether (78°C), diethylene glycol monomethyl ether (93°C), dipropylene glycol monomethyl ether (MFDG, 79°C), propylene glycol monoethyl ether (38.5°C), propylene glycol monomethyl ether (36°C), and 3-methoxy-3-methylbutanol (MMB, 68°C) (the values ​​in parentheses indicate the flash point). Among these, the glycol monoether A is preferably one or more selected from methylene glycol monobutyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, and 3-methoxy-3-methylbutanol, and is particularly preferably dipropylene glycol monomethyl ether. With such a glycol monoether A, the drying properties of the ink tend to be improved, while the effects on the recording medium such as swelling are further suppressed, and a more appropriate level of adhesion can be obtained.

[0063] The content of glycol monoether A is preferably 15 to 55% by mass, more preferably 15 to 40% by mass, even more preferably 15 to 30% by mass, and particularly preferably 15 to 25% by mass, based on the total amount of the ink composition. When the content of glycol monoether A is within the above range, better gloss and reduction of unevenness tend to be obtained.

[0064] 1.2.2 Glycol monoether B The glycol monoether B contained in the non-aqueous inkjet ink composition according to this embodiment has a flash point of 95°C or higher and is preferably represented by the following formula (1)''. R1-(O-R2) n -OH...Formula (1)'' (In formula (1)'', R1 is an alkyl group or phenyl group having 1 to 8 carbon atoms, R2 is an alkylene group having 1 to 4 carbon atoms, and n is an integer from 1 to 4.)

[0065] The glycol monoether B described above is a solvent that dries relatively slowly, which helps to effectively reduce the drying time of the ink and ensures sufficient time for the pigment to leaf out.

[0066] The upper limit of the flash point of glycol monoether B is not particularly limited, but for example, it is preferably 200°C or lower, more preferably 180°C or lower, even more preferably 170°C or lower, and particularly preferably 160°C or lower. The lower limit of the flash point of glycol monoether A is preferably 110°C or higher, more preferably 120°C or higher, even more preferably 130°C or higher, particularly preferably 140°C or higher, and most particularly preferably 150°C or higher. If the flash point is within the above range, better gloss may be obtained.

[0067] In the glycol monoether B described above, R1 in formula (1)'' is preferably an alkyl group having 1 to 2 carbon atoms, and more preferably an alkyl group having 1 carbon atom. Using such a glycol monoether B may result in better gloss and reduced unevenness.

[0068] In the glycol monoether B described above, R2 in formula (1)'' is preferably an alkylene group having 2 to 3 carbon atoms, and more preferably an alkylene group having 2 carbon atoms. Using such a glycol monoether B may result in better gloss and reduced unevenness.

[0069] The glycol monoether B described above preferably has n as 2 to 4 in formula (1)'', more preferably 3 to 4, and even more preferably 4. Using such a glycol monoether B may result in better gloss and reduced unevenness.

[0070] The specific compounds of glycol monoether B mentioned above are not particularly limited, but examples include diethylene glycol ethylhexyl ether (EHDG, 136.7°C), dipropylene glycol monobutyl ether (BFDG, 100°C), dipropylene glycol phenyl ether (PhDG, 140.9°C), tetraethylene glycol monomethyl ether (MtetG, 126°C), tetraethylene glycol monobutyl ether (BTGH, 156°C), triethylene glycol monomethyl ether (MTG, 95.3°C), triethylene glycol monoethyl ether (135°C), triethylene glycol monobutyl ether (143°C), and tripropylene glycol monomethyl ether (MFTG, 117.6°C) (the values ​​in parentheses indicate the flash point). Among these, the glycol monoether B is preferably one or more selected from diethylene glycol ethylhexyl ether, dipropylene glycol phenyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monobutyl ether, triethylene glycol monomethyl ether, and tripropylene glycol monomethyl ether, and is particularly preferably tetraethylene glycol monobutyl ether. When the glycol monoether B is tetraethylene glycol monobutyl ether, the leafing properties are better and the gloss can be further improved. This is because tetraethylene glycol monobutyl ether has relatively high polarity and can more preferably leaf in interaction with the surface of a luminous pigment with low surface free energy. In addition, tetraethylene glycol monobutyl ether has little effect on the recording medium, is less likely to swell the recording medium, and can suppress the decrease in gloss due to surface irregularities.

[0071] The content of glycol monoether B is preferably 5 to 15% by mass, more preferably 8 to 13% by mass, and even more preferably 9 to 12% by mass, based on the total amount of the ink composition. When the content of glycol monoether B is within the above range, better gloss and reduction of unevenness tend to be obtained.

[0072] 1.2.3 Content In the non-aqueous inkjet ink composition according to this embodiment, the total content of glycol monoether A and glycol monoether B is 20 to 60% by mass of the total amount of the ink composition, and the content of glycol monoether A is greater than the content of glycol monoether B.

[0073] By incorporating glycol monoether A and glycol monoether B in specific amounts as described above, it is possible to maintain appropriate adhesion while reducing unevenness caused by swelling of the recording medium, and to optimize the ink drying speed, thereby achieving high gloss and good reduction of unevenness.

[0074] The total content of glycol monoether A and glycol monoether B is preferably 20 to 55% by mass, more preferably 20 to 50% by mass, even more preferably 20 to 45% by mass, even more preferably 20 to 40% by mass, particularly preferably 23 to 40% by mass, and most particularly preferably 25 to 35% by mass, based on the total amount of the ink composition. When the total content is within the above range, higher gloss and good reduction of unevenness tend to be obtained.

[0075] The content of glycol monoether A relative to the total amount of the ink composition is preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 3% by mass or more, even more preferably 5% by mass or more, particularly preferably 7% by mass or more, and most particularly preferably 9% by mass or more. There is no particular upper limit, but for example, the content of glycol monoether A is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, even more preferably 25% by mass or less, particularly preferably 20% by mass or less, and most particularly preferably 15% by mass or less, compared to the content of glycol monoether B. With such content relationships, higher gloss and good reduction of unevenness tend to be obtained.

