JP2011089065A - Moisture content-reduced solvent ink composition, and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink composition capable of suppressing an unfavorable chemical reaction and suppressing a decrease in glossiness and the generation of gases even under a high-temperature environment; and to provide a method for producing the same. <P>SOLUTION: The method for producing a moisture content-reduced solvent ink composition comprises subjecting an ink composition containing a pigment dispersion containing a metal pigment and a dispersion medium, or the pigment dispersion and an organic solvent to a bubbling treatment for ≥4 hours using an inert gas containing a steam content of ≤2.0 mg/L, to thereby reduce a moisture content contained in the pigment dispersion or the ink composition. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a moisture content reducing solvent ink composition and a method for producing the same.

  In recent years, many applications of inkjet in printing have been seen, and one of the applications is metallic printing. For example, Japanese Patent Laid-Open No. 2002-179960 discloses a technique in which a metal film is formed on the surface of plastic spherical particles, and an ink composition containing the pigment is subjected to a printing process by ink jet printing (Patent Document 1). ). However, in order to obtain a high metallic luster, it is necessary to deform and flatten the sphere and smooth the surface. In this technique, it is said that it is necessary to simultaneously perform the press treatment with a roller and the heat treatment. Therefore, it is inevitable that the apparatus and the manufacturing process are complicated in this respect, and the recording medium is also limited.

  Japanese Patent Laid-Open No. 2003-292836 also discloses a technique using an ink composition in which a precious metal colloid such as gold or silver is dispersed (Patent Documents 2 and 3). However, when the noble metal colloid is prioritized in dispersion stability and the particle diameter is reduced to several nanometers to several tens of nanometers, color development derived from plasmon absorption appears, and a metallic luster cannot be obtained as an ink composition. In this case, after the coating film is dried, a metallic luster is obtained by fusing the colloidal particles by heat treatment at a temperature of 150 ° C. or higher. However, even with these techniques, even if a metallic luster is obtained, a high metallic specular luster having a specular gloss of 20 degrees, 60 degrees, and 85 degrees exceeding 200, 200, and 100, respectively, is obtained on a uniform and uniform surface. It was difficult. When the particle size is increased in favor of metallic luster, the dispersion stability is lowered, the problem of aggregation and sedimentation cannot be avoided, and the shelf life of the ink composition is remarkably reduced.

  The present inventors have proposed a technique described in Japanese Patent Application Laid-Open No. 2008-174712 as a pigment dispersion, an ink composition or the like that solves these problems (Patent Document 4).

JP 2002-179960 A Japanese Patent Laid-Open No. 2003-292836 JP 2003-306625 A JP 2008-174712 A

According to the technique described in Patent Document 4, an excellent ink composition can be provided from the viewpoint of having a high metallic mirror gloss. However, a large amount of moisture may be mixed in the pigment dispersion containing the metal pigment or the ink composition. In this case, the metal pigment is subjected to a chemical reaction such as oxidation or hydroxylation, or a chemical reaction that proceeds using water as an accelerator, that is, an oxidizing gas or an acid gas (SO _X , NO _X , CO _2, etc.) in the air. The reaction can corrode the surface and reduce gloss. In addition, when hydrogen gas is generated as a result of the chemical reaction, long-term storage in a sealed container becomes difficult. Since such a tendency becomes remarkable especially in a high temperature environment, there is room for improvement in the above technique.

  Accordingly, an object of the present invention is to provide an ink composition and a method for producing the same that can suppress an undesirable chemical reaction and can suppress a decrease in gloss and gas generation even under a high temperature environment.

  In order to solve the above-mentioned problems, the present inventors have intensively studied. As a result, the moisture contained in the pigment dispersion or ink composition is reduced by a bubbling treatment for a predetermined time, thereby suppressing the above-mentioned undesirable chemical reaction and reducing gloss or generating gas even in a high temperature environment. The knowledge that it can suppress was acquired. The present invention has been made on the basis of such knowledge, and provides the following inventions.

(1)
Bubbling treatment of a pigment dispersion containing a metal pigment and a dispersion medium or an ink composition containing the pigment dispersion and an organic solvent for 4 hours or more using an inert gas having a water vapor content of 2.0 mg / L or less. To reduce the amount of water contained in the pigment dispersion or the ink composition.
(2)
When the metal pigment is a tabular grain, the major axis in the major plane of the tabular grain is a, the minor axis is b, and the thickness of the tabular grain is d, the area of the major plane of the tabular grain The 50% average particle diameter R50 of the equivalent circle diameter determined from 0.5 to 3 μm, satisfying the condition of R50 / d> 5, and the maximum equivalent circle diameter determined from the area of the main plane of the tabular grains The method for producing a water content-reducing solvent ink composition according to (1), wherein the particle diameter Rmax is 10 μm or less.
(3)
The water content-reducing solvent ink composition according to (1) or (2), wherein the dispersion medium and / or the organic solvent contains one or more dispersion media and / or organic solvents that can be uniformly mixed with water. Production method.
(4)
The water content-reducing solvent ink composition according to any one of (1) to (3), wherein the dispersion medium and / or the organic solvent comprises a dispersion medium and / or an organic solvent that can be uniformly mixed with water. Method.
(5)
The dispersion medium and / or the organic solvent is any one of (1) to (4), which is a mixture of two or more selected from the group consisting of alkylene glycol diether, alkylene glycol monoether, and lactone. A method for producing a water content reducing solvent ink composition.

