Recording method and recording device

Abstract

To provide a recording method which is good in discharge stability of an ink composition and can obtain a recorded matter having excellent metallic gloss.SOLUTION: There is provided a recording method which comprises: an adhering step of adhering an ink composition to a recording medium by discharging the ink composition from an inkjet head; and a first heating step of heating the recording medium in the adhering step, wherein the adhering step has a step in which the discharge frequency of the ink composition is 15 kHz or more, the ink composition comprising a metallic pigment and a solvent component, the solvent component containing an organic solvent, the metallic pigment being scaly and metal particles, the surface of which is treated with a compound represented by the following formula (1) or the following formula (2). (R1-)P(O)(OH)2...(1), and (R2-O-)aP(O)(OH)3-a...(2), wherein, R1 and R2 each independently represent a hydrocarbon group having 14 or more carbon atoms which may be substituted with a substituent, and a represents 1 or 2.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a recording method and a recording apparatus. [Background technology]

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

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-172862 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, in some cases, the ink composition is applied to the recording medium while heating it, for purposes such as accelerating the drying of the recorded material and improving image quality. Furthermore, in order to perform high-resolution recording at high speed, the ink ejection frequency may be increased to record images with smaller ink droplets and efficiently obtain high-resolution images. When such a primary heating process is performed and the ink droplet ejection frequency is high, ejection stability may be poor.

[0005] Therefore, there is a need for a recording method that can produce recordings with good ink composition ejection stability and excellent metallic luster. [Means for solving the problem]

[0006] One aspect of the recording method according to the present invention is: An adhesion process in which the ink composition is ejected from the inkjet head and attached to the recording medium, In the adhesion step, a primary heating step of heating the recording medium is provided. The adhesion step includes a step in which the ejection frequency of the ink composition is 15 kHz or more. The ink composition contains a metal pigment and a solvent component. The solvent component includes an organic solvent. The metal pigment is flaky metal particles whose surface is treated with a compound represented by the following formula (1) or the following formula (2). (R , , [Figure 4] , [Figure 3] , , , , , ,

[0009] -)P(O)(OH)2 ···(1) (R 2 -O-) a P(O)(OH) 3-a ···(2) (In the formula, R 1 , R 2 each independently represents a hydrocarbon group having 14 or more carbon atoms which may be substituted with a substituent, and a represents 1 or 2.)

[0007] One aspect of the recording apparatus according to the present invention is an inkjet head that ejects the ink composition, a primary heating mechanism that performs the primary heating step, and is provided with. Any of the above recording methods is performed.

Brief Description of the Drawings

[0008] [Figure 1] Schematic diagram of an example of drive pulses included in the drive signal of the inkjet head. [Figure 2] Schematic cross-sectional view schematically showing a recording apparatus. [Figure 3] Schematic diagram of a cross-section of a main part of an example of an inkjet head according to an embodiment. [Figure 4] Configuration diagram of an example of a recording apparatus according to an embodiment.

Embodiments for Carrying Out the Invention

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

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

[0011] 1. Recording Method The recording method according to this embodiment comprises an adhesion step of ejecting an ink composition from an inkjet head and adhering it to a recording medium, and a primary heating step of heating the recording medium in the adhesion step.

[0012] 1.1. Adhesion Process In the adhesion process, the ink composition is ejected from the inkjet head and adhered to the recording medium. The adhesion process also includes a step where the ejection frequency of the ink composition is 15 kHz or higher. The ink composition will be described below, followed by a description of the adhesion process.

[0013] 1.1.(i) Ink composition The ink composition contains a metallic pigment and a solvent component.

[0014] 1.1.(i-1) Metallic Pigments Metallic pigments are metal particles whose surfaces have been treated with a surface treatment agent. More specifically, metallic pigments include embodiments in which the surface treatment agent is attached to the surface of the metal particles by chemical bonding or physical adsorption.

[0015] 1.1.(i-2) Metal particles The metal particles are composed of a metallic material in at least a portion of their visible surface, for example, the entire particle or the area near its outer surface is composed of a metallic material. The metal particles have the function of imparting a metallic luster to recordings produced using the ink composition.

[0016] The metal particles only need to be composed of a metallic material in a region including the vicinity of the surface. For example, they may be entirely composed of a metallic material, or they may have a base made of a non-metallic material and a coating made of a metallic material covering the base. Furthermore, the metal particles may have a passive film such as an oxide film formed on their surface. Even with such metal particles, problems such as water resistance and metallic luster have conventionally occurred, but the ink composition of this embodiment can obtain excellent water resistance and metallic luster.

[0017] The metal materials that make up the metal particles can be individual metals or various alloys. Examples include aluminum, silver, gold, platinum, nickel, chromium, tin, zinc, indium, titanium, iron, copper, and alloys containing at least one of these metals. Of these, the metal particles are preferably made of aluminum or aluminum alloys, and more preferably of aluminum. One reason why aluminum and aluminum alloys are preferred is that they have a lower specific gravity compared to metals such as iron. As a result, the sedimentation of the metal pigment dispersed in the ink proceeds very slowly, which suppresses the occurrence of uneven concentration and allows the composition to be stored for a longer period of time. This trend is evident. Furthermore, using metallic pigments made from aluminum or aluminum alloy metal particles allows for improved gloss and a more luxurious feel in recording materials while suppressing increases in production costs for materials manufactured using the ink composition.

[0018] Aluminum and aluminum alloys inherently exhibit superior luster among various metallic materials. However, when attempting to apply particles composed of these materials to a composition, the following problems may arise. Specifically, the storage stability (water resistance) of the composition tends to be low, and when the composition is used as an ink composition, problems such as decreased discharge stability due to increased viscosity caused by gelation are likely to occur. In contrast, even if the metallic pigment uses metal particles made of aluminum or aluminum alloy, these problems can be made less likely to occur by surface treatment with a specific surface treatment agent described later in this embodiment. In other words, the effect of the composition in this embodiment becomes more pronounced when the metal particles are aluminum or aluminum alloy.

[0019] The metal particles are flaky. This makes it easier for the main surface of the metal particles to be arranged to conform to the surface shape of the object to which the composition is applied. As a result, the gloss and other properties of the metal material constituting the metal particles can be more effectively exhibited in the resulting recording, resulting in a superior gloss and high-quality feel of the recording. Furthermore, when the metal particles are flaky, the recording tends to have excellent scratch resistance.

[0020] Furthermore, when metal particles are flaky, their dispersion stability becomes unstable, and when the metal particles aggregate, the surface portions of the metal particles tend to overlap, resulting in coarse particles. For this reason, the effects of the composition of this embodiment are more pronounced in that it exhibits superior dispersion stability and prevents aggregation of metal group particles.

[0021] In this specification, "scale-like" refers to a shape such as a flat plate or a curved plate, where, when observed from a predetermined angle, for example, the area when viewed from above is larger than the area when observed from an angle perpendicular to the direction of observation. In particular, the area S1 [μm²] when observed from the direction in which the projected area is maximized, i.e., when viewed from above. 2 ] and the area S0 [μm²] observed from the direction perpendicular to the observation direction that yields the largest observed area. 2The ratio S1 / S0 to ] is preferably 2 or more, more preferably 5 or more, and even more preferably 8 or more. Furthermore, 10 or more is preferred, and 20 or more is even more preferred. Even more preferably 30 or more. The upper limit of S1 / S0 is not particularly limited, but it is preferably 1000 or less, more preferably 500 or less, and even more preferably 100 or less. Even more preferably 80 or less.

[0022] For this value, for example, observations can be performed on any 50 particles, and the average value calculated for these particles can be adopted. Observations can be performed using, for example, an electron microscope or an atomic force microscope. Alternatively, the volume-average particle diameter (D50) and average thickness described later can be used, and after matching the units, the value can be calculated as volume-average particle diameter (D50) / average thickness, and this can be used as the above range.

[0023] The average thickness of the flaky metal particles is preferably 5 nm or more and 90 nm or less. The lower limit of the average thickness of the metal particles is not particularly limited, but is more preferably 10 nm or more, and even more preferably 15 nm or more. Furthermore, when the metal particles are flaky, the upper limit of the average thickness of the metal particles is not particularly limited, but is more preferably 70 nm or less, even more preferably 50 nm or less, particularly preferably 30 nm or less, even more preferably 20 nm or less, and even more preferably 15 nm or less.

[0024] When the metal particles are flaky and have an average thickness of 5 nm to 90 nm, preferably within the above range, the effects of the flaky particle shape described above become more pronounced.

[0025] The average thickness of metal particles can be measured using an atomic force microscope (AFM). For example, measurements can be taken on any 50 metal particles using atomic force microscopy, and the average value can be used. In other words, the average thickness is the arithmetic mean thickness.

[0026] The preferred range and measurement method for the volume-average particle diameter (D50) of metal particles were determined by measuring the volume-average particle diameter D50 using a laser diffraction / scattering particle size distribution analyzer.

[0027] The metal particles may be manufactured by any method, but if they are made of aluminum, it is preferable that they are obtained by forming an aluminum film using a vapor deposition method and then crushing the film. This method also helps to suppress variations in properties between individual particles. Furthermore, by using this method, even relatively thin metal particles can be suitably manufactured.

[0028] When producing metal particles using such a method, for example, metal particles can be suitably produced by forming a film made of aluminum on a substrate. As the substrate, for example, a plastic film such as polyethylene terephthalate can be used. The substrate may also have a release agent layer on the film-forming surface.

[0029] Furthermore, grinding is preferably carried out by applying ultrasonic vibrations to the film in a liquid. This makes it possible to easily obtain metal particles of the aforementioned particle size, and also suppresses the occurrence of variations in size, shape, and properties among the individual metal particles.

[0030] Furthermore, when grinding is performed using the method described above, suitable liquids include alcohols, hydrocarbon compounds, ether compounds, and polar compounds such as propylene carbonate, γ-butyrolactone, N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, cyclohexanone, and acetonitrile. By using such liquids, it is possible to suppress unintended oxidation of metal particles, achieve particularly excellent productivity of metal particles, and minimize variations in size, shape, and properties between individual particles.

