Non-aqueous inkjet ink composition and recording method

Abstract

Provided is a non-aqueous inkjet ink composition and recording method that can achieve both good gloss and good unevenness reduction. A non-aqueous inkjet ink composition according to an embodiment of the present invention contains a luster pigment, and diol monoethers A and B represented by the following formula (1) that differ in flash point, the flash point of the diol monoether A being 85°C or lower, the flash point of the diol monoether B being 95°C or higher, the total content of the diol monoether A and the diol monoether B being 20 to 60% by mass relative to the total amount of the ink composition, and the content of the diol monoether A being greater than the content of the diol monoether B.R1‑(O‑R2) n ‑OH … Formula (1)In formula (1), R1 is an alkyl group having 1 to 8 carbon atoms or a phenyl group, R2 is an alkylene group having 1 to 5 carbon atoms, and n is an integer of 1 to 4.

Description

TECHNICAL FIELD

[0001] The present application relates to a non-aqueous inkjet ink composition and a recording method. BACKGROUND

[0002] Inkjet recording methods have rapidly developed in various aspects, since they can record high-definition images with relatively simple apparatuses. In recent years, liquid droplets of ink and the like that coat more minute dots at high density are required to print higher-definition images at high speed. Among them, attempts have been made to record images having metallic luster, and metallic inks that enable higher-gloss printing are being developed.

[0003] For example, Patent Literature 1 has developed a non-aqueous inkjet ink composition containing a lustrous pigment, a specific glycol diether having a flash point of 70°C or lower, and a specific glycol monoether.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Laid-Open No. 2016-150984

[0007] However, the obtained recording material is insufficient in luster, and in the case where a color ink is printed on an upper layer of an image formed by a metallic ink, unevenness occurs if the printing speed is made faster. That is, it is not possible to achieve both good luster and good reduction in unevenness. SUMMARY

[0008] One aspect of the non-aqueous inkjet ink composition according to the present application contains a lustrous pigment, and a glycol monoether A and a glycol monoether B that are represented by the following formula (1) and have different flash points from each other,

[0009] the flash point of the glycol monoether A is 85°C or lower,

[0010] the flash point of the glycol monoether B is 95°C or higher,

[0011] the total content of the glycol monoether A and the glycol monoether B is 20 to 60% by mass relative to the total amount of the ink composition,

[0012] the content of the glycol monoether A is more than the content of the glycol monoether B,

[0013] R1-(O-R2) n -OH formula (1)

[0014] (In formula (1), R1 is an alkyl group having 1 to 8 carbon atoms or a phenyl group, R2 is an alkylene group having 1 to 5 carbon atoms, and n is an integer of 1 to 4.)

[0015] One embodiment of the recording method according to the present application includes a step of ejecting the non-aqueous inkjet ink composition according to the above-mentioned one embodiment by an inkjet method and adhering it to a recording medium. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a schematic view of one example of a recording apparatus that can be used in the recording method according to the present application.

[0017] SYMBOL DESCRIPTION

[0018] 1: inkjet recording apparatus; 2: recording head; 3: IR heater; 4: platen; 5: heater; 6: cooling fan; 7: preheater; 8: ventilation fan. DETAILED DESCRIPTION

[0019] Hereinafter, embodiments of the present application will be described. The embodiments described below illustrate examples of the present application. The present application is not limited to any of the embodiments described below, and includes various modifications implemented within a scope that does not change the gist of the present application. Note that the configurations described below are not necessarily all essential configurations of the present application.

[0020] 1. Non-aqueous inkjet ink composition

[0021] The non-aqueous inkjet ink composition according to one embodiment of the present application contains a lustrous pigment, and diol monoether A and diol monoether B represented by the following formula (1) that have different flash points, the flash point of the diol monoether A is 85°C or lower, the flash point of the diol monoether B is 95°C or higher, the total content of the diol monoether A and the diol monoether B is 20 to 60 mass% with respect to the total amount of the ink composition, and the content of the diol monoether A is more than the content of the diol monoether B.

[0022] R1-(O-R2) n -OH … Formula (1)

[0023] In formula (1), R1is an alkyl group having 1 to 8 carbon atoms or a phenyl group, R2is an alkylene group having 1 to 5 carbon atoms, and n is an integer of 1 to 4.

[0024] Currently, in metal printing, the size of the pigment of the metal ink is increased within the range in which the ink can be ejected, and the drying time of the ink is increased by a slower printing speed. That is, since the pigment of a larger size is relatively large with respect to the nozzle hole of the inkjet head, the printing stability of a high frequency is reduced, and thus the printing speed needs to be reduced. This is because, firstly, it is difficult to uniformly and finely reduce the metal pigment to a very fine size, and secondly, the productivity of the crushing process is low, and it is very time-consuming. Further, as a reason for the drying time, when the size of the pigment is large, a continuous reflective surface without a seam can be formed, and thus a high gloss is easily obtained, but on the other hand, the flowability is sacrificed, and the ability of the pigment to appropriately arrange on the surface of the recording medium (hereinafter, also referred to as "floating property" or "orientation ability") when the ink is dried is not high, and thus it is not easy to eliminate the overlapping of the pigments and the like under conditions in which the drying is fast. However, such a method cannot perform high-speed printing, and in addition, the glossiness is not sufficient.

[0025] Further, in recent years, in the inkjet recording method, it is further required to coat liquid droplets of even smaller ink and the like at a high density to print a higher definition image at a high speed. Therefore, even in the metal ink, even in the case where the size of the pigment is further reduced to cope with high-definition printing and high-speed printing is performed, it is required to be excellent in glossiness, but it is difficult to achieve a higher glossiness than in the past due to the following reasons.

[0026] (i) Small particle size of the pigment: When the size of the bright pigment is further reduced to cope with high-definition printing, the aspect ratio of the pigment easily becomes small. Such a pigment is good in flowability per particle, but it is difficult to form a reflective surface with less seams parallel to the printing surface, and thus the glossiness easily becomes poor. In addition, in terms of dispersibility, since the relative specific surface area with respect to the weight of the particles increases, if the repulsion between the particles is reduced due to the influence of heat and moisture and the like, the dispersibility easily decreases, the pigment is aggregated and floats, and the glossiness decreases.

[0027] (ii) Swelling of the recording medium due to solvent penetration: In general, the metal ink contains a glycol ether-based solvent (sometimes further contains a polar solvent) and the like as a solvent. These solvents also have an effect of swelling the surface of the recording medium to impart ink adhesiveness. On the other hand, the swelling causes the surface of the recording medium to have unevenness, and thus the glossiness (particularly, gloss at a low angle such as 20 degrees) easily decreases.

[0028] (iii) Drying speed: In high-speed printing, since the ejected ink droplets are smaller, the ink easily dries on the recording medium quickly, and it is difficult to ensure time for sufficient floating. On the other hand, in the case where a color ink is printed on the upper layer of an image formed by a metallic ink, particularly in high-speed printing, in order to reduce bleeding and unevenness caused by the color printing of the upper layer, and sometimes color mixing and darkening caused by re-dissolution to the color printing, it is necessary for the metallic layer of the substrate to dry quickly. That is, in order to obtain high glossiness, it is necessary to reduce the drying speed, on the other hand, in order to reduce unevenness, it is necessary to increase the drying speed, and it is difficult to satisfy both.

[0029] The non-aqueous inkjet ink composition according to the present embodiment, by containing the specific glycol monoether in a specific amount relationship, can maintain appropriate adhesiveness, while reducing the unevenness caused by swelling on the recording medium, and appropriately adjusting the drying speed of the ink, to obtain high glossiness and good unevenness reduction. By containing the above glycol monoether A, the drying property of the ink can be improved, while suppressing the influence on the recording medium such as swelling, to obtain moderate adhesiveness. In addition, the above glycol monoether B contributes to good reduction of the drying property of the ink, and can ensure the time for pigment floating. Furthermore, the above glycol monoether B reduces the drying of the nozzle, and can also stabilize the intermittent printing stability, and thus can maintain high printing accuracy. By having the content of the above glycol monoether A be more than the content of the above glycol monoether B, an appropriate drying speed is obtained, and high glossiness and good unevenness reduction can be obtained.

[0030] In the present application, "non-aqueous" means that water is not the main solvent component, and water is not contained as a functional component for functioning and performance of the ink. The content of water is 5% by mass or less, preferably 3% by mass or less, further preferably 1% by mass or less, particularly preferably 0.5% by mass or less, more preferably 0.1% by mass or less, with respect to the total amount of the non-aqueous inkjet ink composition, and water can not be contained. The content of the organic solvent of the non-aqueous inkjet ink composition is preferably 50% by mass or more, more preferably 70 to 98% by mass.

[0031] In the present application, "inkjet ink composition" means an ink composition for inkjet. Note that inkjet is a recording method in which liquid droplets such as ink are ejected from a nozzle of an inkjet head of an inkjet recording device or the like and are imparted to a recording medium. In the following description, "inkjet ink composition" is also referred to simply as "ink composition" and "ink".

[0032] 1.1 Glossy pigment

[0033] The non-aqueous inkjet ink composition according to the present embodiment contains a glossy pigment. The glossy pigment has a function of imparting glossiness to a pattern attached and formed on a recording medium.

[0034] 1.1.1 Pigment

[0035] As the luster pigment, for example, metallic pigments and pearl pigments can be mentioned. The luster pigment can be used singly or in combination of two or more.

[0036] As the metallic pigment, for example, particles of aluminum, silver, gold, platinum, nickel, chromium, tin, zinc, indium, titanium, copper, particles of alloys thereof, and mixtures thereof can be mentioned.

[0037] As the pearl pigment, for example, pigments having a pearl luster or interference luster such as titanium dioxide-coated mica, fish scale foil, and bismuth oxychloride can be mentioned.

[0038] The shape of the luster pigment is not particularly limited, and for example, flat plate shape, spherical shape, spindle shape, needle shape can be mentioned. Among them, the flat plate shape is preferred. By making the luster pigment flat plate shape, it is possible to arrange the luster pigment on the recording medium to which the ink composition is attached in such a manner that the major surface follows the surface shape of the recording medium, and it is possible to more effectively exhibit the original luster and the like of the luster pigment.