FIG. 2 is an exploded perspective view illustrating a configuration of a recording head. It is sectional drawing explaining the structure of an ink introduction needle | hook.

[Moisture content reducing solvent ink composition]
(Composition / Composition)
The water content reducing solvent ink composition according to an embodiment of the present invention includes a pigment dispersion containing a metal pigment (hereinafter referred to as “metallic pigment”) and a dispersion medium, and an organic solvent. The water content reducing solvent ink composition may contain a resin. The components constituting the water content reducing solvent ink composition will be described in detail later.

“Bubbling (treatment)” in the present invention refers to blowing a gas such as argon or nitrogen into a pigment dispersion or an ink composition solution. More specifically, a pipe for sending gas into the liquid phase in the container is provided in the liquid phase, while a pipe for sending gas out of the container is provided separately in the gas phase so as not to touch the liquid phase. , Refers to a process of foaming the solution by sending gas at a constant flow rate.
Further, the “pigment dispersion” and “ink composition” in the present invention mean a pigment dispersion and an ink composition, respectively, before the water content is reduced by bubbling. On the other hand, the “water content-reducing pigment dispersion” and the “water content-reducing solvent ink composition” in the present invention mean the pigment dispersion and the ink composition after the water content is lowered by bubbling.

(Production method)
The method for producing the water content-reducing solvent ink composition is included in the pigment dispersion or the ink composition by bubbling for 4 hours or more using an inert gas having a water vapor content of 2.0 mg / L or less. Including reducing the amount of moisture.
In the present invention, the pigment dispersion may or may not have a reduced water content. Specifically, by reducing the water content of at least one of the ink composition and the pigment dispersion contained in the composition, an ink composition that solves the above-described problems in the prior art is obtained as a result. It is done. Therefore, in the present invention, the “pigment dispersion or ink composition” that is the target for reducing the water content means “at least one of the pigment dispersion and the ink composition”.

Here, the significance of bubbling (processing) in the present embodiment will be described. Conventionally, water derived from an organic solvent that is a raw material of an ink composition is unavoidably mixed in the ink composition in an amount of about 0.2 to 0.3% by mass in the ink composition. Further, when the ink composition is manufactured, the composition absorbs moisture in the air, and as a result, about 0.5 to 0.7% by mass of moisture in the ink composition is unavoidable in the ink composition. It will be mixed.
Further, the ink composition may be exposed to a high temperature of at least about 40 to 50 ° C. in a transportation environment at the time of manufacture. Under such a temperature of about 40 to 50 ° C. or a high temperature exceeding 60 ° C., hydrogen gas is generated from the ink composition, and the ink composition may become a high temperature and cause a problem. This is because when a gas such as hydrogen gas is generated, the surface of the metal pigment is oxidized, the glossiness is lowered and the performance of the ink composition is deteriorated, and the printing characteristics are also deteriorated.

  On the other hand, the present inventors have found that the above problem does not occur by bubbling the pigment dispersion or the ink composition for a predetermined time using a predetermined inert gas. First, when an inert gas such as dry nitrogen gas is produced from liquid nitrogen, there is no room for moisture to be mixed, and there is almost no risk of moisture being mixed into the ink composition. Inert gases such as helium, neon, xenon and argon are also industrially supplied as high-purity gases, so that they contain only a negligible amount of moisture. In addition, since these inert gases are gases that do not contain oxygen, there is no risk that the organic solvent, which is the dispersion medium, is oxidized by bubbling to produce peroxides.

  Next, bubbling is performed in a non-heated system. By introducing a dry gas into the pigment, the amount of water contained in the ink composition after bubbling can be suppressed to about 0.1% by mass or less. . Furthermore, almost no gas remains in the ink composition, and the amount of dissolved gas in the composition is extremely low. Thus, the manufacturing method according to the present embodiment can suppress gas generation under a high temperature environment.

  The water content-reducing solvent ink composition can be produced by a known conventional method except that bubbling (treatment) is used as described above. For example, after first mixing a metallic pigment, a dispersant, and a liquid medium, which will be described later, a pigment dispersion is prepared by a ball mill, a bead mill, an ultrasonic wave, a jet mill, or the like as necessary, and desired ink characteristics are obtained. Adjust to have Subsequently, a binder resin, the liquid medium, and other additives (for example, a dispersion aid or a viscosity modifier) can be added with stirring to obtain an ink composition.