[0031] 1.1. (i-3) Surface treatment agent The metal pigment is metal particles whose surface is treated with a compound represented by formula (1) or formula (2) as a surface treatment agent. The surface treatment agent for treating the surface of the metal particles is a compound represented by the following general formula (1) or the following general formula (2). (R 1 -)P(O)(OH)2 ··· (1) (R 2 -O-) a P(O)(OH) 3-a ··· (2) (In the formula, R 1 , R 2 each independently represents a hydrocarbon group having 14 or more carbon atoms which may be substituted with a substituent, and a represents 1 or 2.)

[0032] The compound represented by the above general formula (1) (substituted or unsubstituted alkyl phosphonic acid) is a compound in which the hydrogen atom of the phosphonic acid is substituted with a (R 1 -) group. Since such a compound has little steric hindrance due to the alkyl moiety, it is likely to be uniformly arranged on the surface of the metal particles, and can improve the dispersion stability and gloss of the metal pigment.

[0033] In addition, the metal particles whose surface is treated with the compound represented by formula (1) or formula (2) have excellent dispersion stability of the metal particles, can suppress the aggregation of the metal particles, and can prevent the metal particles from becoming coarse particles. Therefore, the flow of the ink in the ink head is not suppressed, and even when the ejection frequency is high, the ink can be supplied quickly and the ejection stability is excellent.

[0034] Particularly, when having the primary heating step described later, the inkjet head receives the heat of the primary heating step, the dispersion stability of the metal particles may be broken, the metal particles may aggregate with each other and become coarse particles, but the metal particles whose surface is treated with the compound represented by formula (1) or formula (2) have excellent dispersion stability of the metal particles, can suppress the aggregation of the metal particles, and have excellent ejection stability.

[0035] The compound represented by the above general formula (2) is a compound in which one or two of the three hydroxyl groups of phosphoric acid are esterified with a substituted or unsubstituted alkyl group.

[0036] Metal particles whose surfaces have been treated with a compound represented by formula (1) or formula (2) as a surface treatment agent may be metal particles on which the compound represented by formula (1) or formula (2) has adhered to the surface of the metal particles through a chemical reaction.

[0037] The compound represented by general formula (2) is a diester of a substituted or unsubstituted alkyl group when a is 1, and a monoester of a substituted or unsubstituted alkyl group when a is 2. When a is 1 (diester), the compound represented by general formula (2) has two substituted or unsubstituted alkyl moieties, which sterically hindrances the metal particle surface, making it more difficult for water to approach, and thus tends to make the metal pigment more water-resistant. Hereafter, "monoester" may be referred to as "monoester," and "diester" may be referred to as "diester."

[0038] In the above formula, R 1 and R 2 This refers to a monovalent hydrocarbon group having a carbon skeleton with 14 or more carbon atoms. The hydrocarbon group may contain saturated or unsaturated bonds.

[0039] R 1 , R 2 The substituents may be independently substituted with substituents, and examples of substituents include one or more substituents from among carboxyl groups, hydroxyl groups, amino groups, and oxyalkylene-containing groups. If substituents are present, the R to which the substituent is attached 1 or R 2 The position of the group is more preferable when it is bonded to the carbon atom furthest from P or O, as this tends to result in better dispersion stability of the metal pigment. Of these, the oxyalkylene-containing group is a group having an oxyalkylene structure, and the oxyalkylene structure is also called an alkylene oxide structure. 1 , R 2The number of carbon atoms in the substituent in R 1 , R 2 It is not included in the number of carbon atoms of each. Also, R 1 , R 2 If the compound has substituents, it is more preferable that the number of substituents be one.

[0040] The oxyalkylene-containing group has one or more alkylene oxide units, and may have two or more. In particular, it may have a structure in which multiple alkylene oxide units are repeated. The number of repeating alkylene oxide units is preferably 10 or less, more preferably 4 or less. The lower limit is 1 or more, preferably 2 or more, and more preferably 3 or more. The number of alkylene carbon atoms in the alkylene oxide unit is preferably 1 or more and 4 or less.

[0041] Examples of hydrocarbon groups having a carbon skeleton with 14 or more carbon atoms include saturated hydrocarbon groups that do not have double or tripolymer bonds between carbon atoms, and unsaturated hydrocarbon groups that have double or tripolymer bonds between carbon atoms. The hydrocarbon group may also be an aromatic hydrocarbon group having an aromatic ring structure in its carbon skeleton, or a linear or cyclic aliphatic hydrocarbon group. Linear aliphatic hydrocarbon groups are particularly preferred due to their superior dispersion stability. Aliphatic hydrocarbons having a linear skeleton The base can be either branched or linear, but the linear type is preferred because it offers superior dispersion stability, discharge stability, and gloss.

[0042] The compound represented by the above general formula (1) and the compound represented by the above general formula (2) are R in the formula. 1 , R 2 However, each is preferably a hydrocarbon group having 14 to 32 carbon atoms, more preferably a hydrocarbon group having 15 to 30 carbon atoms, even more preferably a hydrocarbon group having 16 to 22 carbon atoms, and especially preferably a hydrocarbon group having 16 to 20 carbon atoms. By doing so, the dispersion stability and water resistance of the ink composition are improved, and even if sedimentation of the components occurs, the components can be redispersed more easily.1 and R 2 This may be an unsubstituted hydrocarbon group, which is preferable.

[0043] Note that R in the above general formulas (1) and (2) 1 , R 2 Preferably, the carbon atoms have the same number of carbon atoms, and more preferably, they are hydrocarbon groups with the same structure. This increases the tendency for the surface treatment agent to adhere uniformly to the surface of the metal particles, resulting in a better balance of water resistance and glossiness of the recorded material.

[0044] Specific examples of compounds represented by the above general formula (1) include tetradecylphosphonic acid (myristylphosphonic acid), hexadecylphosphonic acid (cetylphosphonic acid), octadecylphosphonic acid (stearylphosphonic acid), and it is preferable that one or more are selected from these. More preferably, one or more are selected from hexadecylphosphonic acid (cetylphosphonic acid) and octadecylphosphonic acid (stearylphosphonic acid), and it is even more preferable that it is octadecylphosphonic acid (stearylphosphonic acid).

[0045] Specific examples of the mono-form of the compound represented by the general formula (2) above include monostearyl phosphate esters.

[0046] A specific example of the di-isomer of the compound represented by the above general formula (2) is distearyl phosphate.

[0047] Among the compounds represented by formula (2), the compound in which a is 2, i.e., the phosphate diester (di-form), has two alkyl groups, and since more alkyl groups can be introduced onto the metal particle surface, the hydrophobicity of the pigment surface is increased, and the water resistance of the pigment can be improved.

[0048] The surface treatment agent more preferably contains either the compound represented by formula (1) or the compound represented by formula (2) in which a is represented by 2. In this way, the surface treatment agent tends to adhere more uniformly to the surface of the metal particles, and a better balance of water resistance and gloss can be achieved.

[0049] Furthermore, the surface treatment agent is preferably present in an amount of 0.5% to 60% by mass, more preferably 1% to 50% by mass, more preferably 5% to 40% by mass, and even more preferably 5% to 30% by mass, based on 100% by mass of the total mass of the metal particles. Moreover, 10% to 20% by mass is preferable. With such a ratio, water resistance is further improved, and even if sedimentation of the components occurs, the components can be redispersed more easily.

[0050] The mass of the surface treatment agent is the mass of the surface treatment agent contained in the ink composition. If the surface treatment agent contained in the ink composition is a surface treatment agent attached to metal particles, then the mass of the surface treatment agent is also the mass of the surface treatment agent attached to the metal particles.

[0051] Furthermore, the ink composition according to this embodiment may be used without impairing the effects of the present invention. The product may also contain surface treatment agents other than priming agents. Examples of such surface treatment agents include fluorine-based compounds. Preferably, fluorine-based compounds include compounds containing fluorine and one or more elements selected from phosphorus, sulfur, and nitrogen as constituent elements. Specifically, examples include fluorine-based phosphonic acids, fluorine-based carboxylic acids, fluorine-based sulfonic acids, and salts thereof.

[0052] Surface treatment of metal particles with a surface treatment agent may be carried out, for example, by including the surface treatment agent in the liquid when forming metal particles by crushing a metal film formed by a vapor phase deposition method in a liquid.

[0053] 1.1.(i-4) Volume-average particle diameter The volume-average particle diameter D50 of a metal pigment obtained by treating metal particles with a surface treatment agent is preferably 1 μm or less, more preferably 0.5 μm or less, even more preferably 200 nm to 500 nm, and particularly preferably 300 nm to 500 nm.

[0054] If the particle size of the metal pigment is within the above range, nozzle clogging during inkjet ejection can be further reduced. Furthermore, if the particle size of the metal pigment is within the above range, good water resistance and sufficient dispersibility can be more easily obtained even if the specific surface area of ​​the metal pigment is large.

[0055] The volume-average particle size D50 of metallic pigments can be measured in the same manner as described in the section on metallic particles.

[0056] The content of metal pigment in the ink composition is preferably 0.3% to 30% by mass, more preferably 0.5% to 20% by mass, even more preferably 0.8% to 15% by mass, and even more preferably 1.0% to 10% by mass, based on the total amount of the ink composition. Furthermore, 1.0% to 5% by mass is preferred, and 1.0% to 3% by mass is even more preferred.

[0057] 1.1.(ii) Solvent component The ink composition contains a solvent component. Examples of solvent components include organic solvents and water. The solvent component content in the ink composition is preferably 40% by mass or more, more preferably 50 to 99.5% by mass, even more preferably 60 to 99% by mass, and particularly preferably 70 to 98% by mass. 1.1.(ii-1A) Organic Solvents Examples of organic solvents include esters, alkylene glycol ethers, cyclic esters, nitrogen-containing solvents, alcohols, and polyhydric alcohols. Examples of nitrogen-containing solvents include cyclic amides and acyclic amides. Examples of acyclic amides include alkoxyalkylamides.