[0039] In the present embodiment, the "flat plate shape" means a shape in which the area when viewed from a predetermined angle (plan view) is larger than the area when viewed from an angle orthogonal to the viewing direction. With respect to the shape of one luster pigment, the ratio (S1 / S0) of the projected maximum area S1 [μm 2 ] to the orthogonal maximum area S0 [μm 2 ] is preferably 2.0 or more, more preferably 5.0 or more, and further preferably 8.0 or more. The projected maximum area means the area when viewed from the direction in which the projected area is the largest and plan view. The orthogonal maximum area means the area when viewed from the direction in which the area is the largest among the directions orthogonal to the viewing direction of the projected maximum area and plan view. As this value, for example, the average value of the values obtained by observing any 10 particles and calculating with respect to these particles can be adopted.

[0040] The luster pigment of the present embodiment preferably contains aluminum. By using aluminum, the luster of the printed image obtained from the ink composition is excellent, and the raw material cost is also excellent. Note that the luster pigment can contain at least aluminum, and can further contain other metals.

[0041] The luster pigment of the present embodiment preferably contains a metal particle. The metal particle can include at least a region near the surface composed of a metal or a metal alloy (hereinafter, also simply referred to as "metal"). The metal particle can be composed of a metal throughout, or can have a core portion composed of a non-metal material and a film composed of a metal covering the core portion. The metal particle is preferably the above-mentioned metallic pigment.

[0042] The metal particles of the lustrous pigment can be produced by any method. The metal particles are preferably particles obtained, for example, by forming a film of metal on one side of a sheet-like substrate by a vapor deposition method, then peeling off and pulverizing the film of metal from the sheet-like substrate. Instead of the vapor deposition method, ion plating or sputtering method can also be used. According to this method, metal particles in the form of flat plates can be obtained, and thus the original luster of the metal particles can be more effectively exhibited.

[0043] The sheet-like substrate is not particularly limited, and a plastic film such as polyethylene terephthalate can be used. In order to improve the peeling property, a release agent such as silicone oil can be applied to the film- forming surface of the sheet-like substrate in advance, or a peeling resin layer can be formed in advance. The resin used for the peeling resin layer is not particularly limited, and examples include polyvinyl alcohol, polyvinyl butyral, polyethylene glycol, polyacrylic acid, polyacrylamide, cellulose derivatives such as cellulose acetate butyrate, and modified nylon resin. The peeling and pulverization are performed, for example, by irradiating the film of metal with ultrasonic waves in a non-aqueous medium, or by applying an external force by stirring with a homogenizer.

[0044] The non-aqueous medium used for the peeling and pulverization is not particularly limited, and examples include alcohol solvents, hydrocarbon solvents, and ether solvents. Among them, ether solvents are preferred. The ether solvent is not particularly limited, and 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 dioxane. Among them, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and diethylene glycol methyl ethyl ether are preferred, and diethylene glycol diethyl ether is more preferred.

[0045] 1.1.2 Surface treatment agent

[0046] The luster pigment is preferably a metal particle surface-treated with a surface treatment agent. By applying surface treatment with a surface treatment agent, it is possible to effectively suppress the reaction of the metal particle with water, and also to obtain a luster pigment having excellent dispersibility. Note that it is presumed that in the luster pigment surface-treated with a surface treatment agent, a part of the phosphorus-containing acid group of the surface treatment agent is chemically bonded to the surface of the metal particle. At this time, it is not necessarily the case that the surface treatment agent itself is bonded to the surface of the metal particle by hydrogen bonding or intermolecular forces, but the metal particle can have a residue of the surface treatment agent. That is, it is considered that in the luster pigment surface-treated with a surface treatment agent, the OH group present on the surface of the metal particle reacts with a part of the phosphorus-containing acid group of the surface treatment agent, and the metal particle and the surface treatment agent are bonded by a covalent bond. Alternatively, the surface treatment agent can be attached to the surface of the metal particle by physical adsorption or the like. In this way, it is considered that the surface treatment agent is attached to the metal particle by bonding or physical adsorption or the like.

[0047] The surface treatment agent is not particularly limited, and examples thereof include fluorine-based compounds and alkyl phosphates. Among these, the luster pigment is preferably surface-treated with an alkyl phosphate. An alkyl phosphate easily uniformly performs surface treatment on the surface of a metal particle, and enables the formation of a stable and dense film. Thus, there is a tendency that the dispersibility and the luster of the luster pigment are further improved.

[0048] The fluorine-based compound is not particularly limited, and examples thereof include fluorine-based phosphonic acids, fluorine-based carboxylic acids, fluorine-based sulfonic acids, fluorine-based silanes, and salts thereof.

[0049] The alkyl phosphate preferably contains, for example, at least one or more selected from the group consisting of a compound represented by formula (3) and a compound represented by formula (4).

[0050] (R-O-)P(O)(OH)2... Formula (3)

[0051] (R-O-)2P(O)(OH)... Formula (4)

[0052] In the formula, R is independently a hydrocarbon group having 8 or more carbon atoms.

[0053] The compound (monomer) represented by the above formula (3) is a compound in which one of the three hydroxyl groups of phosphoric acid is esterified with an R group. Such a monomer easily uniformly performs surface treatment on the surface of a metal particle because of its small steric hindrance, and in particular, can provide a luster pigment having excellent dispersibility and luster. The compound (dimer) represented by the above formula (4) is a compound in which two of the three hydroxyl groups of phosphoric acid are esterified with an R group. Such a dimer is difficult to allow water to approach the surface of a luster pigment because of its large steric hindrance, and in particular, can provide a luster pigment having excellent water resistance.

[0054] In the above formula (3) and formula (4), R is a hydrocarbon group having a carbon skeleton with a carbon atom number of 8 or more, and is a hydrocarbon group having a skeleton in which 8 or more carbon atoms are continuously bonded. Note that in the above formula (3) and formula (4), any carbon atom of the carbon skeleton with a carbon atom number of 8 or more of R is directly bonded to an oxygen atom of O of (R-O-), and the oxygen atom is directly bonded to a phosphorus atom of P.

[0055] Therefore, when the surface treatment agent reacts with the metal particles through the part of the hydroxyl group of the surface treatment agent that is bonded to the phosphorus atom and the surface of the metal particles is modified, it is presumed that R can exist in a position close to the metal particles, and the dispersion stability of the lustrous pigment can be excellent.

[0056] Furthermore, it is presumed that by making R a longer chain hydrocarbon group, the lustrous pigment can be given excellent dispersion stability.

[0057] As the hydrocarbon group having a carbon skeleton with a carbon atom number of 8 or more, a saturated hydrocarbon group having no double bond or triple bond between carbons, an unsaturated hydrocarbon group having a double bond or a triple bond between carbons, and the like can be given. The hydrocarbon group of R can be an aromatic hydrocarbon group having an aromatic ring structure in the carbon skeleton, a chain or cyclic aliphatic hydrocarbon group, or the like. In particular, a chain aliphatic hydrocarbon group is more excellent in dispersion stability and the like, and is therefore preferred. The chain aliphatic hydrocarbon group can be a branched chain type or a straight chain type, and in terms of being more excellent in dispersion stability, jetting stability, gloss, and the like, a straight chain type is preferred. In this case, for example, since a plurality of alkyl phosphates can be modified on the surface of the metal particles, it is presumed that a sufficient effect will be obtained.

[0058] R is a hydrocarbon group, and therefore has a bond between a carbon atom and a hydrogen atom. In the case where R has no substituent, R is a hydrocarbon group composed of carbon atoms and hydrogen atoms. For example, in the case where R is a chain aliphatic hydrocarbon group, an alkyl group, an alkenyl group, an alkynyl group, and the like can be given. In this case, when it is a non-aqueous ink, dispersion stability is more excellent, and therefore is preferred.

[0059] R is a hydrocarbon group having a carbon skeleton with a carbon atom number of 8 or more, and contains carbon atoms and hydrogen atoms, and at least has a bond between a carbon atom and a hydrogen atom. Therefore, a part of the hydrogen atoms of the hydrocarbon group of R can be substituted with a substituent, as long as R has one or more unsubstituted hydrogen atoms.

[0060] As the substituent, a carboxyl group, a hydroxyl group, an amino group, an oxygen-containing alkylene group, a fluorinated group, and the like can be given. In particular, in the case of being substituted with a fluorinated group or the like, the lustrous pigment is given higher hydrophobicity, and is more preferred from the viewpoints of water resistance and gloss. Note that the oxygen-containing alkylene group is a group having an oxygen alkylene structure, and the oxygen alkylene structure can also be referred to as an alkylene oxide structure.

[0061] In the case where a part of the hydrogen atoms of the hydrocarbon group of R can be substituted with a substituent, the number of substituents is preferably 50% or less, more preferably 10% or less, of the number of hydrogen atoms of the hydrocarbon group of R in the case where R has no substituent. In addition, the number of substituents is preferably five or less, particularly preferably three or less. Further preferably, the number of substituents is two or less, more preferably one or less. In addition, the number of substituents is 0 or more, and the lower limit of the number of substituents in the case where a part of the hydrogen atoms of the hydrocarbon group of R is substituted with a substituent is one or more. When the substituent is provided to the carbon atom located at the position farthest from the phosphorus atom in the formula, there is a tendency that the dispersion stability is more excellent, and thus it is preferable.

[0062] In the compounds represented by the above formula (3) and formula (4), R in the formula is preferably a hydrocarbon group having 10 or more carbon atoms. In addition, R in the formula is more preferably a hydrocarbon group having 12 to 30 carbon atoms. Furthermore, the number of carbon atoms of the hydrocarbon group of R in the formula is more preferably 12 to 25, further preferably 12 to 23, more further preferably 14 to 22, particularly preferably 15 to 20, more particularly preferably 17 to 20. When the number of carbon atoms of the hydrocarbon group of R in the formula is particularly in the range of 15 to 20, preferably in the above range, there is a tendency that the water resistance and the gloss are more excellent.

[0063] Note that R in the above formula (3) and formula (4) is preferably a hydrocarbon group having the same number of carbon atoms, more preferably R is a hydrocarbon group that is the same. When R is such, it is presumed that the alkyl phosphates are uniformly attached to the surface of the metal particles, and there is a tendency that the water resistance and the gloss balance are favorably good.