[0076] The mass ratio of glycol monoether A to glycol monoether B (A / B) is preferably 1.1 or more, more preferably 1.3 or more, even more preferably 1.5 or more, and particularly preferably 1.8 or more. There is no particular upper limit, but for example, it is preferably 6.0 or less, more preferably 5.0 or less, even more preferably 4.0 or less, particularly preferably 3.0 or less, and most particularly preferably 2.5 or less. When such a mass ratio (A / B) is within the above range, higher gloss and good reduction of unevenness tend to be obtained.

[0077] 1.3 Other Solvents 1.3.1 Glycol diether The non-aqueous inkjet ink composition according to this embodiment preferably further contains a glycol diether represented by the following formula (2). R3O-(R4O) m -R5...Formula (2) (In formula (2), R3 and R5 are each independently alkyl groups having 1 to 4 carbon atoms, R4 is an alkylene group having 2 to 3 carbon atoms, and m is an integer from 1 to 4.)

[0078] In formula (2) above, R3, R4, and R5 may be branched or linear. Examples of R3 and R5 include methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, sec-butyl group, and tert-butyl group. Examples of R4 include ethylene group (dimethylene) and propylene group (trimethylene or methylethylene).

[0079] The glycol diether described above has moderate drying properties and minimal impact on recording media, and therefore, including it tends to result in higher gloss and better reduction of unevenness. Furthermore, the glycol diether is advantageous in that it facilitates intermittent printing stability in ink ejection by inkjet methods and has low odor.

[0080] The flash point of the glycol diether described above is not particularly limited, but is preferably 50°C or higher, more preferably 60°C or higher, even more preferably 65°C or higher, and particularly preferably 70°C or higher.

[0081] The specific compounds of the glycol diether mentioned above are not particularly limited, but examples include glycol diethyl ether (35°C), ethylene glycol dimethyl ether (-6°C), diethylene glycol methyl ethyl ether (63°C), diethylene glycol dimethyl ether (56°C), diethylene glycol diethyl ether (DEDG, 71°C), dipropylene glycol dimethyl ether (65°C), and propylene glycol dimethyl ether (6.5°C) (the values ​​in parentheses indicate the flash point). The glycol diether may be used alone or in combination of two or more. Among these, diethylene glycol diethyl ether is preferred as the glycol diether represented by formula (2) above.

[0082] The content of the glycol diether represented by formula (2) above is preferably 35 to 75% by mass, more preferably 45 to 70% by mass, even more preferably 50 to 70% by mass, and particularly preferably 55 to 70% by mass, based on the total amount of the ink composition. When the content of the glycol diether represented by formula (2) above is within the above range, better gloss and reduction of unevenness tend to be obtained.

[0083] 1.3.2 Cyclic esters The non-aqueous inkjet ink composition according to this embodiment preferably further contains a cyclic ester. Because cyclic esters have a high affinity for the surface of the recording medium (e.g., a vinyl chloride resin), the adhesion of the ink to the recording medium can be further improved. This makes it possible to obtain images with superior friction fastness. On the other hand, when a cyclic ester is included, swelling tends to occur, causing irregularities on the surface of the recording medium and reducing gloss. However, according to the non-aqueous inkjet ink composition according to this embodiment, even when a cyclic ester is included, it is possible to reduce irregularities caused by swelling of the recording medium and maintain good gloss.

[0084] A cyclic ester is a compound having a structure in which a hydroxyl group and a carboxyl group are dehydrated and condensed within the molecule. Cyclic esters have a heterocycle containing two or more carbon atoms and one oxygen atom, with a carbonyl group positioned adjacent to the oxygen atom forming the heterocycle, and are collectively called lactones.

[0085] Examples of cyclic esters include γ-butyrolactone (GBL), γ-valerolactone, γ-hexalactone, γ-heptalactone, γ-octaractone, γ-nonalactone, γ-decalactone, γ-undecalactone, δ-valerolactone, δ-hexalactone, δ-heptalactone, δ-octaractone, δ-nonalactone, δ-decalactone, δ-undecalactone, ε-caprolactam, and the like. There are no particular restrictions on the number of ring members in the heterocycle of the cyclic ester, and furthermore, any side chain may be attached to the ring members of the heterocycle, for example. The cyclic ester may be used alone or in a mixture of two or more types.

[0086] Of the cyclic esters exemplified above, cyclic esters with 3 to 7 membered rings are preferred, and cyclic esters with 5 or 6 membered rings are more preferred, and in either case, it is even more preferable that they do not have side chains. Specific examples of such cyclic esters include γ-butyrolactone and δ-valerolactone.

[0087] When a cyclic ester is included, the cyclic ester content is preferably 1 to 15% by mass, more preferably 2 to 10% by mass, and even more preferably 3 to 8% by mass, relative to the total amount of the ink composition. When the cyclic ester content is within the above range, good gloss tends to be obtained while maintaining appropriate adhesion.

[0088] 1.3.3 Others The non-aqueous inkjet ink composition according to this embodiment may contain solvents other than those mentioned above, such as alcohols, ketones, carboxylic acid esters, ethers, alkanediols, polyhydric alcohols, and amines.

[0089] Examples of alcohols include methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, isopropyl alcohol, and fluorinated alcohol.

[0090] Examples of ketones include acetone, methyl ethyl ketone, and cyclohexanone.

[0091] Examples of carboxylic acid esters include methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, and ethyl propionate.

[0092] Examples of ethers include diethyl ether, dipropyl ether, tetrahydrofuran, and dioxane.

[0093] Examples of 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-butylene glycol, 1,4-butanediol, 2,3-butanediol, 1,2-pentanediol, 1,5-pentanediol, and 2,4-pentanediol. Examples include benzodiol, 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, and 2-methyl-2-propyl-1,3-propanediol.

[0094] Examples of polyhydric alcohols include diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, butylene glycol, 1,2,6-hexanetriol, thioglycol, hexylene glycol, glycerin, trimethylolethane, and trimethylolpropane.

[0095] Examples of amines include hydroxylamines such as triethanolamine, trippropanolamine, tributanolamine, N,N-dimethyl-2-aminoethanol, and N,N-diethyl-2-aminoethanol.