[0058] Esters include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, and diethylene glycol monobutyl ether acetate. Glycol monoacetates such as propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, methoxybutyl acetate, etc., ethylene glycol diacetate, diethylene glycol diacetate, propylene glycol diacetate, dipropylene glycol diacetate, ethylene glycol acetate propionate, ethylene glycol acetate butyrate, diethylene glycol acetate butyrate, diethylene glycol acetate propionate, diethylene glycol acetate butyrate, propylene glycol acetate propionate, propylene glycol acetate butyrate, dipropylene glycol acetate butyrate Examples include glycol diesters such as dipropylene glycol acetate propionate.

[0059] The alkylene glycol ethers can be any monoether or diether of alkylene glycol, with alkyl ethers being preferred. Specific examples include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, and tripropylene glycol monobutyl ether. Examples include alkylene glycol monoalkyl ethers such as ethyl ether, and alkylene glycol dialkyl ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl butyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, triethylene glycol methyl butyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, and tripropylene glycol dimethyl ether.

[0060] Furthermore, of the alkylene glycols mentioned above, diethers tend to dissolve or swell the resin in the ink composition more easily than monoethers, and are therefore preferred in that they can further improve friction fastness.

[0061] Examples of cyclic esters include cyclic esters (lactones) such as β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, β-butyrolactone, β-valerolactone, γ-valerolactone, β-hexanolactone, γ-hexanolactone, δ-hexanolactone, β-heptanolactone, γ-heptanolactone, δ-heptanolactone, ε-heptanolactone, γ-octanolactone, δ-octanolactone, ε-octanolactone, δ-nonalactone, ε-nonalactone, and ε-decanolactone, as well as compounds in which the hydrogen atoms of the methylene group adjacent to the carbonyl group are substituted with alkyl groups having 1 to 4 carbon atoms.

[0062] Examples of alkoxyalkylamides include 3-methoxy-N,N-dimethylpropionamide, 3-methoxy-N,N-diethylpropionamide, 3-methoxy-N,N-methylethylpropionamide, 3-ethoxy-N,N-dimethylpropionamide, 3-ethoxy-N,N-diethylpropionamide, 3-ethoxy-N,N-methylethylpropionamide, 3-n-butoxy-N,N-dimethylpropionamide, 3-n-butoxy-N,N-diethylpropionamide, 3-n-butoxy-N,N-methylethylpropionamide, 3-n-propoxy-N,N-dimethylpropionamide, 3-n-propoxy-N,N-diethylpropionamide, and 3-n-propoxy-N,N-methylethylpropionamide. Examples include ethylpropionamide, 3-iso-propoxy-N,N-dimethylpropionamide, 3-iso-propoxy-N,N-diethylpropionamide, 3-iso-propoxy-N,N-methylethylpropionamide, 3-tert-butoxy-N,N-dimethylpropionamide, 3-tert-butoxy-N,N-diethylpropionamide, 3-tert-butoxy-N,N-methylethylpropionamide, etc.

[0063] Examples of cyclic amides include lactams, such as pyrrolidones including 2-pyrrolidone, 1-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, 1-propyl-2-pyrrolidone, and 1-butyl-2-pyrrolidone. These are preferred in that they promote resin film formation, with 2-pyrrolidone being particularly preferred.

[0064] Examples of alcohols include compounds in which one hydrogen atom of an alkane is replaced by a hydroxyl group. The alkane preferably has 10 or fewer carbon atoms, more preferably 6 or fewer, and even more preferably 3 or fewer. The alkane has 1 or more carbon atoms, preferably 2 or more. The alkane may be linear or branched. Examples of alcohols include methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butanol, 2-butanol, tert-butanol, iso-butanol, n-pentanol, 2-pentanol, 3-pentanol, and tert-pentanol, phenoxyethanol, benzyl alcohol, and phenoxypropanol.

[0065] When an ink composition contains alcohols, it is more preferable to select from aromatic monohydric alcohols and aliphatic monohydric alcohols having four or more carbon atoms. This may improve the dispersion stability of the metal pigment. Aromatic monohydric alcohols and aliphatic monohydric alcohols having four or more carbon atoms are somewhat hydrophobic, have good affinity with surface treatment agents for metal pigments, and can improve the water dispersibility of particles. In other words, these alcohols can play a role in bridging the hydrophobicity and hydrophilicity between the hydrophobicity of the surface of the metal pigment and the water molecules as a solvent.

[0066] Aliphatic monohydric alcohols having 4 or more carbon atoms are preferably those with 4 to 10 carbon atoms, and more preferably those with 4 to 8 carbon atoms. Aromatic monohydric alcohols are monohydric alcohols having an aromatic ring, such as a benzene ring or a naphthalene ring. In aromatic monohydric alcohols, the number of carbon atoms in the alkylene skeleton to which the hydroxyl group is bonded is preferably 1 to 4, and more preferably 1 to 3.

[0067] The content (total content) of aromatic monohydric alcohols and / or aliphatic monohydric alcohols having 4 or more carbon atoms is preferably 0.5% by mass or more, more preferably 1% by mass or more, and particularly preferably 3% by mass or more, based on the total mass of the ink composition. Furthermore, the content of aromatic monohydric alcohols and / or aliphatic monohydric alcohols having 4 or more carbon atoms is preferably 40% by mass or less, preferably 30% by mass or less, more preferably 20% by mass or less, and particularly preferably 10% by mass or less. It is also preferable that the content of aromatic monohydric alcohols and / or aliphatic monohydric alcohols having 4 or more carbon atoms be within the above range relative to the total mass of the liquid medium components contained in the ink composition.

[0068] Polyhydric alcohols are molecules that contain two or more hydroxyl groups. Polyhydric alcohols can be further classified into, for example, alkanediols and polyols.

[0069] Alkanediols include, for example, compounds in which an alkane is substituted with two hydroxyl groups. Examples of alkanediols include ethylene glycol (also known as ethane-1). ,2-diol), propylene glycol (also known as propane-1,2-diol), 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-octanediol, 1,3-propanediol, 1,3-butylene glycol (also known as 1,3-butanediol), 1,4-butanediol, 2,3-butanediol, 1,2-pentanediol, 1,5-pentanediol, 2,4-pentanediol, 2-methyl- Examples include 1,3-propanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,3-pentanediol, 3-methyl-1,5-pentanediol, 2-methylpentane-2,4-diol, 1,6-hexanediol, 2-ethyl-2-methyl-1,3-propanediol, and 2-methyl-2-propyl-1,3-propanediol.

[0070] Examples of polyols include condensates formed by the intermolecular condensation of two or more alkanediol molecules via hydroxyl groups, and compounds having three or more hydroxyl groups.

[0071] Examples of condensates formed by the intermolecular condensation of two or more alkanediol molecules at their hydroxyl groups include dialkylene glycols such as diethylene glycol and dipropylene glycol, and trialkylene glycols such as triethylene glycol and tripropylene glycol.

[0072] Compounds having three or more hydroxyl groups are compounds with an alkane or polyether structure as their backbone and containing three or more hydroxyl groups. Examples of compounds having three or more hydroxyl groups include glycerin, trimethylolethane, trimethylolpropane, 1,2,5-hexanetriol, 1,2,6-hexanetriol, pentaerythritol, and polyoxypropylenetriol.

[0073] The above organic solvents may be used individually or in combination of two or more.

[0074] Among the above organic solvents, it is preferable to include one or more selected from alkylene glycol ethers and cyclic esters, and it is even more preferable to include one or more selected from diethylene glycol diethyl ether, tetraethylene glycol monobutyl ether, and γ-butyrolactone.

[0075] The content of the organic solvent is preferably 0.5% by mass or more, relative to the total mass of the ink composition. More preferably 5% by mass or more, even more preferably 10% by mass or more, and particularly preferably 15% by mass or more. Even more preferably 20% by mass or more, and even more preferably 30% by mass or more. The upper limit of the organic solvent content is preferably 99.5% by mass or less, preferably 70% by mass or less, and more preferably 60% by mass or less. It is also preferable that the content of the organic solvent be within the above range relative to the total mass of the liquid media components contained in the ink composition.

[0076] The ink composition may also be a solvent-based ink, which is preferable. A solvent-based ink is one in which the solvent component (solvent) contained in the ink is mainly an organic solvent. The water content in the solvent-based ink is preferably 2% by mass or less, more preferably 1% by mass or less, even more preferably 0.5% by mass or less, and still more preferably 0.1% by mass or less. The lower limit is 0% by mass or more.

[0077] When the ink composition is a solvent-based ink, the content of the organic solvent is preferably 50% by mass or more relative to the ink. More preferably 60 to 99.5% by mass, more preferably 70 to 99% by mass, and even more preferably 80 to 98% by mass.

[0078] 1.1.(ii-1B) Water The ink composition may be a water-based ink. A water-based ink is one in which the solvent component (solvent) contained in the ink is mainly water. The water content in a water-based ink is preferably 40% by mass or more. Furthermore, the water content is preferably 50% by mass or more and 99.5% by mass or less, more preferably 60% by mass or more and 99% by mass or less, and even more preferably 70% by mass or more and 90% by mass or less.

[0079] Water-based inks also contain organic solvents as solvent components. The content of organic solvents is preferably 40% by mass or less, more preferably 35% by mass or less, relative to the ink. Furthermore, 0.5% by mass or more and 30% by mass or less is preferred, 1% by mass or more and 20% by mass or less is more preferred, and 3% by mass or more and 10% by mass or less is even more preferred.

[0080] 1.1.(ii-2) Other components The ink composition may contain other components. These other components may include dispersants, resins, and other substances.

[0081] (Dispersant) The ink composition may contain a dispersant. Examples of dispersants include resin dispersants and polyoxyalkyleneamine compounds, and are selected from those that can provide good dispersion stability of the metal pigment in the ink composition.

[0082] Examples of resin dispersants include (meth)acrylic resins and their salts such as poly(meth)acrylic acid, (meth)acrylic acid-acrylonitrile copolymer, (meth)acrylic acid-(meth)acrylic acid ester copolymer, vinyl acetate-(meth)acrylic acid ester copolymer, vinyl acetate-(meth)acrylic acid copolymer, vinylnaphthalene-(meth)acrylic acid copolymer; styrene-(meth)acrylic acid copolymer, styrene-(meth)acrylic acid-(meth)acrylic acid ester copolymer, styrene-α-methylstyrene-(meth)acrylic acid copolymer, and styrene-α-methylstyrene-(meth)acrylic acid copolymer. Examples of water-soluble resins include styrene-based resins and their salts, such as lylic acid-(meth)acrylic acid ester copolymers, styrene-maleic acid copolymers, and styrene-maleic anhydride copolymers; urethane-based resins and their salts, which are polymer compounds (resins) containing urethane bonds formed by the reaction of isocyanate groups and hydroxyl groups, and which may be linear and / or branched, with or without crosslinking structures; polyvinyl alcohols; vinylnaphthalene-maleic acid copolymers and their salts; vinyl acetate-maleic acid ester copolymers and their salts; and vinyl acetate-crotonic acid copolymers and their salts.