[0064] In addition, R in the above formula (3) and formula (4) is any one of an alkyl group, an alkenyl group, and an alkynyl group, more preferably a carbon skeleton having 10 or more carbon atoms. In this case, it is preferable that the carbon skeleton have 10 or more and 30 or less carbon atoms. Furthermore, the number of carbon atoms of the carbon skeleton is preferably 10 or more and 25 or less, more preferably 12 or more and 23 or less, further preferably 14 or more and 21 or less, particularly preferably 16 or more and 19 or less. When R is any one of an alkyl group, an alkenyl group, and an alkynyl group, and the number of carbon atoms is in the above range, there is a tendency that the dispersion stability and the gloss are more excellent.

[0065] As specific examples of the compound (monomer) represented by the above formula (3), monooctyl phosphate, monolauryl phosphate, mono-isotridecyl phosphate, and monostearyl phosphate can be given, and one or more thereof is preferably selected. More preferably, one or more of mono-isotridecyl phosphate and monostearyl phosphate is selected, and further preferably, monostearyl phosphate is selected.

[0066] As the compound represented by the above formula (4) (dibasic compound), as specific examples, there can be mentioned: dioctyl phosphate, dilauryl phosphate, diisotridecyl phosphate, distearyl phosphate, and preferably one or more selected from among these. More preferably, one or more selected from among diisotridecyl phosphate and distearyl phosphate, and further preferably distearyl phosphate.

[0067] As the surface treatment of the metal particles with the surface treatment agent, for example, the surface treatment agent can be previously contained in a liquid when the metal particles are formed by pulverizing a film made of metal formed by use of a vapor deposition method in the liquid.

[0068] The content of the surface treatment agent is preferably 1 to 100 mass%, more preferably 1 to 70 mass%, further preferably 1 to 50 mass%, still further preferably 2 to 40 mass%, particularly preferably 4 to 30 mass%, more particularly preferably 6 to 20 mass%, and further particularly preferably 8 to 15 mass%, relative to 100 mass% of the total mass of the metal particles.

[0069] In the case where the surface treatment is performed with the compound represented by the above formula (3) as the alkyl phosphate, the content thereof is preferably 0.5 to 90 mass%, more preferably 0.5 to 70 mass%, further preferably 1 to 50 mass%, still further preferably 2 to 30 mass%, particularly preferably 3 to 20 mass%, and more particularly preferably 4 to 15 mass%, relative to 100 mass% of the total mass of the metal particles. When the content of the compound represented by the above formula (3) is within the above range relative to 100 mass% of the total mass of the metal particles, there is a tendency that the dispersibility and the gloss of the lustrous pigment are more excellent.

[0070] In the case where the surface treatment is performed with the compound represented by the above formula (4) as the alkyl phosphate, the content thereof is preferably 0.05 to 30 mass%, more preferably 0.1 to 25 mass%, further preferably 1 to 20 mass%, still further preferably 2 to 15 mass%, and particularly preferably 3 to 10 mass%, relative to 100 mass% of the total mass of the metal particles. When the content of the compound represented by the above formula (4) is within the above range relative to 100 mass% of the total mass of the metal particles, there is a tendency that the water resistance is more excellent.

[0071] 1.1.3 Physical properties and the like

[0072] The lustrous pigment preferably has a volume average particle diameter (D50) of 0.5 μm or less and an average thickness of 30 nm or less. In addition, the aspect ratio (volume average particle diameter (D50) / average thickness) of the lustrous pigment is preferably 15 to 60, more preferably 20 to 50, and further preferably 30 to 40. Such a lustrous pigment has low floatability and also tends to have reduced dispersibility, and thus tends to have deteriorated luster. However, according to the non-aqueous inkjet ink composition according to the present embodiment, even such a lustrous pigment can provide good luster.

[0073] The lower limit of the volume average particle diameter (D50) of the lustrous pigment is not particularly limited, and is preferably 0.10 μm or more, more preferably 0.20 μm or more, further preferably 0.25 μm or more, and particularly preferably 0.30 μm or more. In addition, the upper limit of the volume average particle diameter (D50) of the lustrous pigment is not particularly limited, and can be 5.00 μm or less, can be 3.00 μm or less, can be 1.00 μm or less, can be 0.70 μm or less, and is preferably 0.55 μm or less.

[0074] In the present application, the "volume average particle diameter (D50)" refers to the median particle diameter of the volume distribution of a lustrous pigment dispersion liquid measured by a laser diffraction / scattering method, and is the size of the particle that shows exactly 50% of the central value in terms of cumulative count when a plurality of measurement results are expressed as the presence ratio of each size. Note that in the case where the shape of the lustrous pigment is a flat plate shape, the volume average particle diameter is the particle diameter obtained based on the shape and size of the lustrous pigment after spherical conversion.

[0075] The lower limit of the average thickness of the lustrous pigment is not particularly limited, and is preferably 5 nm or more, more preferably 7 nm or more, further preferably 9 nm or more, particularly preferably 11 nm or more, and more particularly preferably 13 nm or more. In addition, the upper limit of the average thickness of the lustrous pigment is not particularly limited, and can be 60 nm or less, can be 40 nm or less, is preferably 25 nm or less, more preferably 23 nm or less, further preferably 21 nm or less, particularly preferably 19 nm or less, and more particularly preferably 17 nm or less. The average thickness of the lustrous pigment is particularly preferably 15 nm.

[0076] The average thickness of the lustrous pigment can be measured using an atomic force microscope (AFM). For example, it can be measured by an atomic force microscope method using NanoNavi E-Sweep (manufactured by SII Nano Technology Inc.), but is not limited thereto. For example, it is measured for any 50 lustrous pigments, and the average value thereof is taken. That is, the average thickness is preferably the arithmetic average thickness.

[0077] 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, further preferably 0.5% by mass or more, particularly preferably 0.7% by mass or more, and more 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, further preferably 2% by mass or less, particularly preferably 1.7% by mass or less, and more 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, there is a tendency that the storage stability, water resistance, and the like of the ink composition are more excellent, and the gloss, scratch resistance, and the like of the colored portion formed using the ink composition are particularly excellent.

[0078] 1.2 Diol monoethers

[0079] The non-aqueous inkjet ink composition according to the present embodiment contains diol monoethers A and B represented by the following formula (1) having different flash points.

[0080] R1-(O-R2) n -OH … Formula (1)

[0081] In formula (1), R1is an alkyl group having 1 to 8 carbon atoms or a phenyl group, R2is an alkylene group having 1 to 5 carbon atoms, and n is an integer of 1 to 4.

[0082] R1and R2in the above formula (1) can be branched or linear. As R1, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, t-butyl, and the like can be exemplified. As R2, for example, methylene, ethylene (dimethylene), propylene (trimethylene or methyl ethylene), butylene, and the like can be exemplified.

[0083] In this connection, the "flash point" is defined in JIS K2265 as "the lowest temperature at which the vapor of a sample ignites momentarily when an ignition source is brought near the vapor, and the flame spreads over the surface of the sample, after the temperature of the sample is corrected to 101.3 kPa value". That is, the flash point is determined in accordance with the ease of volatilization of the sample and the flammability of the gas after volatilization, and the vapor pressure at a lower temperature is taken into consideration. In contrast, the normal boiling point is the boiling point at a pressure of 1 atm, and the vapor pressure at a higher temperature is taken into consideration. At this time, it was confirmed through experiments that the correlation of the drying speed of a liquid was higher with the flash point than with the normal boiling point. This is because the relationship (slope) between the low-temperature vapor pressure and the high-temperature vapor pressure of different compounds is different, and the temperature in the printing process is on the lower temperature side of 23 to 40°C, and therefore it is presumed that the flash point closer to the temperature of the printing process has a higher correlation with the drying speed.

[0084] Note that, in the case where the flash point obtained by the Tag closed cup flash point tester is more than 80°C, the flash point is preferably measured by the Cleveland open cup flash point tester, and in the case where the flash point obtained by the Tag closed cup flash point tester is 80°C or less, the flash point is preferably measured by the Tag closed cup flash point tester when the kinematic viscosity of the solvent at the flash point is less than 10 cSt, and the flash point is preferably measured by the Setaflash closed cup flash point tester when the kinematic viscosity of the solvent at the flash point is 10 cSt or more.

[0085] 1.2.1 Diol monoether A

[0086] The diol monoether A contained in the non-aqueous inkjet ink composition according to the present embodiment has a flash point of 85°C or less, and is preferably represented by the following formula (1)'.

[0087] R1-(O-R2) n -OH Formula (1)'

[0088] In formula (1)', R1is an alkyl group having 1 to 4 carbon atoms, R2is an alkylene group having 1 to 5 carbon atoms, and n is an integer of 1 to 4.

[0089] The diol monoether A described above can improve the drying property of the ink while suppressing the influence on the recording medium such as swelling, and can obtain a moderate close contact property.

[0090] The lower limit of the flash point of the diol monoether A described above is not particularly limited, and is preferably 30°C or more, more preferably 50°C or more, further preferably 60°C or more, and particularly preferably 70°C or more. The upper limit of the flash point of the diol monoether A described above is preferably 83°C or less, and further preferably 80°C or less. When the flash point is within the range described above, sometimes a more excellent gloss property can be obtained.

[0091] As the diol monoether A described above, R2in formula (1)' described above is preferably an alkylene group having 2 to 3 carbon atoms, and particularly preferably an alkylene group having 3 carbon atoms. In the case of this diol monoether A, there is a tendency that the influence on the recording medium such as swelling can be more reduced, and a more excellent gloss property can be obtained. In addition, the dispersibility of the lustrous pigment can be made excellent.

[0092] As the diol monoether A described above, R1in formula (1)' described above is preferably an alkyl group having 1 to 2 carbon atoms, and more preferably an alkyl group having 1 carbon atom. In the case of this diol monoether A, sometimes a more excellent gloss property and unevenness reduction property can be obtained.

[0093] As the diol monoether A described above, n in formula (1)' described above is preferably 1 to 3, more preferably 1 to 2, and n is further preferably 2. In the case of this diol monoether A, sometimes a more excellent gloss property and unevenness reduction property can be obtained.