[0096] Furthermore, examples of solvents include higher fatty acid esters such as methyl laurate, isopropyl hexadecanate (isopropyl palmitate), isopropyl myristate, methyl oleate, and ethyl oleate; dibasic acid diesters obtained by diesterifying a dicarboxylic acid of an aliphatic hydrocarbon having 2 to 8 carbon atoms (excluding the carbon atoms of the carboxyl group) with an alkyl group having 1 to 5 carbon atoms; and alkylamides (such as N,N-dimethyldecaneamide) obtained by amidating a monocarboxylic acid of an aliphatic hydrocarbon having 6 to 10 carbon atoms (excluding the carbon atoms of the carboxyl group) (where the substituents substituting the amide nitrogen atom are independently a hydrogen atom and an alkyl group having 1 to 4 carbon atoms).

[0097] 1.4 Resin The non-aqueous inkjet ink composition according to this embodiment preferably further contains an acrylic resin. Acrylic resins have little effect on reducing gloss. This is presumed to be because the viscosity increase when acrylic resins are dissolved in a solvent is relatively high, which improves leafing properties. Therefore, by further containing an acrylic resin, it is possible to improve abrasion resistance while maintaining high gloss.

[0098] Examples of acrylic resins include poly(meth)acrylic acid, poly(meth)acrylate, poly(meth)acrylate, poly(meth)acrylate, (meth)acrylic acid-(meth)acrylic acid ester copolymer resin, styrene-(meth)acrylic copolymer resin, ethylene-(meth)acrylic acid copolymer resin, ethylene alkyl (meth)acrylate resin, and ethylene-(meth)acrylic acid ester copolymer resin.

[0099] In this specification, "(meth)acrylic" refers to acrylic or methacrylic, and "(meth)acrylate" refers to acrylate or methacrylate.

[0100] The acrylic resins mentioned above may be commercially available products, such as Acrypet MF (product name, manufactured by Mitsubishi Rayon Co., Ltd., acrylic resin), Sumipex LG (product name, manufactured by Sumitomo Chemical Co., Ltd., acrylic resin), Paraloid B series such as Paraloid B60 (product name, manufactured by Dow Chemical Co., Ltd., acrylic resin), and Parapet G-1000P (product name, manufactured by Kuraray Co., Ltd., acrylic resin).

[0101] When an acrylic resin is included, the acrylic resin content is preferably 0.05 to 1.00% by mass, more preferably 0.10 to 0.70% by mass, even more preferably 0.15 to 0.40% by mass, and particularly preferably 0.20 to 0.30% by mass, based on the total mass of the ink composition. When the acrylic resin content is within the above range, it tends to be possible to further improve abrasion resistance while maintaining high gloss.

[0102] The non-aqueous inkjet ink composition according to this embodiment may contain resins other than acrylic resins. Examples of such resins include vinyl chloride resins, aliphatic polyesters, aromatic polyesters, polyurethanes, epoxy resins, polyvinyl acetate, ethylene-vinyl acetate copolymer resins, polycarbonates, polyvinyl butyral, polyvinyl alcohol, phenoxy resins, ethylcellulose resins, cellulose acetate propionate resins, cellulose acetate butyrate, nitrocellulose resins, polystyrene, vinyltoluene-α-methylstyrene copolymer resins, polyamides, polyimides, polysulfone resins, petroleum resins, chlorinated polypropylene, polyolefins, terpene resins, rosin-modified phenolic resins, various synthetic rubbers such as NBR, SBR, and MBR, and their modified forms. These resins may be used individually or in mixtures of two or more.

[0103] 1.5 Surface modifier The non-aqueous inkjet ink composition according to this embodiment preferably further contains a surface modifier. The surface modifier has the function of improving the lubricity of the printed surface and improving friction fastness. The surface modifier is also called a slip agent.

[0104] As a surface modifier, a silicone-based surfactant is preferred, and a modified silicone compound such as polyester-modified silicone or polyether-modified silicone is more preferred. Examples of polyester-modified silicones include BYK-347, 348, BYK-UV3500, 3510, and 3530 (all manufactured by BYK Additives & Instruments), and examples of polyether-modified silicones include BYK-333 and 3570 (manufactured by BYK Additives & Instruments).

[0105] When a surface modifier is included, the content of the surface modifier is preferably 0.01 to 1.00% by mass, more preferably 0.01 to 0.50% by mass, even more preferably 0.01 to 0.20% by mass, even more preferably 0.02 to 0.10% by mass, particularly preferably 0.03 to 0.08% by mass, and most particularly preferably 0.03 to 0.07% by mass, based on the total mass of the ink composition. When the content of the surface modifier is within the above range, friction fastness tends to be improved.

[0106] 1.6 Dispersant The non-aqueous inkjet ink composition according to this embodiment may further contain a dispersant for dispersing the luminous pigment. The dispersant is not particularly limited, but examples include anionic dispersants, nonionic dispersants, and polymeric dispersants.

[0107] Examples of anionic dispersants are not particularly limited, but include formalin condensates of aromatic sulfonic acids, formalin condensates of β-naphthalene sulfonic acids, formalin condensates of alkylnaphthalene sulfonic acids, and formalin condensates of creosote oil sulfonic acids.

[0108] The above-mentioned aromatic sulfonic acid is not particularly limited, but examples include creosote oil sulfonic acid, cresol sulfonic acid, phenol sulfonic acid, alkylnaphthalene sulfonic acid such as β-naphthol sulfonic acid, methylnaphthalene sulfonic acid, and butylnaphthalene sulfonic acid, a mixture of β-naphthalene sulfonic acid and β-naphthol sulfonic acid, a mixture of cresol sulfonic acid and 2-naphthol-6-sulfonic acid, lignin sulfonic acid, and the like.

[0109] Nonionic dispersants are not particularly limited, but examples include ethylene oxide adducts of phytosterols and ethylene oxide adducts of cholestanol.