[0083] If the ink composition contains a dispersant, the lower limit of the dispersant content is not particularly limited, but is preferably 0.01% by mass or more, more preferably 0.06% by mass or more, and even more preferably 0.10% by mass or more. The upper limit of the dispersant content is not particularly limited, but is preferably 4.0% by mass or less, more preferably 2.0% by mass or less, and even more preferably 1.0% by mass or less.

[0084] (resin) The ink composition according to this embodiment may contain a resin. The resin can function as a binder. Examples of resins include acrylic resins, rosin-modified resins, terpene resins, polyester resins, polyamide resins, epoxy resins, vinyl chloride resins, vinyl chloride-vinyl acetate copolymers, cellulose resins (e.g., cellulose acetate butyrate, hydroxypropyl cellulose), polyvinyl butyral, polyacrylic polyols, polyvinyl alcohol, urethane resins, etc. Among these, acrylic resins and poly... It is preferable to include one or more resins selected from polyester resins, urethane resins, and cellulose-based resins, and more preferably to include an acrylic resin. The acrylic resin is a resin obtained by polymerizing at least acrylic monomers, and may also be a copolymer resin of acrylic monomers and other monomers. Examples of other monomers include vinyl monomers.

[0085] The lower limit of the resin content is preferably 0.01% by mass or more, more preferably 0.06% by mass or more, even more preferably 0.10% by mass or more, and particularly preferably 0.15% by mass or more, based on the total mass of the ink composition. The upper limit of the resin content is preferably 3.0% by mass or less, more preferably 1.0% by mass or less, even more preferably 0.5% by mass or less, and particularly preferably 0.3% by mass or less, based on the total mass of the ink composition.

[0086] (Other ingredients) The ink composition according to this embodiment may further contain the following components. Examples of such components include water, leveling agents, polymerization accelerators, polymerization inhibitors, photopolymerization initiators, dispersants, surfactants, penetration accelerators, humectants, colorants, fixatives, fungicides, preservatives, antioxidants, chelating agents, thickeners, sensitizers, and the like.

[0087] It is preferable to use pure or ultrapure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, or distilled water. In particular, water that has been sterilized by ultraviolet irradiation or hydrogen peroxide addition is preferable because it can suppress the growth of mold and bacteria for a long period of time.

[0088] Preferred surfactants include silicone-based surfactants and acetylene glycol-based surfactants.

[0089] Furthermore, the ink composition of this embodiment is preferably a solvent-based ink or a water-based ink. In this case, it is necessary to obtain excellent image quality by drying the ink adhering to the recording medium quickly through the primary heating process, and the present invention is particularly useful in obtaining excellent ejection stability when performing the primary heating process. It is particularly preferable that it be a solvent-based ink. Also, it is preferable that the ink composition is not an ultraviolet-curable ink.

[0090] 1.1.(iii) Discharge frequency The adhesion step of the recording method in this embodiment includes a step in which the ejection frequency of the ink composition is 15 kHz or higher. The adhesion step may also include a step in which the ejection frequency is less than 15 kHz. The drive signal used for the inkjet head will be explained using a printer using a piezoelectric element as an example.

[0091] Figure 1 illustrates a drive pulse included in a drive signal. In Figure 1, the vertical axis represents the potential of the drive pulse, and the horizontal axis represents time. The potential difference (drive voltage) from the lowest potential VL to the highest potential VH of the drive pulse is set to vh1. The drive pulse includes an expansion element p1 that changes the potential to the positive side from the reference potential VB to the expansion potential VH to expand the pressure chamber, an expansion maintenance element p2 that maintains the expansion potential VH for a certain period of time, a contraction element p3 that changes the potential to the negative side from the expansion potential VH to the contraction potential VL to rapidly contract the pressure chamber, a contraction maintenance (vibration damping hold) element p4 that maintains the contraction potential VL for a certain period of time, and a recovery element p5 that returns the potential from the contraction potential VL to the reference potential VB.

[0092] When a drive pulse is supplied to the discharge element, it operates as follows: First, when the expansion element p1 is supplied to the piezoelectric element, the piezoelectric element contracts, and consequently the pressure chamber changes (expands) from a reference volume corresponding to the reference potential VB to a maximum volume corresponding to the highest potential VH. This causes the meniscus of the ink composition exposed at the nozzle to be drawn into the pressure chamber. The expanded state of this pressure chamber is maintained constant throughout the supply period of the expansion maintenance element p2.

[0093] When a contraction element p3, which changes the voltage in the opposite direction to the voltage change caused by the expansion element p1, is supplied to the piezoelectric element following the expansion maintenance element p2, the piezoelectric element expands, causing the pressure chamber to rapidly change (contract) from the maximum volume to the minimum volume corresponding to the lowest potential VL. This rapid contraction of the pressure chamber pressurizes the ink composition inside the pressure chamber, causing several pl to tens of pl of ink composition to be discharged from the nozzle. This contracted state of the pressure chamber is maintained for a short time during the supply period of the contraction maintenance element p4, after which a vibration damping element p5 is supplied to the piezoelectric element, and the pressure chamber returns from the volume corresponding to the lowest potential VL to the reference volume corresponding to the reference potential VB. It is also possible to increase the amount of liquid discharged from the nozzle by increasing the slope (absolute value of the voltage change per unit time) between the expansion element p1 and the contraction element p3. After p5, a predetermined time interval is observed, and then the next series of drive signals p1 to p5 are supplied to the element again. In this way, ink droplets are driven continuously at regular time intervals and ink is discharged.

[0094] By selectively outputting such drive pulses from the drive signal to the piezoelectric element of the inkjet head, liquid is ejected from the corresponding nozzle onto the target material (recording medium). Furthermore, the liquid ejection operation of the inkjet head can be controlled by controlling this drive signal.

[0095] While the drive signals may differ in detail depending on the inkjet head design, common control elements include the ejection frequency when ejecting droplets and the drive voltage for ejection (amplitude (potential difference) in the waveform during ejection).

[0096] The discharge frequency is related to the time interval when the head is driven continuously, and is related to the time interval at which a series of drive signals p1 to p5 are continuously supplied to the element. In Figure 1, if the time interval (period) between one series of drive signals p1 to p5 and the next series of drive signals p1 to p5 is A, then the discharge frequency is the reciprocal of A. Therefore, a higher discharge frequency results in a shorter time interval A. The unit of discharge frequency is kHz.

[0097] The discharge frequency is related to the time between dispensing one droplet and dispensing the next, and is the reciprocal of the time between dispensing one droplet and dispensing the next. Therefore, for example, a higher discharge frequency means a shorter time between dispensing one droplet and dispensing the next.

[0098] Regarding the potential difference portion of the waveform, if there is no expansion element p1 to maintain the expansion state of the pressure chamber, the potential difference (driving voltage) corresponds to the contraction potential VL from the reference potential VB. Furthermore, by controlling the driving voltage and voltage waveform, the flight speed of the ejected droplets can also be controlled. This is the same for both piezo jets and thermal jets, and the driving method of the inkjet head in this embodiment is not limited.

[0099] The recording method of this embodiment includes a step in which the ejection frequency is 15 kHz or higher. For example, when recording a high-resolution image, the potential difference between the highest potential VH and the lowest potential VL may be reduced to set the ink droplet size smaller. In this case, the image density can be increased by reducing the scanning speed of the inkjet head to compensate for the amount of ink per unit area of ​​the image, but it is also possible to avoid reducing the scanning speed of the inkjet head by increasing the ejection frequency. Therefore, the overall recording speed of the image can be improved by increasing the ejection frequency.

[0100] However, in this case, increasing the ejection frequency can lead to insufficient ink fluidity within the inkjet head, partly because it increases the mass of ink ejected from the inkjet head per unit time. In the recording method of this embodiment, since an ink composition with good dispersion stability of the metal pigment described above is used, the decrease in ink fluidity is suppressed even at high ejection frequencies, and stable ejection can be achieved. This effect is particularly pronounced when using a recording device having an elongated ink channel, as described later.

[0101] In the example shown in Figure 1, the ink weight ejected by a series of drive signals from p1 to p5 is preferably 0.5 ng or more, more preferably 1 ng or more. On the other hand, 20 ng or less is preferable. Furthermore, 3 to 15 ng is preferable, 5 to 13 ng is even preferable, and 8 to 12 ng is even preferable. In this case, glossiness and ejection stability are better and therefore preferable.

[0102] 1.2.Primary heating process The recording method according to this embodiment includes a primary heating step, which is a step of heating the ink composition adhering to the recording medium at an early stage. The primary heating step is a step of heating and drying the ink adhering to the recording medium at an early stage. The primary heating step is a heating step to dry at least a portion of the liquid medium of the ink adhering to the recording medium to the extent that the flow of the ink is reduced. The primary heating step may be performed so that the ink adheres to the heated recording medium, or it may be performed to heat the recording medium at an early stage after adhesion. It is preferable that heating of ink droplets that have landed on the recording medium begins no later than 0.5 seconds after the ink droplets land.

[0103] The primary heating process is preferably carried out by an IR heater, microwave radiation, a platen heater, or by blowing warm air onto the recording medium using a fan.

[0104] The heating in the primary heating step can be performed before the adhesion step, simultaneously with the adhesion step, or shortly after the adhesion step, and it is preferable that it be performed simultaneously. The ink adhesion step can be carried out with this heating sequence. In particular, it is preferable that the recording medium is heated and then the ink composition is adhered to the heated recording medium by the ink adhesion step.