[0094] As a specific compound of the above-mentioned diol monoether A, for example, 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), 3-methoxy-3-methylbutanol (MMB, 68°C) (flash point in parentheses) can be exemplified. Of these, the above-mentioned diol monoether A is preferably one or more selected from the group consisting of methylene glycol monobutyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, 3-methoxy-3-methylbutanol, and particularly preferably dipropylene glycol monomethyl ether. When it is this diol monoether A, there is a tendency that the drying property of the ink can be more favorably improved, while the influence on the recording medium such as swelling is more suppressed, and a more moderate close contact is obtained.

[0095] The content of the above-mentioned diol monoether A is preferably 15 to 55% by mass, more preferably 15 to 40% by mass, further preferably 15 to 30% by mass, and particularly preferably 15 to 25% by mass, relative to the total amount of the ink composition. When the content of the above-mentioned diol monoether A is within the above-mentioned range, there is a tendency that a more favorable gloss and reduction in unevenness are obtained.

[0096] 1.2.2 Diol Monoether B

[0097] The diol monoether B contained in the non-aqueous inkjet ink composition according to the present embodiment has a flash point of 95°C or higher, and is preferably represented by the following formula (1)".

[0098] R1-(O-R2)n n -OH... Formula (1)"

[0099] In formula (1)", R1is an alkyl group having 1 to 8 carbon atoms or a phenyl group, R2is an alkylene group having 1 to 4 carbon atoms, and n is an integer of 1 to 4.

[0100] The above-mentioned diol monoether B is a solvent that is relatively difficult to dry, and is useful in favorably reducing the drying property of the ink, and in ensuring the time for which the pigment floats.

[0101] The upper limit of the flash point of the above-mentioned diol monoether B is not particularly limited, and for example, it is preferably 200°C or lower, more preferably 180°C or lower, further preferably 170°C or lower, and particularly preferably 160°C or lower. The lower limit of the flash point of the above-mentioned diol monoether A is preferably 110°C or higher, more preferably 120°C or higher, further preferably 130°C or higher, particularly preferably 140°C or higher, and more particularly preferably 150°C or higher. When the flash point is within the above-mentioned range, a more favorable gloss is sometimes obtained.

[0102] As the above-mentioned diol monoether B, R1 of the above-mentioned formula (1)" is preferably an alkyl group having 1 to 2 carbon atoms, and more preferably an alkyl group having 1 carbon atom. In the case of this diol monoether B, more excellent gloss and unevenness reduction can be obtained.

[0103] As the above-mentioned diol monoether B, R2 of the above-mentioned formula (1)" is preferably an alkylene group having 2 to 3 carbon atoms, and more preferably an alkylene group having 2 carbon atoms. In the case of this diol monoether B, more excellent gloss and unevenness reduction can be obtained at times.

[0104] As the above-mentioned diol monoether B, n of the above-mentioned formula (1)" is preferably 2 to 4, more preferably 3 to 4, and further preferably 4. In the case of this diol monoether B, more excellent gloss and unevenness reduction can be obtained at times.

[0105] Specific compounds of the above-mentioned diol monoether B are not particularly limited, and examples thereof 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), tripropylene glycol monomethyl ether (MFTG, 117.6°C) (the flash point is shown in parentheses). Among these, the above-mentioned diol monoether B is preferably one or more selected from the group consisting of 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. In the case where the above-mentioned diol monoether B is tetraethylene glycol monobutyl ether, the floatability is more excellent, and the gloss can be further improved. This is because tetraethylene glycol monobutyl ether has a higher polarity, and can more preferably float in the interaction with the surface of a glossy pigment having a low surface free energy. In addition, tetraethylene glycol monobutyl ether has a small influence on the recording medium, and hardly swells the recording medium, and can suppress the reduction in gloss due to the unevenness of the surface.

[0106] The content of the above-mentioned diol monoether B is preferably 5 to 15% by mass, more preferably 8 to 13% by mass, and further preferably 9 to 12% by mass, with respect to the total amount of the ink composition. When the content of the above-mentioned diol monoether B is within the above-mentioned range, there is a tendency to obtain more excellent gloss and unevenness reduction.

[0107] 1.2.3 Content

[0108] In the non-aqueous inkjet ink composition according to the present embodiment, the total content of the above-described glycol monoether A and the above-described glycol monoether B is 20 to 60% by mass relative to the total amount of the ink composition, and the content of the above-described glycol monoether A is more than the content of the above-described glycol monoether B.

[0109] By containing the above-described glycol monoether A and the above-described glycol monoether B in a specific amount relationship, a moderate close contact is maintained while reducing unevenness caused by swelling of the recording medium, and the drying speed of the ink is appropriately adjusted, resulting in high glossiness and good unevenness reduction.

[0110] The total content of the above-described glycol monoether A and the above-described glycol monoether B is preferably 20 to 55% by mass, more preferably 20 to 50% by mass, further preferably 20 to 45% by mass, more further preferably 20 to 40% by mass, particularly preferably 23 to 40% by mass, and more particularly preferably 25 to 35% by mass, relative to the total amount of the ink composition. When the total content is within the above-described range, there is a tendency to obtain higher glossiness and good unevenness reduction.

[0111] The content of the above-described glycol monoether A is preferably more than the content of the above-described glycol monoether B by 0.5% by mass or more, more preferably by 1% by mass or more, further preferably by 3% by mass or more, more further preferably by 5% by mass or more, particularly preferably by 7% by mass or more, and more particularly preferably by 9% by mass or more, relative to the total amount of the ink composition. The upper limit is not particularly limited, and for example, the content of the above-described glycol monoether A is preferably more than the content of the above-described glycol monoether B by 50% by mass or less, more preferably by 40% by mass or less, further preferably by 30% by mass or less, more further preferably by 25% by mass or less, particularly preferably by 20% by mass or less, and more particularly preferably by 15% by mass or less. When the content relationship is as described above, there is a tendency to obtain higher glossiness and good unevenness reduction.

[0112] The content of the above-described glycol monoether A is preferably more than the content of the above-described glycol monoether B by 0.5% by mass or more, more preferably by 1% by mass or more, further preferably by 3% by mass or more, more further preferably by 5% by mass or more, particularly preferably by 7% by mass or more, and more particularly preferably by 9% by mass or more, relative to the total amount of the ink composition. The upper limit is not particularly limited, and for example, the content of the above-described glycol monoether A is preferably more than the content of the above-described glycol monoether B by 50% by mass or less, more preferably by 40% by mass or less, further preferably by 30% by mass or less, more further preferably by 25% by mass or less, particularly preferably by 20% by mass or less, and more particularly preferably by 15% by mass or less. When the content relationship is as described above, there is a tendency to obtain higher glossiness and good unevenness reduction.

[0113] 1.3 Other solvents

[0114] 1.3.1 Glycol diether

[0115] The non-aqueous inkjet ink composition according to the present embodiment preferably further contains a glycol diether represented by the following formula (2).

[0116] R3O-(R4O) m -R5……Equation (2)

[0117] In formula (2), R3 and R5 are alkyl groups with 1 to 4 carbon atoms, R4 is an alkylene group with 2 to 3 carbon atoms, and m is an integer from 1 to 4.

[0118] In formula (2) above, R3, R4, and R5 can be branched or linear. Examples of R3 and R5 include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, etc. Examples of R4 include ethylene (dimethylene) and propylene (trimethylene or methyl ethylene).

[0119] The aforementioned glycol diethers exhibit moderate drying properties and minimal impact on recording media. Therefore, by incorporating these glycol diethers, there is a tendency to achieve higher gloss and better unevenness reduction. Furthermore, these glycol diethers readily ensure the stability of intermittent printing when ink is ejected using inkjet printing methods, and are also advantageous in terms of low odor.

[0120] The flash point of the above-mentioned glycol diether is not particularly limited, but is preferably above 50°C, more preferably above 60°C, even more preferably above 65°C, and particularly preferably above 70°C.

[0121] The specific compounds used as the aforementioned diol diethers are not particularly limited, and examples include: diethyl glycol (35°C), diethylene glycol (-6°C), diethylene glycol methyl ethyl ether (63°C), diethylene glycol (56°C), diethylene glycol (DEDG, 71°C), dipropylene glycol (65°C), and dipropylene glycol (6.5°C) (flash points are in parentheses). A single diol diether may be used alone, or two or more may be used in combination. Among these, diethylene glycol (2) is preferred as the diol diether represented by the above formula.

[0122] The content of the glycol diether represented by the above formula (2) is preferably 35 to 75% by mass relative to the total amount of the ink composition, more preferably 45 to 70% by mass, further preferably 50 to 70% by mass, and particularly preferably 55 to 70% by mass. When the content of the glycol diether represented by the above formula (2) is within the above range, there is a tendency to obtain better gloss and unevenness reduction.

[0123] 1.3.2 Cyclic esters

[0124] The non-aqueous inkjet ink composition according to the present embodiment preferably further contains a cyclic ester. The cyclic ester has high affinity with the surface of a recording medium (e.g., a vinyl chloride-based resin), and thus can further improve the adhesiveness of the ink to the recording medium. Thereby, an image having more excellent rub fastness can be obtained. On the other hand, in the case where a cyclic ester is contained, swelling easily causes unevenness on the surface of the recording medium, and easily reduces the glossiness. However, according to the non-aqueous inkjet ink composition according to the present embodiment, even in the case where a cyclic ester is contained, the recording medium is less likely to have unevenness due to swelling, and thus the glossiness is maintained to be good.

[0125] The cyclic ester refers to a compound having a structure in which a hydroxyl group and a carboxyl group in one molecule are dehydrated and condensed with each other. The cyclic ester refers to a compound having a heterocycle including two or more carbon atoms and one oxygen atom, and a carbonyl group is disposed adjacent to the oxygen atom forming the heterocycle.

[0126] As the cyclic ester, for example, γ-butyrolactone (GBL), γ-valerolactone, γ-hexalactone, γ-heptalactone, γ-octalactone, γ-nonalactone, γ-decalactone, γ-undecalactone, δ-valerolactone, δ-hexalactone, δ-heptalactone, δ-octalactone, δ-nonalactone, δ-decalactone, δ-undecalactone, ε-caprolactam, and the like can be exemplified. Note that the number of ring members of the heterocycle of the cyclic ester is not particularly limited, and for example, any side chain can be bonded to the ring member of the heterocycle. The cyclic ester can be used alone or two or more kinds can be used in combination.