[0110] The polymer dispersant is not particularly limited, but examples include polyoxyalkyleneamine compounds, partially alkyl esters of polyacrylates, polyalkylene polyamines, polyacrylate salts, styrene-acrylic acid copolymers, vinylnaphthalene-maleic acid copolymers, and the like. Examples of commercially available polyoxyalkyleneamine compounds include JEFFAMIN M2070 (manufactured by Huntsman) and GENAMIN (M41 / 2000) (manufactured by Clariant).

[0111] 1.7 Other Ingredients The non-aqueous inkjet ink composition according to this embodiment may also contain various additives as appropriate, such as surfactants, solubilizers, viscosity modifiers, pH adjusters, antioxidants, preservatives, fungicides, corrosion inhibitors, and chelating agents for capturing metal ions that affect dispersion.

[0112] 2. Recording Method A recording method according to one embodiment of the present invention comprises a step (ink adhesion step) of ejecting the above-mentioned non-aqueous inkjet ink composition by an inkjet method and adhering it to a recording medium.

[0113] According to the recording method according to this embodiment, since the above-described non-aqueous inkjet ink composition is used, which can maintain appropriate adhesion between the recording medium and the ink, reduce unevenness due to swelling of the recording medium, and make the drying speed of the ink appropriate, it is possible to print an image with high glossiness and good reduction of unevenness.

[0114] 2.1 Ink Attachment Step The ink attachment step is a step of attaching the above-described non-aqueous inkjet ink composition to a recording medium using an inkjet method. Discharge of the ink composition by an inkjet method can be performed using a known inkjet recording apparatus. As the discharge method, a piezo method, a method of discharging ink by bubbles generated by heating the ink, or the like can be used.

[0115] (Recording Medium) The recording medium is not particularly limited, and examples thereof 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 preferable as applications of non-aqueous inks.

[0116] The absorbent recording medium is not particularly limited, and examples thereof include plain paper such as electrophotographic paper having high permeability of the ink composition, inkjet paper (inkjet dedicated paper provided with an ink absorption layer composed of silica particles or alumina particles, or an ink absorption layer composed of a hydrophilic polymer such as polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP)), and a recording medium having a support made of paper.

[0117] A recording medium with low ink absorption or non-absorption refers to a recording medium that has the property of not absorbing or hardly absorbing the ink composition. Quantitatively, a recording medium with non-absorption or low absorption of ink is a recording medium in which "the water absorption amount from the start of contact to 30 msec in the Bristow method is 10 mL / m 1 / 2 up to 2This refers to "recording media as described below." The Bristow method is the most widely used method for measuring liquid absorption in a short time and is also adopted by the Japan Paper & Pulp Technology Association (JAPAN TAPPI). Details of the test method are described in standard No. 51 "Paper and cardboard - Liquid absorbency test method - Bristow method" of the "JAPAN TAPPI Paper & Pulp Test Methods 2000 Edition." In contrast, ink-absorbing recording media refer to recording media that do not fall under the categories of ink-non-absorbing or low-absorbing.

[0118] Examples of ink-non-absorbent recording media include plastic films without an ink-absorbing layer, substrates such as paper coated with plastic, and substrates to which plastic films are bonded. Examples of plastics in this context include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, and polypropylene.

[0119] Furthermore, low-ink-absorption recording media include recording media having a coating layer on the surface for receiving ink. For example, if the substrate is paper, examples include printing paper such as art paper, coated paper, and matte paper. If the substrate is plastic film, examples include those coated with a hydrophilic polymer on the surface of polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene, etc., or those coated with silica, titanium, or other particles together with a binder.

[0120] In addition to the recording media mentioned above, non-ink-absorbing or low-absorbing recording media such as metal plates made of iron, silver, copper, aluminum, or glass can also be used.

[0121] 2.2 Other processes (Coloring ink application process) The recording method according to this embodiment may include a step of ejecting a colored ink composition containing a colorant by an inkjet method and adhering it to a recording medium (colored ink adhesion step).

[0122] The order in which the above-described ink application process and the colored ink application process are performed is not particularly limited, but it is preferable to perform the colored ink application process after the ink application process. Furthermore, the above-described non-aqueous inkjet ink composition and the colored ink composition may be applied to separate locations on the recording medium, or they may be applied to the same location on top of each other, but it is preferable to apply them to the same location on top of each other.

[0123] The colored ink composition can be made in the same way as the non-aqueous inkjet ink composition described above, except that it contains a colorant instead of a luminous pigment, in terms of the components and composition it contains.

[0124] The colored ink composition contains a colorant. Examples of colorants include pigments and dyes. Examples of pigments include inorganic pigments and organic pigments. Examples of dyes include acid dyes, reactive dyes, and direct dyes. Note that the colorant does not include the aforementioned luminous pigments.

[0125] Inorganic pigments are not particularly limited, but examples include carbon blacks such as furnace black, lamp black, acetylene black, and channel black; and white inorganic oxides such as iron oxide, titanium oxide, zinc oxide, and silica.

[0126] Examples of carbon blacks include CI (Colour Index Generic Name) Pigment Black 1, 7, and 11. Commercially available carbon blacks may also be used, such as Mitsubishi Chemical's No. 2300, No. 900, MCF88, No. 33, No. 40, No. 45, No. 52, MA7, MA8, MA100, and No. 2200B; Columbia Carbon's Raven (registered trademark) 5750, 5250, 5000, 3500, 1255, and 700; CABOT's Rega1 (registered trademark) 400R, 330R, and 660R; Mogul (registered trademark) L; and Monarch (registered trademark) 700, 800, 880, 900, 1000, 1100, 1300, and 1400; and Degussa's Color Black. Examples include FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Printex® 35, U, V, 140U, and SpecialBlack 6, 5, 4A, 4.

[0127] Examples of organic pigments include quinacridone pigments, quinacridone quinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, ancenthrone pigments, indanthrone pigments, flavanthrone pigments, perylene pigments, diketopyrrolopyrrole pigments, perinone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimimidazolone pigments, isoindolinone pigments, azomethine pigments, or azo pigments.