[0105] Having a primary heating step is preferable because it allows the ink composition to dry quickly on the recording medium, thereby suppressing ink bleeding. For example, without a primary heating step, ink droplets adhering to the recording medium remain wet for a while, causing them to clump together and resulting in bleeding and degraded image quality. This results in poor gloss. In contrast, with a primary heating step, the ink droplets are dried quickly, suppressing clumping, resulting in excellent image quality and superior gloss.

[0106] However, when performing the primary heating step, if the heating temperature is too high, the ink may lose its fluidity before the metal pigment can leaf out on the recording medium, which can lead to insufficient leafing and a decrease in gloss. The metal pigment treated with the treatment agent of this embodiment can suppress the decrease in gloss caused by insufficient leafing when performing the primary heating step.

[0107] In the primary heating step where the ink composition is heated, the surface temperature of the recording surface of the recording medium is preferably 30°C or higher. On the other hand, 60°C or lower is preferable. Furthermore, 35°C to 55°C is preferable, and even more preferably 30°C to 50°C. When the surface temperature of the recording medium is as described above, it is preferable to have better prevention of bleeding and ejection stability.

[0108] The recording medium surface temperature in the primary heating process is either the surface temperature of the recording medium when the ink is applied, or, if heating is performed after application, the temperature of the recording medium at the time of heating. It is also the highest temperature during recording.

[0109] 1.3. Post-heating process The recording method according to this embodiment may include a post-heating step (secondary heating step) for heating the recording medium after the ink adhesion step. The post-heating step is a heating step that heats the recording medium sufficiently to complete the recording and allow the recorded material to be used. The post-heating step is a heating step for thoroughly drying the solvent components of the ink. It is preferable that the post-heating step be started more than 0.5 seconds after the ink has adhered to the recording medium. For example, it is preferable to start heating a recording area of ​​the recording medium more than 0.5 seconds after the adhesion of ink to that area is completely finished.

[0110] The heating of the recording medium in the post-heating step can be carried out, for example, using an appropriate heating means. In this case, the surface temperature of the recording medium is preferably 40°C or higher, more preferably 45°C or higher, and even more preferably 50°C or higher. There is no upper limit, but 120°C or lower is preferred. Furthermore, 75°C or lower, 70°C or lower, and 60°C or lower are even more preferred. In addition, the heating temperature is preferably below the softening point of the recording medium's substrate.

[0111] 2. Recording device An example of a recording device that performs the recording method of this embodiment is one that includes an inkjet head for ejecting an ink composition and a primary heating mechanism for performing a primary heating step, and performs recording by the recording method described above.

[0112] 2.1. Outline of the device configuration Figure 2 is a schematic cross-sectional view illustrating a recording device. As shown in Figure 2, the recording device 1 comprises an inkjet head 2, an IR heater 3, a platen 4, a heating element 5, a cooling fan 6, a preheater 7, and a ventilation fan 8. The inkjet head is mounted on a carriage (not shown) and performs a main scan in the front-back direction in the figure to deposit ink onto the recording medium M. The platen 4 is also provided with a platen heater (not shown). The recording device 1 includes a control unit (not shown) that controls each part to perform recording. The inkjet head 2 receives ink from an ink reservoir (not shown).

[0113] 2.2. Configuration related to the inkjet head The inkjet head 2, which is an inkjet head, is configured to record onto the recording medium M by ejecting and depositing an ink composition from the nozzles of the inkjet head 2. As shown in Figure 2, the inkjet head 2 is a serial inkjet head that deposits ink onto the recording medium M by scanning it multiple times in the main scanning direction relative to the recording medium M. The inkjet head 2 is mounted on a carriage (not shown). The inkjet head 2 is scanned multiple times in the main scanning direction relative to the recording medium M by the operation of a carriage movement mechanism that moves the carriage in the media width direction of the recording medium M (back-to-front direction in the figure). The media width direction is the main scanning direction of the inkjet head 2. Scanning in the main scanning direction is also called the main scan.

[0114] Here, the main scanning direction is the direction in which the carriage equipped with the inkjet head 2 moves. In Figure 2, this direction intersects with the sub-scanning direction, which is the transport direction of the recording medium M indicated by arrow SS. Recording is then performed on the recording medium M by repeatedly performing the main scanning of the inkjet head 2 and the sub-scanning, which is the transport of the recording medium M.

[0115] Conventional methods can be used for ejecting ink droplets from the inkjet head 2. For example, a method that uses the vibration of a piezoelectric element to eject droplets, that is, an ejection method that forms ink droplets by the mechanical deformation of an electrostrictive element, can be used.

[0116] 2.3.Primary heating mechanism The recording device 1 may be equipped with a primary heating mechanism that performs a primary heating process to heat the recording medium M when ejecting ink from the inkjet head 2 and adhering it to the recording medium. The primary heating mechanism can be of the conduction type, blower type, radiant type, etc. The conduction type conducts heat to the recording medium from a component in contact with the recording medium. For example, a platen heater can be used. Although not shown, the platen heater is provided integrally with the platen 4. The blower type sends ambient temperature air or warm air to the recording medium to dry the ink. For example, a blower fan can be used. The radiant type heats the recording medium by radiating heat-generating radiation to it. For example, IR radiation can be used. Although not shown, a heater similar to the platen heater may be provided immediately downstream of the platen 4 in the SS direction. These primary heating mechanisms may be used individually or in combination.

[0117] For example, the primary heating mechanism includes an IR heater 3 and a platen heater.

[0118] Furthermore, by using the IR heater 3, the recording medium M can be heated radiantly by infrared radiation from the inkjet head 2 side. This makes it easier for the inkjet head 2 to be heated at the same time, but the temperature can be raised without being affected by the thickness of the recording medium M, compared to when the recording medium M is heated from the back side by a platen heater or the like.The primary heating mechanism may also include various fans (e.g., ventilation fan 8) that blow hot air or air at the same temperature as the environment onto the recording medium M to dry the ink on the recording medium M.

[0119] The platen heater can heat the recording medium M via the platen 4 at a position opposite the inkjet head 2. The platen heater is capable of heating the recording medium M by conduction and is used as needed in the inkjet recording method.

[0120] Furthermore, the recording device 1 may be equipped with a preheater 7 that preheats the recording medium M before ink is applied to it.

[0121] 2.4. Post-heating mechanism The system may also include a post-heating mechanism that performs a post-heating step after the white ink application step and the non-white ink application step to heat the recording medium, dry the ink, and fix it in place.

[0122] The heating element 5 used in the post-heating mechanism dries and solidifies the ink adhering to the recording medium M. When the heating element 5 heats the recording medium M on which the image is recorded, moisture and other substances contained in the ink evaporate more quickly, and an ink film is formed by the resin contained in the ink. In this way, the ink film firmly fixes or adheres to the recording medium M, resulting in excellent film-forming properties, and a high-quality image can be obtained in a short time.

[0123] 2.5. Other Configurations 2.5.1. Cooling mechanism etc. The recording device 1 may have a cooling fan 6. After the ink recorded on the recording medium M dries, the ink on the recording medium M is cooled by the cooling fan 6, thereby forming an ink coating film with good adhesion on the recording medium M.

[0124] 2.5.2.Method The recording device shown in Figure 2 is a serial printer that performs recording using a so-called serial method. The recording device may also be a line printer equipped with a line head that performs recording using a line method.

[0125] The line head has a nozzle row in which multiple nozzles are arranged in the width direction of the recording medium, and has a length greater than or equal to the width of the recording medium M being transported, and it transports the recording medium M in one go. This allows for recording images in the width direction of the recording medium. Recording can be performed in a single scan. Alternatively, after performing one scan by transporting the recording medium, it is possible to perform recording with two or more scans by returning the recording medium in the reverse direction of transport and transporting it again to perform another scan.

[0126] The scanning may be performed by a head whose position is fixed relative to the transported recording medium, or by a head that moves while scanning is performed relative to the recording medium fixed in the platen area.

[0127] Furthermore, a recording device capable of line-type recording can be configured similarly to the one shown in Figure 2, except that the inkjet head 2 is replaced with a line head. Specifically, the heating mechanisms such as the ventilation fan 8, IR heater 3, platen heater, and preheater 7, which are located above the inkjet head 2 in Figure 2, can be similarly placed above or below the line head. Alternatively, a post-heating mechanism such as the heating heater 5 and cooling fan 6 shown in Figure 1 may also be included.

[0128] 2.5.3. Details of the inkjet head In some cases, the distance from the pressure chamber to the nozzle of the inkjet head of a recording device may be 0.5 mm or more. Figure 3 is a schematic cross-sectional view of the main part of an inkjet head 100, which is an example of an inkjet head in a recording device. In Figure 3, the flow of ink from the ink supply chamber 40 to the nozzle hole 12 during ink ejection is schematically shown by dashed arrows.

[0129] Note that in Figure 3, the piezoelectric element 32 is shown in a simplified form. Also, the inkjet head 100 is configured to include a communication plate 110 and a cover 150.

[0130] As shown in Figure 3, the inkjet head 100 comprises a nozzle plate 10 having a plurality of nozzle holes 12, a plurality of pressure chambers 20 communicating with each of the plurality of nozzle holes 12 formed in the nozzle plate 10, a diaphragm 30 that changes the volume of each of the plurality of pressure chambers 20, and an ink supply chamber 40 that supplies ink to the plurality of pressure chambers 20. Note that the plurality of components are arranged in the depth direction of the drawing, and Figure 3 shows a cross-section of one set of these components.

[0131] The nozzle plate 10 has a plurality of nozzle holes 12 for ejecting ink, and these nozzle holes 12 are arranged in a row, and a nozzle surface 13 is formed on the surface of the nozzle plate 10. The number of nozzle holes 12 provided in the nozzle plate 10 is not particularly limited.

[0132] The inkjet head 100 includes a pressure chamber substrate 120 for forming a pressure chamber 20. As shown in Figure 3, the pressure chamber substrate 120 includes a communication plate 110 between it and the nozzle plate 10 as a flow path forming substrate. The communication plate 110 partitions the space between the nozzle plate 10 and the pressure chamber substrate 120, thereby forming an ink supply chamber 40 (liquid storage section), a supply port 126 communicating with the ink supply chamber 40, and a pressure chamber 20 communicating with the supply port 126. That is, the ink supply chamber 40, the supply port 126, and the pressure chamber 20 are partitioned by the nozzle plate 10, the communication plate 110, the pressure chamber substrate 120, and the diaphragm 30.