[0127] Among the cyclic esters exemplified above, a cyclic ester having 3 or more ring members and 7 or less ring members is preferable, and a cyclic ester having a 5-membered ring or a 6-membered ring is more preferable, and in any case, a cyclic ester having no side chain is more preferable. As specific examples of such a cyclic ester, γ-butyrolactone and δ-valerolactone can be exemplified.

[0128] In the case where a cyclic ester is contained, the content of the cyclic ester with respect to the total amount of the ink composition is preferably 1 to 15% by mass, more preferably 2 to 10% by mass, and further preferably 3 to 8% by mass. When the content of the cyclic ester is within the above range, there is a tendency to obtain good glossiness while maintaining appropriate adhesiveness.

[0129] 1.3.3 Others

[0130] The non-aqueous inkjet ink composition according to the present embodiment can contain, as a solvent other than the above, for example, an alcohol, a ketone, a carboxylic acid ester, an ether, an alkane diol, a polyol, an amine, or the like.

[0131] As the alcohol, for example, methanol, ethanol, propanol, butanol, isopropanol, a fluorinated alcohol, and the like can be exemplified.

[0132] As ketones, for example, acetone, methyl ethyl ketone, cyclohexanone, etc. can be mentioned.

[0133] As carboxylic acid esters, for example, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, etc. can be mentioned.

[0134] As ethers, for example, diethyl ether, dipropyl ether, tetrahydrofuran, dioxane, etc. can be mentioned.

[0135] As alkanediols, for example, ethylene glycol (alias: ethane-1, 2-diol), propylene glycol (alias: propane-1, 2-diol), 1, 2-butanediol, 1, 2-pentanediol, 1, 2-hexanediol, 1, 2-octanediol, 1, 3-propanediol, 1, 3-butanediol, 1, 4-butanediol, 2, 3-butanediol, 1, 2-pentanediol, 1, 5-pentanediol, 2, 4-pentanediol, 2-methyl-1, 3-propanediol, 3-methyl-1, 3-butanediol, 3-methyl-1, 5-pentanediol, 2-ethyl-1, 3-hexanediol, 2-methyl-1, 3-pentanediol, 3-methyl-1, 5-pentanediol, 2-methylpentane-2, 4-diol, 1, 6-hexanediol, 2-ethyl-2-methyl-1, 3-propanediol, 2-methyl-2-propyl-1, 3-propanediol, etc. can be mentioned.

[0136] As polyols, for example, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, butanediol, 1, 2, 6-hexanetriol, thioethylene glycol, hexanediol, glycerol, trimethylol ethane, trimethylol propane, etc. can be mentioned.

[0137] As amines, for example, triethanolamine, tripropanolamine, tributanolamine, N, N-dimethyl-2-aminoethanol, N, N-diethyl-2-aminoethanol, etc. hydroxylamines can be mentioned.

[0138] Further, as solvents, methyl laurate, isopropyl palmitate, isopropyl myristate, methyl oleate, ethyl oleate, etc. higher fatty acid esters, a dibasic acid diester of an aliphatic hydrocarbon having 2 to 8 carbon atoms (the number of carbon atoms not including the carbon of the carboxyl group) diesterified with an alkyl group having 1 to 5 carbon atoms, and an alkylamide (the substituents of the substituted amide nitrogen atom are each independently hydrogen atom, an alkyl group having 1 to 4 carbon atoms) of an aliphatic hydrocarbon having 6 to 10 carbon atoms (the number of carbon atoms not including the carbon of the carboxyl group) amidated, etc. can be mentioned.

[0139] 1.4 Resin

[0140] The non-aqueous inkjet ink composition according to the present embodiment preferably further contains an acrylic resin. The acrylic resin has a small effect on reduction in glossiness. It is presumed that this is because the floatability is improved by making the viscosity when the acrylic resin is dissolved in a solvent higher. Thus, by further containing an acrylic resin, there is a tendency that high glossiness can be maintained while the scratch resistance is improved.

[0141] As the acrylic resin, for example, poly(meth)acrylic acid, poly(meth)acrylate methyl ester, poly(meth)acrylate ethyl ester, (meth)acrylate-meth)acrylate copolymer resin, styrene-(meth)acrylic acid copolymer resin, ethylene-(meth)acrylic acid copolymer resin, ethylene alkyl(meth)acrylate resin, ethylene-(meth)acrylate copolymer resin, and the like can be exemplified.

[0142] Note that in the present specification, "(meth)acrylic acid" means acrylic acid or methacrylic acid, and "(meth)acrylate" means acrylate or methacrylate.

[0143] As the acrylic resin, commercially available products can also be used, and for example, ACRYPET MF (trade name, manufactured by Mitsubishi Rayon Co., Ltd., acrylic resin), SUMIPEX LG (trade name, manufactured by Sumitomo Chemical Co., Ltd., acrylic resin), PARALOID B series (trade name, manufactured by Dow Chemical Co., Ltd., acrylic resin) such as PARALOID B60, PARAPET G-1000P (trade name, manufactured by KURARAY Co., Ltd., acrylic resin), and the like can be exemplified.

[0144] In the case where the acrylic resin is contained, the content of the acrylic resin is preferably 0.05 to 1.00% by mass, more preferably 0.10 to 0.70% by mass, further preferably 0.15 to 0.40% by mass, and particularly preferably 0.20 to 0.30% by mass, with respect to the total mass of the ink composition. When the content of the acrylic resin is within the above range, there is a tendency that high glossiness can be more maintained, and the scratch resistance can be more improved.

[0145] The non-aqueous inkjet ink composition according to the present embodiment can further contain a resin other than the acrylic resin, and as such a resin, for example, a vinyl chloride resin, an aliphatic polyester, an aromatic polyester, a polyurethane, an epoxy resin, a polyvinyl acetate, an ethylene-vinyl acetate copolymer resin, a polycarbonate, a polyvinyl butyral, a polyvinyl alcohol, a phenoxy resin, an ethyl cellulose resin, a cellulose acetate propionate resin, a cellulose acetate butyrate, a nitrocellulose resin, a polystyrene, a vinyltoluene-α-methylstyrene copolymer resin, a polyamide, a polyimide, a polysulfone resin, a petroleum resin, a chlorinated polypropylene, a polyolefin, a terpene resin, a rosin-modified phenol resin, various synthetic rubbers such as NBR, SBR, MBR, and modified products thereof, and the like can be listed. These resins can be used singly or in combination of two or more.

[0146] 1.5 Surface conditioner

[0147] The non-aqueous inkjet ink composition according to the present embodiment preferably further contains a surface conditioner. The surface conditioner has a function of improving the lubricity of the printed surface and enables the rubbing fastness to be more excellent. The surface conditioner is also referred to as a lubricant.

[0148] As the surface conditioner, a silicone-based surfactant is preferable, and a modified silicone compound such as a polyester-modified silicone, a polyether-modified silicone, and the like is more preferable. As the polyester-modified silicone, BYK-347, 348, BYK-UV 3500, 3510, 3530 (all manufactured by BYK Additives & Instruments), and the like can be listed, and as the polyether-modified silicone, BYK-333, 3570 (manufactured by BYK Additives & Instruments), and the like can be listed.

[0149] In the case where the surface conditioner is contained, the content of the surface conditioner is preferably 0.01 to 1.00% by mass, more preferably 0.01 to 0.50% by mass, further preferably 0.01 to 0.20% by mass, more further preferably 0.02 to 0.10% by mass, particularly preferably 0.03 to 0.08% by mass, and more particularly preferably 0.03 to 0.07% by mass, relative to the total mass of the ink composition. When the content of the surface conditioner is within the above range, the rubbing fastness tends to be more excellent.

[0150] 1.6 Dispersant

[0151] The non-aqueous inkjet ink composition according to the present embodiment can further contain a dispersant for dispersing a lustrous pigment. The dispersant is not particularly limited, and for example, an anionic dispersant, a nonionic dispersant, a high-molecular dispersant, and the like can be listed.

[0152] As the anionic dispersant, there are no particular limitations, and examples include formalin condensates of aromatic sulfonic acids, formalin condensates of β-naphthalenesulfonic acids, formalin condensates of alkyl naphthalene sulfonic acids, and formalin condensates of creosote sulfonic acids.

[0153] As the aromatic sulfonic acid, there are no particular limitations, and examples include creosote sulfonic acid, cresol sulfonic acid, phenol sulfonic acid, β-naphthol sulfonic acid, alkyl naphthalene sulfonic acids such as methyl naphthalene sulfonic acid and butyl naphthalene sulfonic acid, a mixture of β-naphthalenesulfonic acid and β-naphthol sulfonic acid, a mixture of cresol sulfonic acid and 2-naphthol-6-sulfonic acid, and lignin sulfonic acid.

[0154] As the nonionic dispersant, there are no particular limitations, and examples include ethylene oxide adducts of phytosterols, ethylene oxide adducts of cholestanols, and the like.

[0155] As the high-molecular dispersant, there are no particular limitations, and examples include polyoxyalkylene amine compounds, polyalkyl acrylate partial esters, polyalkylene polyamines, polyacrylate salts, styrene-acrylic acid copolymers, vinyl naphthalene-maleic acid copolymers, and the like. As commercially available products of polyoxyalkylene amine compounds, there are, for example, JEFFAMIN M2070 (manufactured by HUNTSMAN), GENAMIN (M41 / 2000) (manufactured by Clariant), and the like.

[0156] 1.7 Other Components

[0157] The non-aqueous inkjet ink composition according to the present embodiment can also be appropriately added with various additives, such as surfactants, co-solvents, viscosity adjustors, pH adjustors, antioxidants, preservatives, antifungal agents, corrosion inhibitors, and chelating agents for capturing metal ions that can affect dispersion.

[0158] 2. Recording Method

[0159] The recording method according to one embodiment of the present application includes a step of ejecting the non-aqueous inkjet ink composition described above by an inkjet method and causing it to adhere to a recording medium (ink adhering step).

[0160] According to the recording method according to the present embodiment, since the non-aqueous inkjet ink composition described above is used, which is capable of maintaining a moderate adhesiveness of the recording medium to the ink, reducing unevenness due to swelling of the recording medium, and appropriately adjusting the drying speed of the ink, an image having high glossiness and good reduction in unevenness can be printed.