[0128] Specific examples of organic pigments include the following:

[0129] Examples of cyan pigments include CI Pigment Blue 1, 2, 3, 15:3, 15:4, 15:34, 16, 22, 60, etc.; CI Bat Blue 4, 60, etc. Preferably, one or more mixtures selected from the group consisting of CI Pigment Blue 15:3, 15:4, and 60 can be exemplified.

[0130] Examples of magenta pigments include CI Pigment Red 5, 7, 12, 48(Ca), 48(Mn), 57(Ca), 57:1, 112, 122, 123, 168, 184, 202, and CI Pigment Violet 19. Preferably, one or more mixtures selected from the group consisting of CI Pigment Red 122, 202, and 209, and CI Pigment Violet 19 can be exemplified.

[0131] Examples of yellow pigments include CI Pigment Yellow 1, 2, 3, 12, 13, 14C, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 119, 110, 114, 128, 129, 138, 150, 151, 154, 155, 180, 185, etc. Preferably, one or more mixtures selected from the group consisting of CI Pigment Yellow 74, 109, 110, 128, 138, 150, and 180 can be exemplified.

[0132] Other colored pigments can also be used. For example, orange pigment and green pigment can be used.

[0133] Pigments may be used individually or in combination of two or more types.

[0134] Furthermore, to improve the dispersibility of the pigment in the colored ink composition, it is preferable to surface-treat the pigment or to incorporate a dispersant.

[0135] Furthermore, the colored ink composition and the non-aqueous inkjet ink composition described above may be used together as an ink set for recording. An "ink set" refers to two or more inks used together for recording. Each ink in an ink set may be housed in a separate ink container, or it may be housed in an integrated ink container. An ink set comprises at least one (one type) of the non-aqueous inkjet ink composition described above and at least one (one type) of colored ink composition.

[0136] (Primary heating process) The recording method according to this embodiment may include a primary heating step, which is a step of heating the ink composition attached to the recording medium at an early stage.

[0137] The primary heating process is a process of heating and drying the ink adhering to the recording medium at an early stage. The primary heating process is a heating process to dry at least a portion of the liquid medium of the ink adhering to the recording medium to the extent that the flow of the ink is reduced.

[0138] The primary heating step may involve applying ink to the heated recording medium, or it may involve heating as soon as possible after the ink has been applied. It is preferable that heating of the ink droplets that have landed on the recording medium begins no later than 0.5 seconds after the droplets land.

[0139] The primary heating step is preferably performed by using an IR heater, microwave radiation, a platen heater, or blowing warm air onto the recording medium using a fan.

[0140] The heating in the primary heating step can be performed before the ink adhesion step, simultaneously with the adhesion step, or shortly after the adhesion step, and it is preferable that it be performed simultaneously. The ink adhesion step can be carried out with this heating sequence. In particular, it is preferable to heat the recording medium and then adhere the ink composition to the heated recording medium by the ink adhesion step.

[0141] When a primary heating step is included, the ink composition can be dried rapidly on the recording medium, which is preferable as it prevents ink bleeding. On the other hand, when a primary heating step is included, because the ink dries rapidly, there may not be enough time for the glossy pigment to leaf out, resulting in poor gloss, or the ejection stability may be poor due to the heat from the primary heating step. However, according to the recording method of this embodiment, by using the above-mentioned non-aqueous inkjet ink composition, excellent gloss and ejection stability can be obtained even when a primary heating step is performed, which is preferable.

[0142] In the primary heating step where the ink composition is heated, the surface temperature of the recording surface of the recording medium is preferably 30°C or higher. On the other hand, 60°C or lower is preferable. Furthermore, 35°C to 55°C is preferable, and even more preferably 40°C to 50°C. When the surface temperature of the recording medium is as described above, it is preferable for better prevention of bleeding and improved ejection stability. Note that the surface temperature of the recording medium in the primary heating step is the surface temperature of the recording medium when the ink is applied, or, if heating is performed after application, the temperature of the recording medium at the time of heating. It is also the highest temperature during recording.

[0143] (Post-heating process) The recording method according to this embodiment may include a post-heating step (secondary heating step) in which the recording medium is heated after the ink application step.

[0144] The post-heating process is a heating process that completes the recording and heats the recorded material sufficiently so that it can be used. The post-heating process is a heating process that ensures the solvent components of the ink are thoroughly dried.

[0145] The post-heating step is preferably started more than 0.5 seconds after the ink has adhered to the recording medium. For example, it is preferable to start heating a recording area of ​​the recording medium more than 0.5 seconds after the adhesion of ink to that area is completely finished.

[0146] The heating of the recording medium in the post-heating step can be carried out, for example, using an appropriate heating means. In this case, the surface temperature of the recording medium is preferably 50°C or higher, and more preferably 60°C or higher, 70°C or higher, or 75°C or higher. There is no upper limit, but 120°C or lower is preferred. Furthermore, the heating temperature is preferably below the softening point of the recording medium's substrate.

[0147] 2.3 Recording device An example of a recording device that can be suitably used in the recording method according to this embodiment will be described below with reference to the drawings.

[0148] (Outline of the device configuration) Figure 1 is a schematic cross-sectional view illustrating a recording device. As shown in Figure 1, the inkjet recording device 1 comprises a recording head 2, an IR heater 3, a platen 4, a heating element 5, a cooling fan 6, a preheater 7, and a ventilation fan 8. The recording head is mounted on a carriage (not shown) and performs a main scan in the front-back direction in the figure to adhere ink to the recording medium M. The platen 4 is also provided with a platen heater (not shown). The inkjet recording device 1 includes a control unit (not shown) that controls each part to perform recording. The recording head 2 receives ink from an ink reservoir (not shown).

[0149] (Configuration related to the inkjet head) The inkjet head, recording head 2, records onto the recording medium M by ejecting an ink composition from its nozzles. As shown in Figure 1, recording head 2 is a serial recording head that scans the recording medium M multiple times in the main scanning direction relative to the recording medium M to deposit ink onto the recording medium M. Recording head 2 is mounted on a carriage (not shown). Recording head 2 is scanned multiple times in the main scanning direction relative to the recording medium M by the operation of a carriage movement mechanism that moves the carriage in the media width direction of the recording medium M (back-to-front direction in the figure). The media width direction is the main scanning direction of recording head 2. Scanning in the main scanning direction is also called main scanning.