[0133] The communication plate 110 has a communication hole 127 that communicates from the pressure chamber 20 to the nozzle hole 12. An ink discharge port 128 is formed at the end of the communication hole 127, which is formed on the surface of the communication plate 110 that contacts the nozzle plate 10. The discharge port 128 communicates with the nozzle hole 12 formed in the nozzle plate 10.

[0134] The diaphragm 30 is provided in contact with the pressure chamber substrate 120, and a piezoelectric element 32 is formed in contact with the diaphragm 30. The piezoelectric element 32 is electrically connected to a piezoelectric element drive circuit (not shown) and can operate (vibrate, deform) based on signals from the piezoelectric element drive circuit. The diaphragm 30 deforms due to the operation of the piezoelectric element 32, and by changing the volume of the pressure chamber 20, the internal pressure of the pressure chamber 20 can be changed. The piezoelectric element 32 is not particularly limited, but for example, an element that deforms when a voltage is applied (an electromechanical conversion element) can be mentioned.

[0135] Furthermore, the inkjet head 100 includes a compliance sheet 140 and a cover 150 that houses a piezoelectric element 32 as components that form part of the ink flow path. The compliance sheet 140 forms a supply port 126 that communicates with the ink supply chamber 40 between itself and the communication plate 110. The compliance sheet 140 is also a flexible elastic film and has the function of acting as a damper for ink ejection and flow, and of deforming when the volume of ink expands, thereby suppressing damage to the inkjet head 100.

[0136] In this embodiment, the ink supply chamber 40, the supply port 126, the pressure chamber 20, and the communication hole 127 are described separately, but all of these are liquid flow paths, and as long as the pressure chamber 20 is formed, the flow path can be designed in any way.

[0137] The pressure chamber 20 formed by the above configuration is a space partitioned by the communication plate 110, the pressure chamber substrate 120, and the diaphragm 30, and does not include the supply port 126, the communication hole 127, the discharge port 128, and the nozzle hole 12. In other words, the pressure chamber 20 is defined as the space opposite to the parts that apply pressure to the ink, such as the diaphragm 30, the pressure chamber substrate 120, and the communication plate 110, and the space adjacent to this space whose cross-sectional area in the direction in which the ink moves is equal to that of this space, and the volume of the pressure chamber 20 is this volume. Thus, the pressure chamber 20 is defined as a space whose volume changes with the displacement of the diaphragm 30, and does not include any narrowed flow paths or the like that communicate with this space.

[0138] The volume of the pressure chamber is preferably 1000 pl to 4000 pl, more preferably 1500 pl to 3700 pl, and even more preferably 2000 pl to 3300 pl. The volume of the pressure chamber is the volume per pressure chamber.

[0139] The distance from the pressure chamber to the nozzle of the inkjet head is the distance from the end of the pressure chamber where the ink flows towards the nozzle hole to the tip of the nozzle hole. In the example in Figure 3, the distance from the pressure chamber to the nozzle of the inkjet head refers to the distance from the pressure chamber 20 to the nozzle hole 12, and in the example in Figure 3, it is equal to the sum of the thickness direction length d1 of the communication plate 110 and the thickness direction length of the nozzle plate 10.

[0140] The distance from the pressure chamber of the inkjet head to the nozzle is not limited, but is preferably 0.2 mm or more. It is also preferably 5 mm or less. Furthermore, it is preferably 0.5 mm to 3 mm, more preferably 0.7 mm to 2 mm, and even more preferably 0.8 mm to 1.5 mm.

[0141] When the distance from the pressure chamber of the inkjet head to the nozzle is greater than or equal to the above range, it is preferable because it allows for greater design freedom in the positioning of the pressure chamber and nozzle within the inkjet head. On the other hand, when the distance from the pressure chamber of the inkjet head to the nozzle is greater than or equal to the above range, the following problems are likely to occur.

[0142] When ink flows through a narrow channel, such as a tubular tube, the surface of the scale-like metal pigment is oriented parallel to the direction of ink movement, causing the metal pigment to move along the channel. The particles move easily, which positively impacts ink ejection stability. However, when the metallic pigment becomes unstable in dispersion, the surface portions of the flaky metallic pigment tend to overlap and aggregate, resulting in coarse particles. When flaky metallic pigments are layered on a surface to form coarse particles, the orientation of the surfaces becomes less likely to align with the direction of ink movement, making movement difficult, and the particles no longer appear flaky. In such cases, the ink composition becomes difficult to circulate within the print head. This concern is particularly pronounced at high ejection frequencies. We suspect that the narrow, tube-like flow path from the pressure chamber to the nozzle of the inkjet print head is a factor that makes it difficult for such ink compositions to circulate.

[0143] However, since the ink composition used in the recording method of this embodiment contains a metal pigment treated with a specific phosphorus-based treatment agent, such a decrease in fluidity is less likely to occur, and stable ejection can be achieved even at high ejection frequencies.

[0144] 2.5.4.Circulation mechanism The recording device may have a circulation path for circulating the ink composition. Ink compositions containing metal pigments are prone to aggregation of metal pigments, which can easily cause clogging of the print head filter, but circulating the ink composition suppresses aggregation. In other words, aggregation is suppressed by circulating the ink composition to break up the aggregation of metal particles, or by mixing it with new ink supplied from a liquid container to dilute the aggregated metal particles. However, according to this embodiment, it is preferable that excellent ejection stability can be obtained even if the recording device does not have a circulation path. It is also preferable that the recording device does not necessarily require a circulation path.

[0145] The circulation path includes at least one of the following: a circulation return path that returns the ink composition from the ink channel that supplies the ink composition to the inkjet head, and a circulation return path that returns the ink composition from the inkjet head. Among these, a recording device that includes a circulation return path that returns the ink composition from the inkjet head is preferred.

[0146] In Figure 3, R represents a circulation return path provided in the inkjet head. The circulation return path R allows ink that was not ejected from the nozzle to flow out of the inkjet head. In the example in Figure 3, the circulation return path R is provided in the communication hole 127. A circulation return path R is provided for each pressure chamber. Ink that flows from the circulation return path R to the left in the figure is collected in an ink circulation chamber (not shown) via, for example, the circulation return path R provided for each pressure chamber, and then flows out of the inkjet head from the ink circulation chamber. In addition to being provided in the communication hole 127, the circulation return path R may also be provided in, for example, the pressure chamber.

[0147] Figure 4 is a diagram illustrating a recording device 1000, which is an example of a recording device. The recording device 1000 is an inkjet printing device that ejects an ink composition onto a recording medium M. The recording medium M is typically printing paper, but any recording medium made of any material such as resin film or cloth can be used as the recording medium M. As illustrated in Figure 4, the recording device 1000 is equipped with a liquid container 114 for storing the ink composition. For example, a cartridge that can be attached to the recording device 1000, a bag-shaped ink pack made of flexible film, or an ink tank that can be refilled with ink composition can be used as the liquid container 114. Multiple types of ink compositions with different colors may be stored in the liquid container 114. Ink may be supplied from the liquid container 114 to a sub-tank 115, and after accumulating ink in the sub-tank, it may be supplied to the inkjet head. Although not shown, a self-sealing valve is provided in the flow path through which ink is supplied from the sub-tank 115 to the inkjet head. Further downstream, a filter for capturing foreign matter may be provided.

[0148] As illustrated in Figure 4, the recording device 1000 comprises a control unit 200, a transport mechanism 220, a moving mechanism 240, and an inkjet head 100. The control unit 200 is, for example, For example, it includes processing circuits such as a CPU (Central Processing Unit) or FPGA (Field Programmable Gate Array) and storage circuits such as semiconductor memory, and comprehensively controls each element of the recording device 1000. The transport mechanism 220 transports the recording medium M in the Y direction under the control of the control unit 200.

[0149] The moving mechanism 240 reciprocates the inkjet head 100 in the X direction under the control of the control unit 200. The X direction intersects (typically orthogonal to) the Y direction in which the recording medium M is transported. The moving mechanism 240 comprises a roughly box-shaped transport body 242 (carriage) that houses the inkjet head 100 and a transport belt 244 to which the transport body 242 is fixed. Configurations in which multiple inkjet heads 100 are mounted on the transport body 242, or configurations in which a liquid container 114 is mounted on the transport body 242 together with the inkjet head 100, can also be adopted.

[0150] The inkjet head 100 ejects ink supplied from the liquid container 114 onto the recording medium M from multiple nozzles N (ejection holes) under the control of the control unit 200. Each inkjet head 100 ejects ink onto the recording medium M in parallel with the transport mechanism 220 and the repetitive reciprocating motion of the transport body 242, thereby forming a desired image on the surface of the recording medium M. The direction perpendicular to the XY plane (for example, a plane parallel to the surface of the recording medium M) will be referred to as the Z direction below. The direction of ink ejection from each inkjet head 100 (typically the vertical direction) corresponds to the Z direction.

[0151] As illustrated in Figure 4, the multiple nozzles N of the inkjet head 100 are arranged in the Y direction. The multiple nozzles N are divided into a first row L1 and a second row L2, which are spaced apart from each other in the X direction. Each of the first row L1 and the second row L2 is a collection of multiple nozzles N arranged linearly in the Y direction. It is also possible to have the positions of each nozzle N in the Y direction differ between the first row L1 and the second row L2 (i.e., staggered or stepped arrangement), but for convenience, the following example will illustrate a configuration in which the positions of each nozzle N in the Y direction are the same between the first row L1 and the second row L2. In the inkjet head 100, the plane O (YZ plane) that passes through the central axis parallel to the Y direction and is parallel to the Z direction will be referred to as the "center plane" in the following explanation.

[0152] The ink composition supplied from the sub-tank 115 to the inkjet head 100 is ejected from the nozzle hole N, but has a path for returning from the inkjet head 100 to the sub-tank 115. In other words, in the recording device 1000, the inkjet head 100 has a pressure chamber that applies pressure to the ink composition to eject it from the nozzle, and a circulation path that circulates the ink composition in the section from the pressure chamber to the nozzle. That is, the recording device 1000 has a circulation return path that returns the ink from the inkjet head 100.