[0161] 2.1 Ink Adhering Step

[0162] The ink adhering step is a step of adhering the above non-aqueous inkjet ink composition to a recording medium using an inkjet method. The ink composition ejection using the inkjet method can be performed using a publicly known inkjet recording apparatus. As the ejection method, a piezoelectric method, a method of ejecting ink by generating bubbles by heating the ink, and the like can be used.

[0163] Recording medium

[0164] The recording medium is not particularly limited, and examples include an absorbent recording medium, a low-absorbent recording medium, and a non-absorbent recording medium. Among them, as the use of the non-aqueous ink, a low-absorbent recording medium and a non-absorbent recording medium are preferable.

[0165] The absorbent recording medium is not particularly limited, and examples include ordinary paper such as electrophotographic paper having high permeability of the ink composition, inkjet paper (inkjet paper having an ink absorbing layer composed of silica particles or alumina particles, or an ink absorbing layer composed of a hydrophilic polymer such as polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP)), and a recording medium having a support composed of paper.

[0166] The ink low-absorbent or non-absorbent recording medium refers to a recording medium having a property of not absorbing the ink composition at all or hardly absorbing the ink composition. Quantitatively, the ink non-absorbent or low-absorbent recording medium refers to a recording medium having a water absorption amount of 10 mL / m2 1 / 2 or less in the Bristow method from the start of contact to 30 msec 2 . The Bristow method is the most popular method for measuring the liquid absorption amount in a short time, and is adopted by the Japan Technical Association of the Pulp and Paper Industry (JAPAN TAPPI). The details of the test method are described in the specification No. 51 "Paper and Board - Test Methods for Liquid Absorption - Bristow Method" of "JAPAN TAPPI Test Methods for Pulp and Paper 2000 Edition". In contrast, the ink-absorbent recording medium means a recording medium not belonging to the ink non-absorbent and low-absorbent recording medium.

[0167] The ink non-absorbent recording medium can include, for example, a medium having a plastic film coated on a substrate such as a plastic film, paper, and the like, and a medium having a plastic film adhered. As the plastic described herein, polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene, and the like can be used.

[0168] In addition, as the recording medium having low ink absorbency, a recording medium having a coating layer for receiving ink on the surface thereof can be exemplified, for example, as a medium having paper as a base material, art paper, bristol board, matte paper, and the like can be exemplified, and in the case where a plastic film is used as the base material, a medium having a hydrophilic polymer coated on the surface of polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene, and the like, and a medium having an adhesive coated on the surface thereof together with particles of silica, titanium, and the like can be exemplified.

[0169] Further, in addition to the above-described recording medium, a plate material of a metal such as iron, silver, copper, and aluminum, a recording medium of glass, and the like having no or low ink absorbency can be used.

[0170] 2.2 Other processes

[0171] Coloring ink adhering process

[0172] The recording method according to the present embodiment can have a process of ejecting a coloring ink composition containing a color material by an inkjet method and adhering the same to a recording medium (coloring ink adhering process).

[0173] The order of the above-described ink adhering process and the coloring ink adhering process is not particularly limited, and the coloring ink adhering process is preferably performed after the ink adhering process. In addition, the above-described non-aqueous inkjet ink composition and the coloring ink composition can be adhered to different parts of the recording medium, or can be overlapped and adhered to the same part, and the latter is preferable.

[0174] The coloring ink composition contains a color material instead of a luster pigment, and the components and the composition thereof can be the same as those of the above-described non-aqueous inkjet ink composition.

[0175] The coloring ink composition contains a color material. As the color material, pigments and dyes can be exemplified. As the pigments, inorganic pigments and organic pigments can be used. As the dyes, acid dyes, reactive dyes, direct dyes, and the like can be exemplified. Note that the color material does not include the above-described luster pigment.

[0176] The inorganic pigments are not particularly limited, and carbon black such as furnace black, lamp black, acetylene black, and channel black; white inorganic oxides such as iron oxide, titanium oxide, and zinc oxide; and silicon dioxide can be exemplified.

[0177] As carbon blacks, for example, C.I. (Colour Index Generic Name) Pigment Black 1, 7, 11, etc. can be given. Commercially available products can be used as carbon blacks, for example, No. 2300, No. 900, MCF88, No. 33, No. 40, No. 45, No. 52, MA7, MA8, MA100, No. 2200B, etc. of Mitsubishi Chemical Corporation, Raven (registered trademark) 5750, 5250, 5000, 3500, 1255, 700, etc. of Columbia carbon, Regal (registered trademark) 400R, 330R, 660R, Mogul (registered trademark) L, Monarch (registered trademark) 700, 800, 880, 900, 1000, 1100, 1300, 1400, etc. of CABOT, Pigment Black FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Printex (registered trademark) 35, U, V, 140U, Special Black 6, 5, 4A, 4, etc. of Degussa can be given.

[0178] As organic pigments, for example, quinacridone pigments, quinacridonequinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, anthanthrone pigments, indathrene pigments, flavanthrone pigments, perylene pigments, diketopyrrolopyrrole pigments, perinone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments, isoindolinone pigments, azomethine pigments, or azo pigments, etc. can be given.

[0179] As specific examples of organic pigments, the following substances can be given.

[0180] As cyan pigments, for example, C.I. Pigment Blue 1, 2, 3, 15:3, 15:4, 15:34, 16, 22, 60, etc. can be given. C.I. Vat Blue 4, 60, etc. can be given, and preferably, for example, one or two or more kinds selected from the group consisting of C.I. Pigment Blue 15:3, 15:4, and 60 can be given.

[0181] As magenta pigments, for example, C.I. Pigment Red 5, 7, 12, 48(Ca), 48(Mn), 57(Ca), 57:1, 112, 122, 123, 168, 184, 202, C.I. Pigment Violet 19, etc. can be given. Preferably, for example, one or two or more kinds selected from the group consisting of C.I. Pigment Red 122, 202, and 209, C.I. Pigment Violet 19 can be given.

[0182] As yellow pigments, C.I. 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. can be exemplified, and preferably, one or two or more kinds selected from the group consisting of C.I. Pigment Yellow 74, 109, 110, 128, 138, 150, and 180 can be exemplified.

[0183] Other pigments can also be used. For example, orange pigments, green pigments, etc. can be exemplified.

[0184] The pigments can be used alone or in combination with two or more kinds.

[0185] Note that, in order to improve the dispersibility of the pigments in the colored ink composition, it is preferable to apply a surface treatment or incorporate a dispersant, etc. to the pigments.

[0186] Note that, the colored ink composition and the above-described non-aqueous inkjet ink composition can be manufactured into an ink set for recording. The "ink set" refers to two or more inks for recording in a set. The respective inks possessed by the ink set can be housed in separate ink containers, or can be housed in an integrated ink container. The ink set possesses at least one (one kind) of the above-described non-aqueous inkjet ink composition and at least one (one kind) of the colored ink composition.

[0187] Primary heating step

[0188] The recording method according to the present embodiment can possess a primary heating step, that is, a step of heating the ink composition adhered to the recording medium at an early stage.

[0189] The primary heating step is a step of heating the ink adhered to the recording medium at an early stage to dry it. The primary heating step is a heating step for drying at least a part of the liquid medium in the ink adhered to the recording medium to at least reduce the flow of the ink.

[0190] The primary heating step can be performed after the ink is adhered to the recording medium, or can be performed at an early stage after the ink is adhered. The ink droplet dropped on the recording medium is preferably heated within 0.5 seconds after the ink droplet is dropped.

[0191] The primary heating step is preferably an IR heater, a microwave radiator, a platen heater, or a hot air blower to the recording medium by a fan.

[0192] The heating in the one-time heating step can be performed at least any of before the ink adhering step, simultaneously with the adhering, and in the early stage after the adhering, and is preferably performed simultaneously. The ink adhering step can be performed by such a heating sequence. In particular, the recording medium is preferably heated, and the ink composition is adhered to the heated recording medium by the ink adhering step.

[0193] In the case of having the one-time heating step, the ink composition can be dried quickly on the recording medium, and thus bleeding of the ink can be prevented, and thus is preferable. On the other hand, in the case of having the one-time heating step, the ink is dried quickly, and thus the time for floating of the light-shining pigment is sometimes not sufficiently ensured, and thus the gloss is sometimes poor; or the ejection stability is sometimes deteriorated after receiving the heat of the one-time heating step. However, according to the recording method according to the present embodiment, by using the above-described non-aqueous inkjet ink composition, even in the case of performing the one-time heating step, excellent gloss and ejection stability can be obtained, and thus is preferable.

[0194] The surface temperature of the recording surface of the recording medium in the one-time heating step of heating the ink composition is preferably 30°C or higher. On the other hand, it is preferably 60°C or lower. It is more preferably 35°C or higher and 55°C or lower, and even more preferably 40°C or higher and 50°C or lower. When the surface temperature of the recording medium is the above-described range, bleeding prevention and ejection stability are more excellent, and thus is preferable. Note that the surface temperature of the recording medium in the one-time heating step is the surface temperature of the recording medium at the time of adhering the ink or the temperature of the recording medium at the time of heating after the adhering. In addition, it is also the maximum temperature during recording.

[0195] Post-heating step

[0196] The recording method according to the present embodiment can further have a post-heating step (two-time heating step) of heating the recording medium after the ink adhering step.

[0197] The post-heating step refers to a heating step of heating sufficiently to a degree at which recording is completed and the recorded matter can be used. The post-heating step is a heating step for sufficiently drying the solvent component of the ink.

[0198] The post-heating step is preferably started after 0.5 seconds or more from the start of the adhering of the ink to the recording medium. For example, it is preferably started after 0.5 seconds or more from the start of the adhering of the ink to a certain recording region of the recording medium, and heating is started for the region.

[0199] The heating of the recording medium in the post-heating step can be performed using, for example, a suitable heating device. The surface temperature of the recording medium at this time is preferably 50°C or higher, and more preferably 60°C or higher, 70°C or higher, or 75°C or higher. The upper limit is not limited, but is preferably 120°C or lower. In addition, the temperature of the heating is preferably lower than the softening point of the substrate of the recording medium.

[0200] 2.3 Recording device

[0201] Hereinafter, one example of a recording device which can be preferably used for the recording method related to the present embodiment will be described with reference to the drawings.