[0150] Here, the main scanning direction is the direction in which the carriage equipped with the recording head 2 moves. In Figure 1, this direction intersects with the sub-scanning direction, which is the transport direction of the recording medium M indicated by arrow SS. Recording is then performed on the recording medium M by repeatedly performing the main scan of the recording head 2 and the sub-scan, which is the transport of the recording medium M.

[0151] Conventional methods can be used for ejecting ink droplets from the recording head 2. For example, a method that uses the vibration of a piezoelectric element to eject droplets, that is, an ejection method that forms ink droplets by the mechanical deformation of an electrostrictive element, can be used.

[0152] (Primary heating mechanism) The inkjet recording device 1 may be equipped with a primary heating mechanism that performs a primary heating process to heat the recording medium M when ejecting ink from the recording head 2 and adhering it to the recording medium. The primary heating mechanism can be of the conduction type, blower type, or radiation type. The conduction type conducts heat to the recording medium from a component in contact with the recording medium. For example, a platen heater can be used. Although not shown, the platen heater is provided integrally with the platen 4. The blower type sends ambient temperature air or warm air to the recording medium to dry the ink. For example, a blower fan can be used. The radiation type heats the recording medium by radiating heat-generating radiation to it. For example, IR radiation can be used. Although not shown, a heater similar to the platen heater may be provided immediately downstream of the platen 4 in the SS direction. These primary heating mechanisms may be used individually or in combination.

[0153] For example, the primary heating mechanism includes an IR heater 3 and a platen heater.

[0154] Furthermore, by using the IR heater 3, the recording medium M can be heated radiantly by infrared radiation from the recording head 2 side. This makes it easier for the recording head 2 to be heated at the same time, but the temperature can be raised without being affected by the thickness of the recording medium M, compared to when the recording medium M is heated from the back surface using a platen heater or the like.The primary heating mechanism may also include various fans (e.g., ventilation fan 8) that blow warm air or air at the same temperature as the environment onto the recording medium M to dry the ink on the recording medium M.

[0155] The platen heater can heat the recording medium M via the platen 4 at a position facing the recording head 2. The platen heater is capable of heating the recording medium M by conduction and is used as needed in inkjet recording methods.

[0156] Furthermore, the inkjet recording device 1 may be equipped with a preheater 7 that preheats the recording medium M before ink is applied to the recording medium M.

[0157] (Post-heating mechanism) The system may also include a post-heating mechanism that performs a post-heating step after the ink application process to heat the recording medium, dry the ink, and fix it in place.

[0158] The heating element 5 used in the post-heating mechanism dries and solidifies the ink adhering to the recording medium M. By heating the recording medium M on which the image is recorded, the heating element 5 allows solvents and other substances contained in the ink to evaporate and dissipate more quickly. In this way, the recorded material can be obtained in a shorter time.

[0159] (Other configurations) The inkjet recording device 1 may have a cooling fan 6. After the ink recorded on the recording medium M dries, the ink on the recording medium M is cooled by the cooling fan 6, thereby forming an ink coating film with good adhesion on the recording medium M.

[0160] The recording device shown in Figure 1 is a serial printer that performs recording using a so-called serial method. The recording device may also be a line printer equipped with a line head that performs recording using a line method.

[0161] The line head has a nozzle row with multiple nozzles arranged in the width direction of the recording medium, and has a length greater than or equal to the width of the recording medium M being transported, allowing it to record an image in the width direction of the recording medium in a single pass. Recording can be performed in a single scan. Alternatively, after performing one scan while transporting the recording medium, it is possible to perform recording with two or more scans by returning the recording medium in the reverse direction of transport and transporting it again for another scan. The scanning may be performed by a head whose position is fixed relative to the transported recording medium, or by a head that moves while scanning is performed relative to the recording medium fixed in the platen area.

[0162] Furthermore, a recording device capable of line-type recording can be configured similarly to the one shown in Figure 1, except that the recording head 2 is replaced with a line head. Specifically, the heating mechanisms such as the ventilation fan 8, IR heater 3, platen heater, and preheater 7, which are located above the recording head 2 in Figure 1, can be similarly provided above or below the line head. Alternatively, a post-heating mechanism such as the heating heater 5 and cooling fan 6 shown in Figure 1 may also be provided.

[0163] 3. Examples The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" below refers to mass.

[0164] 3.1 Preparation of Non-Aqueous Inkjet Ink Compositions Each component was placed in a container to obtain the compositions shown in Tables 1 and 2 below, and thoroughly mixed and stirred to obtain the non-aqueous inkjet ink compositions for each example and comparative example. The units of the compositional values ​​in Tables 1 and 2 below are in mass%, and the total is 100.0 mass%. The luminous pigment is given as a solid content value, and a pigment dispersion prepared in advance by the method described below was used.

[0165] (Method for producing a pigment dispersion) First, a polyethylene terephthalate film with a smooth surface and a surface roughness Ra of 0.02 μm or less was prepared. Next, a release layer was formed on the entire surface of one side of this film by coating it with a release resin solubilized with acetone using a roll coater. The polyethylene terephthalate film with the release layer was transported into a vacuum deposition apparatus at a speed of 5 m / s, and a 15 nm thick film composed of Al was formed under reduced pressure. Next, the polyethylene terephthalate film with the Al film formed on it was immersed in tetrahydrofuran, and ultrasonic vibration at 40 kHz was applied to obtain a dispersion of metal powder, which is an aggregate of Al metal particles.

[0166] Tetrahydrofuran was removed using a centrifuge, and diethylene glycol diethyl ether (DEDG) was added to obtain a suspension containing 5% by mass of metal powder. Next, this suspension was treated with a circulating high-power ultrasonic grinder to grind the metal particles until the particle size was 0.5 μm. Ultrasound at 20 kHz was applied during this process.