[0153] The circulation return path in Figure 4 is a circulation return path that returns the ink that has flowed out of the inkjet head via the circulation return path in Figure 3 back to the sub-tank.

[0154] The ink that has returned to the sub-tank 115 is supplied again to the inkjet head 100. In this case, it is possible to circulate the ink both inside and outside the inkjet head 100, which is preferable because it further suppresses the occurrence of ink aggregation.

[0155] On the other hand, in Figure 4, the ink that flows through the ink channel from the sub-tank 115 toward the inkjet head 100 may not be supplied into the inkjet head 100, but instead branch off in an ink channel (not shown) before the inkjet head 100, becoming an ink channel that flows from the inkjet head 100 toward the sub-tank 115 and returns to the sub-tank 115. In this case, the channel that flows from the branching point toward the sub-tank 115 is a circulating return. This is a pathway. In other words, it is a circulating return path that returns ink from the ink channel that supplies ink to the inkjet head 100. In this case, there may be a circulation mechanism between the branching point and the sub-tank 115. In this case as well, it is possible to circulate the ink outside the inkjet head 100, and it is excellent in suppressing ink aggregation.

[0156] Furthermore, when we say that an inkjet recording device has a circulation path for circulating the ink composition, the circulation path in a broad sense refers to the entire part of the ink circulation system located between the sub-tank 115 and the inkjet head 100, or within the inkjet head 100, as shown in Figure 1. Also, the sub-tank 115 does not necessarily have to be a tank-shaped structure; it is sufficient to have a confluence point where the ink returned via the circulation return path and the ink discharged from the liquid container can merge.

[0157] 2.5.5. Recording media Examples of recording media used in the recording method include ink-absorbing recording media such as paper and fabric. These are recording media whose recording surface easily absorbs ink. Examples of paper include ordinary paper, inkjet-specific paper, and corrugated cardboard. Examples of fabrics include natural fibers such as cotton, polyester, and wool, as well as synthetic fibers and nonwoven fabrics.

[0158] Furthermore, the recording medium may be a non-absorbent recording medium made of plastic material, metal, glass, ceramics, wood, etc. This is a recording medium in which the recording surface does not easily absorb ink. Examples of recording media made of plastic material include plastic films and plastic sheets. Examples of plastics, though not limited to them, include polyvinyl chloride, polyester, and polyolefin. Examples of polyester include polyethylene terephthalate.

[0159] In addition, low-absorption recording media may be used. These are recording media whose recording surface has the second lowest absorption rate after non-absorbent recording media. Examples of low-absorption recording media include those having a coating layer (receiving layer) on the surface for receiving liquid, such as printing paper if the substrate is paper. The coating layer is one that does not easily absorb ink, and examples include those coated with particles such as inorganic compounds together with a binder.

[0160] Low-absorbent or non-absorbent recording media are recording media that do not absorb liquid at all or absorb very little liquid. For example, a non-absorbent or low-absorbent recording media is defined as "a recording medium that, in the Bristow method, is absorbed within 30 msec from the start of contact." 1 / 2 Up to 10 mL / m² of water absorption capacity 2 A recording medium that is one of the following is preferred.

[0161] The Bristow method is the most widely used method for measuring liquid absorption in a short time and is also adopted by the Japan Paper & Pulp Technology Association (JAPAN TAPPI). Details of the test method are described in standard No. 51 "Paper and cardboard - Liquid absorbency test method - Bristow method" of the "JAPAN TAPPI Paper & Pulp Test Methods 2000 Edition".

[0162] In contrast, absorbent recording media refer to recording media that do not fall under the categories of non-absorbent or low-absorbent.

[0163] Furthermore, the shape of the recording medium is not particularly limited and may be any form, such as a sheet, plate, or object.

[0164] 3. Examples and Comparative Examples The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. It is not meant to be done. Unless otherwise specified, percentages below refer to mass.

[0165] 3.1. Preparation of Ink Composition First, a 20 μm thick polyethylene terephthalate film with a smooth surface and a surface roughness Ra of 0.02 μm or less was prepared. Next, a release layer was formed on the entire surface of one side of this film by coating it with a release resin solubilized with acetone using a roll coater. The polyethylene terephthalate film with the release layer was transported into a vacuum deposition apparatus at a speed of 5 m / s, and a 15 nm thick film composed of Al was formed under reduced pressure.

[0166] Next, a polyethylene terephthalate film with an Al membrane formed on it was immersed in tetrahydrofuran, and ultrasonic vibrations at 40 kHz were applied to obtain a dispersion of Al metal particles.

[0167] Next, tetrahydrofuran was removed using a centrifuge, and diethylene glycol diethyl ether was added to obtain a suspension with a metal particle content of 5% by mass. The mass of the dispersant relative to the mass of the metal particles was 10% by mass.

[0168] Next, the suspension was treated with a circulating high-power ultrasonic grinder to grind the metal particles to a predetermined size. This process involved applying 20 kHz ultrasound.

[0169] Next, the suspension was subjected to heat treatment at 55°C for 2 hours under 40 kHz ultrasonic irradiation to break up the aggregation of metal particles and disperse them in a primary particle state. Then, the treatment agents listed in each table were added in a ratio such that the mass ratio to the metal particles was the value shown in the table.

[0170] Then, by heat treatment at 55°C for 5 hours under 28kHz ultrasonic irradiation, the treatment agent reacted on the surface of the metal particles, yielding a dispersion of metal pigment surface-modified with the treatment agent. In each case, a separate sample of this dispersion was taken for confirmation, and diethylene glycol diethyl ether was removed using a centrifuge. Upon confirmation of diethylene glycol diethyl ether, the presence of the surface treatment agent was not detected in any of the cases. From this, it is presumed that the surface treatment agent is adhering to the metal pigment.

[0171] The resulting dispersion of metal pigments was mixed with the organic solvents and binders shown in the table to obtain ink compositions 1 to 14. These were solvent-based compositions.

[0172] The volume-average particle size of the metal pigments contained in the ink compositions obtained in this manner is measured and shown in Tables 1 and 2. The volume-average particle size of the metal pigments in inks 5 and 6 was adjusted by changing the processing time in a circulating high-power ultrasonic grinder. The thickness of the metal pigments in inks 8 and 9 was adjusted by adjusting the amount of aluminum deposited during the aluminum vapor deposition process.

[0173] The formulations of the obtained inks 1 to 14 are shown in Tables 1 and 2.

[0174] [Table 1]

[0175] [Table 2]

[0176] The contents of each component in each ink composition are listed below.

[0177] Octyl phosphate (8 carbon atoms) (Tokyo Chemical Industries) Tridecyl phosphate (13 carbon atoms) (Tokyo Chemical Industries) Tetradecyl phosphate (14 carbon atoms) (Tokyo Chemical Industries) Octadecyl phosphonate (18 carbon atoms (Tokyo Chemical Industries)) • Stearyl phosphate (18 carbon atoms) (Tokyo Chemical Industries) • Tetracosyl phosphate (24 carbon atoms) (Tokyo Chemical Industries) Octadecyltrimethoxysilane (silane coupling agent) (Tokyo Chemical Industries) FAS13: 1H,1H,2H,2H-perfluorooctyltrimethoxysilane • FHP: 2-(perfluorohexyl)ethylphosphonic acid (Tokyo Chemical Industries) (8 carbon atoms) • DEDG: Diethylene glycol diethyl ether • BTGH: Tetraethylene glycol monobutyl ether ·γBL: γ-butyrolactone • Paraloid B60: Binder (acrylic resin, manufactured by Dow Chemical)

[0178] Regarding the metallic pigments, the volume-average particle size (D50) in the table was measured using a Microtrac MT-3300 (Microtrac-Bell, a laser diffraction / scattering particle size distribution analyzer). The thickness of the metallic pigments was measured using an atomic force microscope (nanonavi). E-sweep (manufactured by SII Corporation) The viscosity of each ink composition at 25°C, measured using a rotational viscometer in accordance with JIS Z8809, was within the range of 1.5 mPa·s to 15 mPa·s.

[0179] 3.2. Evaluation Method 3.2.1. Record Test A modified version of the Seiko Epson SC-S80650 was used, and the inks listed in Tables 3 to 5 were used for each example and comparative example. The nozzle diameter was set to 20 μm. The pressure chamber volume was set to 2900 pl. The flow path length from the pressure chamber to the nozzle in Figure 3 was the value shown in the table. In the examples with circulation in the table, the recording device was equipped with an ink circulation path as shown in Figures 3 and 4, and the ink was circulated during recording.

[0180] The inkjet head drive wave signal was set to the value shown in Figure 1, the ejection frequency was set to the value in the table, and the carriage speed was adjusted so that the dot density in the main scanning direction of one pass was 300 dpi. Multipass recording was performed, and the final image recording resolution was set to 600 x 600 dpi. The ink weight of the ink droplets was set to the value in the table.

[0181] The recording medium used was Mactac5829R, made of polyvinyl chloride (manufactured by Mactac). The surface temperature of the recording medium during ink application (primary heating step) was set to the values ​​shown in the table using a platen heater. In the reference example, the primary heating step was omitted. Furthermore, secondary heating was performed at 50°C using a secondary heating heater.