[0202] Summary of device configuration

[0203] Figure 1 is a schematic cross-sectional view schematically showing a recording device. As shown in the figure, an inkjet recording device 1 is provided with a recording head 2, an IR heater 3, a platen 4, a heater 5, a cooling fan 6, a pre-heater 7, and an air exchange fan 8. In addition, the recording head is mounted on a carriage not shown in the figure, and performs main scanning in the inboard-fore direction of the figure, and attaches ink to a recording medium M. In addition, the platen 4 is provided with a platen heater not shown in the figure. The inkjet recording device 1 is provided with a control section not shown in the figure, and controls each part to perform recording. In addition, the recording head 2 receives ink supply from an ink container not shown in the figure. Figure 1

[0204] Configuration related to inkjet head

[0205] The recording head 2 as an inkjet head is configured to perform recording on a recording medium M by ejecting and attaching an ink composition from a nozzle of the recording head 2. Figure 1 The recording head 2 shown in the figure is a serial type recording head, and is used to attach ink to a recording medium M by relatively scanning the recording medium M in a main scanning direction multiple times. The recording head 2 is mounted on a carriage not shown in the figure. The recording head 2 relatively scans the recording medium M in the main scanning direction multiple times by the action of a carriage moving mechanism which moves the carriage in a medium width direction of the recording medium M (inboard-fore direction of the figure). The medium width direction is the main scanning direction of the recording head 2. The scanning in the main scanning direction is also referred to as main scanning.

[0206] In addition, here, the main scanning direction is the moving direction of the carriage on which the recording head 2 is mounted. In the present embodiment, the main scanning direction is a direction intersecting with a conveyance direction of the recording medium M, i.e., a sub scanning direction, shown by an arrow SS. Also, the recording medium M is recorded by repeatedly performing main scanning of the recording head 2 and conveyance of the recording medium M, i.e., sub scanning, multiple times. Figure 1

[0207] The ejection of the recording head 2 can use a publicly known method. For example, a method of using vibration of a piezoelectric element to eject a liquid droplet, i.e., a method of forming an ink droplet by mechanical deformation of an electrostrictive element.

[0208] Primary heating mechanism

[0209] ​​The inkjet recording apparatus 1 can have a first heating mechanism that performs a first heating process that heats the recording medium M when the ink is ejected from the recording head 2 and adhered to the recording medium. The first heating mechanism can employ a conduction type, a blowing type, a radiation type, or the like. The conduction type conducts heat from a member that contacts the recording medium to the recording medium. Examples include a platen heater. Note that the platen heater is not shown in the drawing and is provided integrally with the platen 4. The blowing type blows normal temperature air or hot air to the recording medium to dry the ink. Examples include a blowing fan. The radiation type heats the recording medium by emitting a ray that generates heat to the recording medium. Examples include an IR radiator. In addition, a heater identical to the platen heater is provided on the side of the platen 4 that is located immediately downstream in the SS direction, which is not shown in the drawing. These first heating mechanisms can be used alone or in combination.

[0210] For example, as the first heating mechanism, the IR radiator 3 and the platen heater are provided.

[0211] Note that when the IR radiator 3 is used, the recording medium M can be heated by radiating infrared rays from the side of the recording head 2. Thus, the recording head 2 is also easily heated at the same time, but the temperature can be raised without being affected by the thickness of the recording medium M, compared to the case where the platen heater or the like heats from the back of the recording medium M. Note that the first heating mechanism can also have various fans (e.g., a ventilation fan 8) that blow hot air or air at the same temperature as the environment to the recording medium M to dry the ink on the recording medium M.

[0212] The platen heater can heat the recording medium M via the platen 4 at a position opposite the recording head 2. The platen heater can heat the recording medium M in a conduction type, which is used as needed in the inkjet recording method.

[0213] In addition, the inkjet recording apparatus 1 can also have a pre-heater 7 that preheats the recording medium M before the ink is adhered to the recording medium M.

[0214] Post-heating mechanism

[0215] The inkjet recording apparatus 1 can also have a post-heating mechanism that performs a post-heating process that heats the recording medium after the ink adhering process to dry and fix the ink.

[0216] The heater 5 for the post-heating mechanism is used to dry and cure the ink adhered to the recording medium M. The heater 5 can cause the solvent or the like contained in the ink to evaporate and disperse more quickly by heating the recording medium M after the recording image is formed. In this way, the recorded matter can be obtained in a shorter time.

[0217] Other configurations

[0218] The inkjet recording apparatus 1 can also have a cooling fan 6. After the ink recorded on the recording medium M is dried, the ink on the recording medium M is cooled by the cooling fan 6, whereby the ink coating film can be formed on the recording medium M with good adhesion.

[0219] Figure 1 The recording apparatus shown is a serial printer that records by the so-called serial method. The recording apparatus can also be a line printer that has a line head and records by the line method.

[0220] The line head has a nozzle row in which a plurality of nozzles are arranged in the width direction of the recording medium, and has a length that is greater than or equal to the width of the recording medium M being conveyed, and can record an image on the recording medium M being conveyed in the width direction of the recording medium at one time. Also, recording can be performed by one scan. Or it can be recorded as follows: after one scan is performed while the recording medium is being conveyed, the recording medium is returned in the opposite direction to the conveying direction, and then conveyed again and scanned again, whereby two or more scans are performed.

[0221] Note that the recording medium being conveyed can be scanned by a head that is fixed in position, or the recording medium that is fixed in the platen area can be scanned by a head that is moving.

[0222] Note that the recording apparatus that records by the line method can be the same as the one shown in Figure 1 except that the recording head 2 is changed to a line head. Specifically, the same heating mechanisms as those shown in Figure 1 above the recording head 2, the IR heater 3, the platen heater, the preheater 7, and the like can be provided above or below the line head. Also, the heater 5 as the post-heating mechanism, the cooling fan 6, and the like shown in Figure 1 above can be provided.

[0223] 3. Example

[0224] Hereinafter, the present application will be described more specifically by examples, but the present application is not limited by these examples. Unless otherwise specified, the following "%" is a mass standard.

[0225] 3.1 Production of Non-aqueous Inkjet Ink Composition

[0226] Each component was charged into a container so as to become the composition of Table 1 and Table 2 below, mixed and stirred sufficiently, and a non-aqueous inkjet ink composition relating to each example and each comparative example was obtained. Note that the values relating to the composition of Table 1 and Table 2 below are in mass %, and the total is 100.0 mass %. In addition, the lightness pigment is a solid content value, and a pigment dispersion liquid that was produced in advance by the following method was used.

[0227] Method for producing pigment dispersion liquid

[0228] First, a polyethylene terephthalate film having a surface roughness Ra of 0.02 μm or less and a smooth surface was prepared. Next, an acetone-soluble release resin was applied to one side of the film as a whole by a roll coater, thereby forming a release layer. The polyethylene terephthalate film on which the release layer was formed was transported into a vacuum deposition device at a speed of 5 m / s, and a film composed of Al having a thickness of 15 nm was formed under reduced pressure. Next, the polyethylene terephthalate film on which the Al film was formed was immersed in tetrahydrofuran, and ultrasonic vibration at 40 kHz was imparted, thereby obtaining a dispersion liquid of a metal powder which was an aggregate of Al metal particles.

[0229] Tetrahydrofuran was removed by a centrifugal separator, and diethylene glycol diethyl ether (DEDG) was added, thereby obtaining a suspension liquid in which the content of the metal powder was 5 mass%. Next, the suspension liquid was subjected to treatment by a circulating high-output ultrasonic disintegrator, and the metal particles were disintegrated to a particle diameter of 0.5 μm. In this treatment, ultrasonic vibration at 20 kHz was imparted.

[0230] Next, an amine-based dispersant (JEFFAMIN M2070) was added to the suspension liquid, and the metal particles were pre-dispersed.

[0231] Further, phosphoric acid monostearyl ester as an alkyl phosphate was added as a surface treatment agent. Next, ultrasonic vibration at 40 kHz was applied for 1 hour, and additional dispersion was performed, and coarse particles were removed by filtration with a filter, thereby obtaining a metal pigment dispersion liquid.

[0232] Table 1

[0233]

[0234] Table 2

[0235]

[0236] The above description of Tables 1 and 2 is supplemented.

[0237] Composition

[0238] Bright pigment

[0239] The volume average particle diameter (D50) was 0.5 μm, and the average thickness was 15 nm. Note that the volume average particle diameter (D50) was measured using a MICROTRAC MT-3300 (manufactured by Microtrac Bell, a laser diffraction / scattering type particle diameter distribution measuring device). In addition, the average thickness was measured by atomic force microscope method using a NanoNavi E-Sweep (manufactured by SII NanoTechnology), and measurement was performed on any 50 metal pigments and the average value was taken.

[0240] Glycol monoether A

[0241] • MFDG (dipropylene glycol monomethyl ether, normal boiling point 189.6°C, surface tension 28.8 mN / m)

[0242] • BPG (propylene glycol monobutyl ether, normal boiling point 170.2°C, surface tension 26.8 mN / m)

[0243] • BMG (methylene glycol monobutyl ether, normal boiling point 171°C, surface tension 26.5 mN / m)

[0244] • MMB (3-methoxy-3-methylbutanol, normal boiling point 174°C, surface tension 29.9 mN / m)

[0245] Glycol monoether B

[0246] • BTGH (tetraethylene glycol monobutyl ether, normal boiling point 290°C, surface tension 34.5 mN / m)

[0247] • MtetG (tetraethylene glycol monomethyl ether, normal boiling point 285°C, surface tension 34.7 mN / m)

[0248] • MFTG (tripropylene glycol monomethyl ether, normal boiling point 271°C, surface tension 30.8 mN / m)

[0249] • EHDG (diethylene glycol ethylhexyl ether, normal boiling point 302°C, surface tension 31.7 mN / m)

[0250] • PhDG (dipropylene glycol phenyl ether, normal boiling point 309°C, surface tension 40.1 mN / m)

[0251] • MTG (triethylene glycol monomethyl ether, normal boiling point 233.9°C, surface tension 33.4 mN / m)

[0252] Others

[0253] • GBL (γ-butyrolactone, normal boiling point 200°C, surface tension 41 mN / m)

[0254] • DEDG (diethylene glycol diethyl ether, standard boiling point 188°C, surface tension 26.9 mN / m)

[0255] • PARALOID B60 (acrylic resin, trade name of product manufactured by Dow Chemical Company)

[0256] • BYK-333 (silicon-based surface modifier, polyether-modified silicon compound, trade name of product manufactured by BYK Additives & Instruments Company)

[0257] Terms

[0258] • "Glycol monoether A" is a compound represented by the following formula (1) having a flash point of 85°C or less.