[0167] Next, an amine-based dispersant (JEFFAMIN M2070) was added to the suspension to predisperse the metal particles. Furthermore, monostearyl phosphate, an alkyl phosphate, was added as a surface treatment agent. Then, the mixture was further dispersed by 40 kHz ultrasonic irradiation for 1 hour, and coarse particles were removed by filtration to obtain a metal pigment dispersion.

[0168] [Table 1]

[0169] [Table 2]

[0170] Further explanation is provided regarding the information in Tables 1 and 2 above. <composition> [Luminous pigments] The volume-average particle size (D50) was 0.5 μm, and the average thickness was 15 nm. The volume-average particle size (D50) was measured using a Microtrac MT-3300 (Microtrac-Bell, a laser diffraction / scattering particle size distribution analyzer). The average thickness was measured using atomic force microscopy with NanoNaviE-Sweep (SII Nanotechnology), and the average value was calculated from measurements of 50 arbitrary metal pigments. [Glycol monoether A] MFDG (Dipropylene glycol monomethyl ether, standard boiling point 189.6°C, surface tension 28.8 mN / m) BPG (propylene glycol monobutyl ether, standard boiling point 170.2°C, surface tension 26.8 mN / m) BMG (methylene glycol monobutyl ether, standard boiling point 171°C, surface tension 26.5 mN / m) MMB (3-methoxy-3-methylbutanol, standard boiling point 174°C, surface tension 29.9 mN / m) [Glycol monoether B] BTGH (tetraethylene glycol monobutyl ether, standard boiling point 290°C, surface tension 34.5 mN / m) MtetG (tetraethylene glycol monomethyl ether, standard boiling point 285°C, surface tension 34.7 mN / m) • MFTG (Tripropylene glycol monomethyl ether, standard boiling point 271°C, surface tension 30.8 mN / m) • EHDG (Diethylene glycol ethylhexyl ether, standard boiling point 302°C, surface tension 31.7 mN / m) • PhDG (Dipropylene glycol phenyl ether, standard boiling point 309°C, surface tension 40.1 mN / m) MTG (triethylene glycol monomethyl ether, standard boiling point 233.9°C, surface tension 33.4 mN / m) 〔others〕 GBL (γ-butyrolactone, standard boiling point 200°C, surface tension 41 mN / m) • DEDG (Diethylene glycol diethyl ether, standard boiling point 188°C, surface tension 26.9 mN / m) • Paraloid B60 (acrylic resin, product name of Dow Chemical Company) • BYK-333 (Silicon-based surface modifier, polyether-modified silicon compound, product name of BYK Additives & Instruments)

[0171] <term> "Glycol monoether A" is a compound represented by the following formula (1) and has a flash point of 85°C or lower. "Glycol monoether B" is a compound represented by the following formula (1) and has a flash point of 95°C or higher. R1-(O-R2) n -OH...Formula (1) (In formula (1), R1 is an alkyl group or phenyl group having 1 to 8 carbon atoms, R2 is an alkylene group having 1 to 5 carbon atoms, and n is an integer from 1 to 4.) • "fp" represents the flash point. • "Total Content (A+B)" represents the total content of glycol monoether A and glycol monoether B relative to the total amount of the ink composition. • The "mass ratio (A / B)" represents the ratio of the content of glycol monoether A to the content of glycol monoether B. • In terms of glossiness, "20 degrees" refers to the measurement of glossiness at a 20-degree reflection angle of the recording surface. • In terms of glossiness, "60 degrees" refers to the measurement of glossiness at a 60-degree reflection angle of the recording surface. The temperatures of "40°C" and "50°C" in the context of uneven printing represent the temperature of a heater located opposite the inkjet head during printing.

[0172] 3.2 Recording Conditions The non-aqueous inkjet ink composition obtained above was filtered and degassed, then filled into ink packs and installed as metallic ink in an inkjet printer ("SC-S80650," manufactured by Seiko Epson Corporation). In addition, commercially available color inks, particularly yellow ("SC10Y70," manufactured by Seiko Epson Corporation) or light cyan ("SC10LC70," manufactured by Seiko Epson Corporation), were similarly installed as colored ink compositions in the same printer. The printing medium used was polyvinyl chloride (Orajet-3165G).

[0173] The printed images were prepared as image data (resolution 1440 dpi) that digitized the overlay of metallic and color printing. The underlying metallic layer was a pattern image applied to the entire surface, and the upper color layer was printed with a 1 cm square pattern and fine lines of 1-3 mm to obtain the recorded material. For the underlying metallic printing, a nozzle usage rate of 70% was used, and for the upper color ink, patterns were used with nozzle usage rates varied from 20% to 100%. In addition, the printing temperature (heater temperature directly below the print head) was set to two levels, 40°C and 50°C, in order to judge the drying properties of the ink. However, for the recorded material used to evaluate glossiness, the printing temperature was set to 40°C.

[0174] 3.3 Evaluation Method 3.3.1 Glossiness (20 degrees) The recordings obtained above were evaluated using a MULTI Gloss 268 gloss meter (manufactured by Konica Minolta) to measure the glossiness of the recording surface at a 20° reflection, according to the following criteria. (Evaluation Criteria) A: 620 or more B: 580 or more, less than 620 C: Less than 580

[0175] 3.3.2 Glossiness (60 degrees) The recordings obtained above were evaluated using a MULTI Gloss 268 gloss meter (manufactured by Konica Minolta) to measure the glossiness of the recording surface at a 60° reflection, according to the following criteria. (Evaluation Criteria) A: 455 or higher B: Less than 455

[0176] 3.3.3 Unevenness (40℃) At a printing temperature of 40°C, the drying properties of metallic colors were evaluated by microscopic observation of the image quality of the upper layer of color ink in the recorded material obtained as described above, according to the following criteria. Since differences in drying properties are preferentially apparent in patterns where a bright yellow ink is formed on top of the metallic layer, the evaluation focused on the yellow hue and the coffee stain phenomenon, which is a challenge during the drying of colorants. (Evaluation Criteria) A: All colors are in good condition with no unevenness or yellowish discoloration. B: The color (yellow) shows dullness (likely due to the redissolution of the underlying metallic layer). C: The yellow color shows dullness and uneven coloring due to the coffee stain phenomenon. D: Dullness and coffee staining can also be observed in colors other than yellow.