[0182] 3.2.2. Discharge stability (long term) For each case, continuous recording was performed for 10 hours. After recording, the nozzles were inspected, the occurrence rate of non-discharging nozzles was determined, and the results were evaluated according to the following criteria based on this occurrence rate and recorded in the table. A: 0% B: Over 0% and less than 1.0% C: 1.0% or more and less than 3.0% D: 3.0% or more and less than 6.0% E: 6.0% or more

[0183] 3.2.3. Dispensing stability after storage The ink from each example was placed in a container and stored at 60°C for 5 days, after which a 1-minute recording was made. After recording, the nozzles were inspected. The incidence rate of non-dispensing nozzles was determined, and based on this incidence rate, the following criteria were used for evaluation and recorded in the table. A: 0% B: Over 0% and less than 1.0% C: 1.0% or more and less than 3.0% D: 3.0% or more and less than 6.0% E: 6.0% or more

[0184] 3.2.4. Glossy (Initial) The recording pattern was recorded using ink before storage. After 24 hours at room temperature, the pattern was illuminated. The gloss was measured. A Konica Minolta GM-268A gloss meter was used to measure the gloss at 60°. The gloss was evaluated based on the results and the following evaluation criteria. A: 450 or more B: 400 or more, less than 450 C: 350 or more, less than 400 D: Less than 350

[0185] 3.2.5. Glossiness after storage A recording pattern was created using the ink stored at 60°C for 5 days as described above. The gloss of the pattern was measured after 24 hours at room temperature. The gloss was evaluated based on the results and the evaluation criteria below. A: 450 or more B: 400 or more, less than 450 C: 350 or more, less than 400 D: Less than 350

[0186] 3.2.6. Recording Speed For each example, the time required to record a 30cm x 30cm solid pattern was confirmed. The results were evaluated based on the following criteria, in comparison to Example 1 at 20kHz. A: The time taken to record was less than 100%. B: Time taken to record was between 100% and 140%. C: Time taken to record exceeded 140

[0187] 3.3. Evaluation Results The evaluation results are shown in Tables 3 to 5.

[0188] [Table 3]

[0189] [Table 4]

[0190] [Table 5]

[0191] Each of the recording methods in the embodiment, comprising an adhesion step of ejecting an ink composition containing a metal pigment in the form of flakes, whose surface is treated with a compound represented by formula (1) or formula (2), and an organic solvent from an inkjet head and adhering it to a recording medium, and a primary heating step of heating the recording medium during the adhesion step, wherein the ejection frequency of the ink composition is 15 kHz or higher, was found to have good ejection stability, produce colored materials with excellent image gloss, and have excellent recording speed.

[0192] In contrast, Comparative Examples 1-5 use an ink that is a compound represented by formula (1) or formula (2). It did not contain surface-treated metal pigments, resulting in poor ejection stability during long-term recording.

[0193] Comparative Examples 6 and 7 did not have a process with an ejection frequency of 15 kHz or higher, resulting in inferior recording speed. Although Comparative Example 7 did not contain a metal pigment whose surface was treated with a compound represented by formula (1) or formula (2), its ejection stability during long-term recording was not inferior. This indicates that ejection stability becomes an issue when the ejection frequency is high.

[0194] Reference Examples 1 and 2 lacked a primary heating step, and compared to cases with a primary heating step, the initial gloss tended to be lower. Reference Example 2 did not contain a metal pigment whose surface was treated with a compound represented by formula (1) or formula (2), but the ejection stability during long-term recording was not inferior. This indicates that ejection stability becomes an issue when a primary heating step is performed.

[0195] The embodiments and variations described above are merely examples and are not limited thereto. For example, each embodiment and each variation can be combined as appropriate.

[0196] The present invention includes configurations substantially identical to those described in the embodiments, for example, configurations with the same function, method, and results, or configurations with the same purpose and effect. Furthermore, the present invention includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. Furthermore, the present invention includes configurations that produce the same effects or achieve the same purpose as those described in the embodiments. Finally, the present invention includes configurations that add known technology to the configurations described in the embodiments.

[0197] The following can be derived from the embodiments and modifications described above.

[0198] The recording method is: An adhesion process in which the ink composition is ejected from the inkjet head and attached to the recording medium, The adhesion step includes a primary heating step for heating the recording medium, The adhesion step includes a step in which the ejection frequency of the ink composition is 15 kHz or higher. The aforementioned ink composition contains a metal pigment and a solvent component. The aforementioned solvent component includes an organic solvent. The aforementioned metal pigment is a flaky metal particle whose surface is treated with a compound represented by the following formula (1) or formula (2). (R 1 -)P(O)(OH)2···(1) (R 2 -O-) a P(O)(OH) 3-a ...(2) (In the formula, R 1 , R 2 (where a independently represents a hydrocarbon group having 14 or more carbon atoms, which may be substituted with substituents, and a represents 1 or 2.)

[0199] According to this recording method, even when using an ink composition containing flake-shaped metal pigments, the ink composition can be ejected from the inkjet head with good stability, and a recording with good gloss can be obtained, even when the process includes a high ejection frequency and a primary heating step.

[0200] In the above recording method, The average thickness of the metal pigment may be 30 nm or less.

[0201] This recording method is particularly effective in improving discharge stability, even when the metallic pigment has a shape that tends to reduce discharge stability. Furthermore, it allows for the production of recordings with superior metallic luster.

[0202] In the above recording method, The surface temperature of the recording medium in the primary heating step may be 30°C or higher and 50°C or lower.

[0203] This recording method is particularly effective in that it can improve discharge stability even when the process has steps that tend to reduce discharge stability.

[0204] In the above recording method, The volume-average particle size D50 of the metal pigment may be 0.5 μm or less.

[0205] This recording method allows for better discharge stability.

[0206] In the above recording method, The aforementioned ink composition may be a solvent-based ink or a water-based ink.

[0207] In the above recording method, The surface treatment agent may be present in an amount of 1% by mass or more and 50% by mass or less based on 100% by mass of the total mass of the metal particles.

[0208] This recording method allows for obtaining even better recordings of metallic luster.

[0209] In the above recording method, The aforementioned R 1 and R 2 This may be an unsubstituted hydrocarbon group.

[0210] This recording method allows for the creation of records with better water resistance.

[0211] In the above recording method, The aforementioned R 1 and R 2 This may be a hydrocarbon group having 15 to 30 carbon atoms.

[0212] This recording method provides even better dispersion stability for metal pigments.

[0213] In the above recording method, The aforementioned metal particles may consist of aluminum or an aluminum alloy.

[0214] This recording method allows for obtaining even better recordings of metallic luster.

[0215] In the above recording method, The aforementioned ink composition is a solvent-based ink. The organic solvent may be present in an amount of 60% by mass or more relative to the total amount of the ink composition.

[0216] This recording method allows the ink composition to dry quickly, enabling faster recording.

[0217] In the above recording method, The distance from the pressure chamber of the inkjet head to the nozzle may be 0.5 mm or more.

[0218] This recording method is particularly effective in improving ejection stability, even when the inkjet head has a structure that tends to reduce ejection stability.

[0219] In the above recording method, The inkjet head applies pressure to the ink composition and ejects it from the nozzle. The system may have a pressure chamber and a circulation path for circulating the ink composition in the section from the pressure chamber to the nozzle.

[0220] This recording method allows for recording even better discharge stability.

[0221] The recording device is An inkjet head that ejects the aforementioned ink composition, The system includes a primary heating mechanism that performs the primary heating step, Use one of the recording methods described above.

[0222] According to this recording device, even when using an ink composition containing flake-shaped metal pigments, the ink composition can be ejected from the inkjet head with good stability, even when the device has a high ejection frequency process and a primary heating process, resulting in a recording with good gloss. [Explanation of Symbols]

[0223] 1…Recording device, 2…Recording head, 3…IR heater, 4…Platen, 5…Heating heater, 6…Cooling fan, 7…Preheater, 8…Ventilation fan, 10…Nozzle plate, 12…Nozzle hole, 13…Nozzle surface, 20…Pressure chamber, 30…Diaphragm, 32…Piezoelectric element, 40…Ink supply chamber, 100…Inkjet head, 110…Communication plate, 120…Pressure chamber substrate, 126…Supply port, 127…Communication hole, 128…Discharge port, 132…Connection part, 140…Compliance sheet, 150…Cover, 114…Liquid container, 115…Sub-tank, 200…Control unit, 220…Conveying mechanism, 240…Moving mechanism, 242…Conveyor body, 244…Conveyor belt, 1000…Recording device, M…Recording medium

Claims

1. An adhesion process in which the ink composition is ejected from the inkjet head and attached to the recording medium, The adhesion step includes a primary heating step for heating the recording medium, The adhesion step includes a step in which the ejection frequency of the ink composition is 15 kHz or higher. The aforementioned ink composition contains a metal pigment and a solvent component. The aforementioned solvent component includes an organic solvent. A recording method wherein the metal pigment is in the form of flakes and is a metal particle whose surface is treated with a compound represented by the following formula (1) or formula (2). (R １ -)P(O)(OH) ２ ・・・(1) (R ２ -O-) ａ P(O)(OH) ３－ａ ・・・(2) (In the formula, R １ , R ２ (Independently, represents an unsubstituted hydrocarbon group with 14 or more carbon atoms, and a represents 1 or 2.)

2. In claim 1, A recording method wherein the average thickness of the metal pigment is 30 nm or less.

3. In claim 1 or claim 2, A recording method wherein the surface temperature of the recording medium in the primary heating step is 30°C or higher and 50°C or lower.

4. In any one of claims 1 to 3, A recording method wherein the volume-average particle diameter D50 of the metal pigment is 0.5 μm or less.

5. In any one of claims 1 to 4, A recording method wherein the ink composition is a solvent-based ink or a water-based ink.

6. In any one of claims 1 to 5, A recording method in which the surface of the metal particles is treated with a compound represented by formula (1) or formula (2) in an amount of 1% to 50% by mass based on 100% by mass of the total mass of the metal particles.

7. In any one of claims 1 to 6, Furthermore, a recording method comprising a post-heating step.

8. In any one of claims 1 to 7, The foregoing R １ and R ２ is a hydrocarbon group having 15 to 30 carbon atoms, recording method.

9. In any one of claims 1 to 8, A recording method wherein the metal particles consist of aluminum or an aluminum alloy.

10. In any one of claims 1 to 9, The aforementioned ink composition is a solvent-based ink. A recording method wherein the organic solvent is present in an amount of 60% by mass or more relative to the total amount of the ink composition.

11. In any one of claims 1 to 10, A recording method wherein the distance from the pressure chamber of the inkjet head to the nozzle is 0.5 mm or more.

12. In any one of claims 1 to 11, The inkjet head applies pressure to the ink composition and ejects it from the nozzle. A recording method having a pressure chamber and a circulation path for circulating the ink composition in the section from the pressure chamber to the nozzle.

13. An inkjet head that ejects the aforementioned ink composition, The system includes a primary heating mechanism that performs the primary heating step, A recording device that performs the recording method according to any one of claims 1 to 12.

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