[0259] • "Glycol monoether B" is a compound represented by the following formula (1) having a flash point of 95°C or more.

[0260] R1-(O-R2) n -OH Formula (1)

[0261] In formula (1), R1is an alkyl group having 1 to 8 carbon atoms or a phenyl group, R2is an alkylene group having 1 to 5 carbon atoms, and n is an integer of 1 to 4.

[0262] • "f.p." means flash point.

[0263] • "Total content (A+B)" means the total content of glycol monoether A and glycol monoether B with respect to the total amount of the ink composition.

[0264] • "Mass ratio (A / B)" means the content ratio of the content of glycol monoether A with respect to the content of glycol monoether B.

[0265] • "20 degrees" in glossiness means the measurement of the glossiness of the 20-degree reflection of the recording surface.

[0266] • "60 degrees" in glossiness means the measurement of the glossiness of the 60-degree reflection of the recording surface.

[0267] • The temperatures of "40°C" and "50°C" in unevenness mean the temperature of the heater located in the position opposite to the inkjet head during printing.

[0268] 3.2 Recording conditions

[0269] The non-aqueous inkjet ink composition obtained in the above was filtered and degassed, then filled in an ink pack, and mounted as a metallic ink on an inkjet printer ("SC-S80650", manufactured by Seiko Epson Corporation). Also, a commercially available color ink, particularly yellow ("SC10Y70", manufactured by Seiko Epson Corporation) or light cyan ("SC10LC70", manufactured by Seiko Epson Corporation) was mounted as a colored ink composition on the above printer. A printing medium was vinyl chloride (Orajet-3165G).

[0270] As the printed image, an image data (resolution 1440 dpi) of an overlaid pattern of the metallic printing and the color printing after dataization was prepared, the metallic layer of the substrate was a pattern image of a full-face coating, and the color printing of the upper layer was a 1 cm square pattern and a 1 to 3 mm fine line, thereby obtaining a recording material. The metallic printing of the substrate used a nozzle usage rate of 70%, and the color ink of the upper layer used a pattern in which the nozzle usage rate was changed to 20 to 100%. Also, in order to judge the drying property of the ink, the printing temperature (heater temperature just below the print head) was performed at two levels of 40°C and 50°C. Among them, in the recording material for the evaluation of the glossiness, the printing temperature was 40°C.

[0271] 3.3 Evaluation method

[0272] 3.3.1 Glossiness (20 degrees)

[0273] The glossiness of the recording surface of the recording material obtained above was measured using a gloss meter MULTI Gloss 268 (manufactured by KONICA MINOLTA), and evaluated according to the following criteria.

[0274] Evaluation criteria

[0275] A: 620 or more;

[0276] B: 580 or more and less than 620;

[0277] C: less than 580.

[0278] 3.3.2 Glossiness (60 degrees)

[0279] The glossiness of the recording surface of the recording material obtained above was measured using a gloss meter MULTI Gloss 268 (manufactured by KONICA MINOLTA), and evaluated according to the following criteria.

[0280] Evaluation criteria

[0281] A: 455 or more;

[0282] B: less than 455.

[0283] 3.3.3 unevenness (40°C)

[0284] The quality of the color ink on the upper layer was observed under a microscope, and the dryness of the metallic color was evaluated according to the following criteria. Note that the difference in dryness was first apparent in a pattern of yellow ink of a bright shade formed on the metallic layer, and thus the shade of yellow and the phenomenon of coffee ring, which is a problem when the colorant dries, were determined.

[0285] Evaluation criteria

[0286] A: good, no unevenness and no darkening of yellow in all colors;

[0287] B: darkening (considered to be caused by redissolution of the metallic layer of the substrate) was observed in the color (yellow);

[0288] C: unevenness caused by darkening and the phenomenon of coffee ring were observed in the color (yellow);

[0289] D: darkening and the phenomenon of coffee ring were observed in colors other than yellow.

[0290] 3.3.4 unevenness (50°C)

[0291] The evaluation was performed in the same manner and criteria as in the above "unevenness (40°C)", except that the printing temperature was set to 50°C.

[0292] 3.4 Evaluation results

[0293] The evaluation results are shown in Tables 1 and 2 above.

[0294] Each of the non-aqueous inkjet ink compositions according to the embodiments of the present application can achieve both good glossiness and good reduction in unevenness. In contrast, in each of the comparative examples other than the present application, at least one of the glossiness and the unevenness is poor.

[0295] The following is derived from the above-described embodiments.

[0296] One aspect of the non-aqueous inkjet ink composition contains a luster pigment, and diol monoethers A and B represented by the following formula (1) that differ from each other in flash point,

[0297] The flash point of the diol monoether A is 85°C or lower,

[0298] The flash point of the diol monoether B is 95°C or higher,

[0299] The total content of the diol monoether A and the diol monoether B is 20 to 60 mass% relative to the total amount of the ink composition.

[0300] The content of the diol monoether A is more than the content of the diol monoether B.

[0301] R1-(O-R2) n -OH … Formula (1)

[0302] In Formula (1), R1is an alkyl group having 1 to 8 carbon atoms or a phenyl group, R2is an alkylene group having 1 to 5 carbon atoms, and n is an integer of 1 to 4.

[0303] In one aspect of the non-aqueous inkjet ink composition described above,

[0304] In the diol monoether A, R2of Formula (1) can be an alkylene group having 3 carbon atoms.

[0305] In any of the aspects of the non-aqueous inkjet ink composition described above,

[0306] The diol monoether B can be tetraethylene glycol monobutyl ether.

[0307] In any of the aspects of the non-aqueous inkjet ink composition described above,

[0308] The non-aqueous inkjet ink composition described above can further contain an acrylic resin.

[0309] In any of the aspects of the non-aqueous inkjet ink composition described above,

[0310] The lustrous pigment can be surface-treated with an alkyl phosphate.

[0311] In any of the aspects of the non-aqueous inkjet ink composition described above,

[0312] The non-aqueous inkjet ink composition described above can further contain a diol diether represented by the following Formula (2).

[0313] R3O-(R4O) m -R5 … Formula (2)

[0314] In Formula (2), R3and R5are each independently an alkyl group having 1 to 4 carbon atoms, R4is an alkylene group having 2 to 3 carbon atoms, and m is an integer of 1 to 4.

[0315] In any of the aspects of the non-aqueous inkjet ink composition described above,

[0316] The content of the diol monoether A can be 15 to 55 mass% relative to the total amount of the ink composition.

[0317] In any of the aspects of the non-aqueous inkjet ink composition described above,

[0318] The content of the diol monoether B can be 5 to 15 mass% relative to the total amount of the ink composition.

[0319] In any of the above-described non-aqueous inkjet ink composition,

[0320] The content (A / B) of the diol monoether A relative to the content of the diol monoether B can be 1.8 or more in terms of mass ratio.

[0321] One aspect of the recording method includes a step of ejecting the non-aqueous inkjet ink composition of any of the above-described aspects by an inkjet method and adhering it to a recording medium.

[0322] The present application is not limited to the above-described embodiments and can have various modifications. For example, the present application includes a configuration substantially the same as the configuration described in the embodiments, for example, a configuration having the same function, method, and result, or a configuration having the same purpose and effect. In addition, the present application also includes a configuration in which a non-essential part of the configuration described in the embodiments is replaced. In addition, the present application also includes a configuration that can achieve the same effects as the configuration described in the embodiments or a configuration that achieves the same purpose. In addition, the present application also includes a configuration in which a publicly known technology is added to the configuration described in the embodiments.

Claims

1. A non-aqueous inkjet ink composition, characterized by comprising: contains a bright pigment, and a diol monoether A and a diol monoether B represented by the following formula (1) having different flash points from each other, the flash point of the diol monoether A is 50°C or higher and 85°C or lower, the flash point of the diol monoether B is 95°C or higher, the total content of the diol monoether A and the diol monoether B is 20% by mass to 60% by mass with respect to the total amount of the ink composition, the content of the diol monoether A is more than the content of the diol monoether B, R1-(O-R2) n -OH …… Formula (1) in formula (1), R1 is an alkyl group having 1 to 8 carbon atoms or a phenyl group, R2 is an alkylene group having 1 to 5 carbon atoms, n is an integer of 1 to 4 when the diol monoether A is the diol monoether A, and n is an integer of 2 to 4 when the diol monoether B is the diol monoether B.

2. The non-aqueous inkjet ink composition according to claim 1, characterized in that, in the diol monoether A, R2 of formula (1) is an alkylene group having 3 carbon atoms.

3. The non-aqueous inkjet ink composition according to claim 1 or claim 2, characterized in that, the diol monoether B is tetraethylene glycol monobutyl ether.

4. The non-aqueous inkjet ink composition according to claim 1, characterized in that, the non-aqueous inkjet ink composition further contains an acrylic resin.

5. The non-aqueous inkjet ink composition according to claim 1, characterized in that, the bright pigment is surface-treated with an alkyl phosphate.

6. The non-aqueous inkjet ink composition according to claim 1, characterized in that, the non-aqueous inkjet ink composition further contains a diol diether represented by the following formula (2), R3O-(R4O) m -R5 Formula (2) in formula (2), R3 and R5 are each independently an alkyl group having 1 to 4 carbon atoms, R4 is an alkylene group having 2 to 3 carbon atoms, and m is an integer of 1 to 4.

7. The non-aqueous inkjet ink composition according to claim 1, characterized in that, the content of the diol monoether A is 15% by mass to 55% by mass with respect to the total amount of the ink composition.

8. The non-aqueous inkjet ink composition according to claim 1, characterized in that, the content of the diol monoether B is 5% by mass to 15% by mass with respect to the total amount of the ink composition.

9. The non-aqueous inkjet ink composition according to claim 1, characterized in that, the content of the diol monoether A with respect to the content of the diol monoether B A / B is 1.8 or higher in mass ratio.

10. A recording method characterized by, a process of ejecting the non-aqueous inkjet ink composition according to any one of claims 1 to 9 by an inkjet method and adhering it to a recording medium.

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