[0177] 3.3.4 Unevenness (50℃) Except for setting the printing temperature to 50°C, the evaluation was performed using the same methods and criteria as for "unevenness (40°C)" described above.

[0178] 3.4 Evaluation Results The evaluation results are shown in Tables 1 and 2 above.

[0179] Each of the non-aqueous inkjet ink compositions in the embodiments of the present invention achieved both good gloss and good reduction of unevenness. In contrast, each of the comparative examples that were not based on the present invention showed inferiority in at least one of gloss or unevenness.

[0180] The following conclusions can be drawn from the embodiments described above.

[0181] One embodiment of a non-aqueous inkjet ink composition is: Luminous pigments and, It contains glycol monoether A and glycol monoether B, which are represented by the following formula (1) and have different flash points. The flash point of the glycol monoether A is 85°C or lower. The flash point of the glycol monoether B is 95°C or higher. The total content of glycol monoether A and glycol monoether B is 20 to 60% by mass relative to the total amount of the ink composition. The content of glycol monoether A is greater than the content of glycol monoether B. R1-(O-R2) n -OH...Formula (1) (In formula (1), R1 is an alkyl group or phenyl group having 1 to 8 carbon atoms, R2 is an alkylene group having 1 to 5 carbon atoms, and n is an integer from 1 to 4.)

[0182] In one embodiment of the above non-aqueous inkjet ink composition, The glycol monoether A may also have a C3 alkylene group in formula (1) where R2 is.

[0183] In any embodiment of the above non-aqueous inkjet ink composition, The glycol monoether B may also be tetraethylene glycol monobutyl ether.

[0184] In any embodiment of the above non-aqueous inkjet ink composition, Furthermore, it may also contain acrylic resin.

[0185] In any embodiment of the above non-aqueous inkjet ink composition, The aforementioned luminous pigment may be surface-treated with an alkyl phosphate.

[0186] In any embodiment of the above non-aqueous inkjet ink composition, Furthermore, it may contain a glycol diether represented by the following formula (2). R3O-(R4O) m -R5...Formula (2) (In formula (2), R3 and R5 are each independently alkyl groups having 1 to 4 carbon atoms, R4 is an alkylene group having 2 to 3 carbon atoms, and m is an integer from 1 to 4.)

[0187] In any embodiment of the above non-aqueous inkjet ink composition, The content of glycol monoether A may be 15 to 55% by mass relative to the total amount of the ink composition.

[0188] In any embodiment of the above non-aqueous inkjet ink composition, The content of glycol monoether B may be 5 to 15% by mass relative to the total amount of the ink composition.

[0189] In any embodiment of the above non-aqueous inkjet ink composition, The content of glycol monoether A relative to the content of glycol monoether B (A / B) may be 1.8 or more by mass ratio.

[0190] One method of recording is: The invention comprises a step of ejecting a non-aqueous inkjet ink composition according to any of the above embodiments and adhering it to a recording medium by an inkjet method.

[0191] The present invention is not limited to the embodiments described above, and various modifications are possible. For example, the present invention includes configurations that are substantially identical to the configurations described in the embodiments, for example, configurations that have the same function, method and result, or configurations that have the same purpose and effect. The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. Furthermore, the present invention includes configurations that produce the same effects or achieve the same purpose as the configurations described in the embodiments. Furthermore, the present invention includes configurations that add known technology to the configurations described in the embodiments. [Explanation of symbols]

[0192] 1... Inkjet recording device, 2... Recording head, 3... IR heater, 4... Platen, 5... Heating heater, 6... Cooling fan, 7... Preheater, 8... Ventilation fan.

Claims

1. Luminous pigments and, It contains glycol monoether A and glycol monoether B, which are represented by the following formula (1) and have different flash points. The flash point of the glycol monoether A is 85°C or lower. The flash point of the glycol monoether B is 95°C or higher. The total content of glycol monoether A and glycol monoether B is 20 to 60% by mass relative to the total amount of the ink composition. The content of glycol monoether A is greater than the content of glycol monoether B. The glycol monoether B is tetraethylene glycol monobutyl ether. Non-aqueous inkjet ink composition. R 1 - (O-R) 2 ) n -OH ・・・Form (1) (In formula (1), R 1 R is an alkyl group or phenyl group having 1 to 8 carbon atoms. 2 (where n is an alkylene group having 1 to 5 carbon atoms, and n is an integer from 1 to 4.)

2. The glycol monoether A is R of formula (1) 2 The non-aqueous inkjet ink composition according to claim 1, wherein is an alkylene group having 3 carbon atoms.

3. Furthermore, the non-aqueous inkjet ink composition according to claim 1 or claim 2 further contains an acrylic resin.

4. The non-aqueous inkjet ink composition according to any one of claims 1 to 3, wherein the luminous pigment is surface-treated with an alkyl phosphate.

5. Furthermore, the non-aqueous inkjet ink composition according to any one of claims 1 to 4, further comprising a glycol diether represented by the following formula (2). R 3 O-(R) 4 O) m -R 5 ・・・Form (2) (In formula (2), R 3 and R 5 Each of these is an alkyl group having 1 to 4 carbon atoms, and R 4 (where m is an alkylene group with 2 to 3 carbon atoms, and m is an integer from 1 to 4.)

6. The non-aqueous inkjet ink composition according to any one of claims 1 to 5, wherein the content of glycol monoether A is 15 to 55% by mass with respect to the total amount of the ink composition.

7. The non-aqueous inkjet ink composition according to any one of claims 1 to 6, wherein the content of the glycol monoether B is 5 to 15% by mass with respect to the total amount of the ink composition.

8. A non-aqueous inkjet ink composition according to any one of claims 1 to 7, wherein the content of glycol monoether A (A / B) to the content of glycol monoether B is 1.8 or more by mass ratio.

9. A recording method comprising the step of ejecting a non-aqueous inkjet ink composition according to any one of claims 1 to 8 by an inkjet method and adhering it to a recording medium.

Images