  In addition, the pigment raw material described later may be once subjected to ultrasonic treatment in a liquid medium to obtain a pigment dispersion, and then mixed with a necessary ink liquid medium. Alternatively, the pigment raw material can be directly subjected to ultrasonic treatment in an ink liquid medium to obtain an ink composition (including a water content-reducing solvent ink composition) as it is. Moreover, in order to adjust the solid content concentration in the ink composition (including the water content reducing solvent ink composition), a conventionally known method such as pressure filtration or centrifugal separation can be used.

  The removal of the water according to the present embodiment was performed by (i) preparing a pigment dispersion with a medialess type dispersing device such as the ultrasonic disperser or jet mill, and then (ii) obtaining the pigment ink composition. Thereafter, (iii) after obtaining the pigment dispersion, mixing the pigment dispersion with the ink solvent, and (iv) after applying the ultrasonic treatment to obtain an ink composition. It can be done in one or more stages.

(Physical properties)
The amount of water contained in the water content-reducing solvent ink composition obtained by the above production method or the water content-reducing pigment dispersion that is a component thereof is 0.7% by mass or less. Moreover, Preferably it is 0.65 mass% or less, More preferably, it is 0.6 mass% or less, More preferably, it is 0.5 mass% or less. When the amount is within the above range, the moisture content reducing solvent ink composition is excellent in high temperature stability, that is, the moisture content reducing solvent ink composition is capable of suppressing undesirable chemical reactions and suppressing gloss reduction and gas generation even in a high temperature environment. Things are obtained.

  In addition, although the measurement of the water content contained in the water content-reducing pigment dispersion or the water content-reducing solvent ink composition in the present specification is not particularly limited, for example, a trace moisture meter FM-300A manufactured by Ketto Scientific Laboratory Co., Ltd. Can be used.

  In addition, the physical properties of the water content-reducing solvent ink composition according to the present embodiment are not particularly limited. For example, the surface tension is preferably 20 to 50 mN / m. When the surface tension is less than 20 mN / m, the water content reducing solvent ink composition may spread or ooze out on the surface of the printer head for ink jet recording, which may make it difficult to eject ink droplets. On the other hand, when the surface tension exceeds 50 mN / m, the surface of the recording medium does not spread and may not be printed satisfactorily.

(Metallic pigment)
The metallic pigment in this embodiment is preferably produced by crushing a metal vapor-deposited film, and is preferably a tabular particle. In the following description, the major axis in the main plane of the tabular grain is a, the minor axis is b, and the thickness of the tabular grain is d.

A “tabular grain” refers to a grain having a substantially flat surface (main plane) and a substantially uniform thickness (d). Since the tabular particles are produced by crushing a metal vapor deposition film, metal particles having a substantially flat surface and a substantially uniform thickness can be obtained. Therefore, the major axis in the main plane of the tabular grains can be defined as a, the minor axis as b, and the thickness of the tabular grains as d.
The main plane can also be referred to as an elliptical surface defined by a major axis (a) and a minor axis (b).

  “Equivalent circle diameter” is the diameter of the circle when assuming that the main plane of the tabular grain of the metallic pigment is a circle having the same projected area as the projected area in the thickness (d) direction of the grain of the metallic pigment. is there. For example, when the main plane of the tabular grain of the metallic pigment is a polygon, the diameter of the circle obtained by converting the projection plane in the thickness (d) direction of the polygon into a substantially flat circle is This is called the equivalent circle diameter of the tabular grain of the metallic pigment.

The 50% average particle diameter R50 of the equivalent circle diameter determined from the area of the main plane of the tabular grains is preferably from 0.5 to 3 μm, preferably from 0.75 to 2 μm, from the viewpoint of metallic gloss and printing stability. More preferably. When the 50% average particle diameter R50 is less than 0.5 μm, the gloss is insufficient. On the other hand, when the 50% average particle diameter R50 exceeds 3 μm, the printing stability is lowered.
In addition to this, in the relationship between the 50% average particle diameter R50 of the equivalent circle diameter and the thickness d, it is preferable that R50 / d> 5 from the viewpoint of ensuring high metallic luster. When R50 / d is 5 or less, there is a problem that the metallic luster is insufficient.

  In addition, the maximum equivalent circle diameter Rmax obtained from the area of the main plane of the tabular grains is 10 μm or less from the viewpoint of preventing clogging of the water content reducing solvent ink composition in the ink jet recording apparatus. Is preferred. By setting Rmax to 10 μm or less, it is possible to prevent clogging of the nozzles of the ink jet recording apparatus and the mesh filter provided in the ink flow path.

  The metallic pigment is not particularly limited as long as it has a function such as metallic luster, but is preferably aluminum or an aluminum alloy, or silver or a silver alloy. Among these, aluminum or an aluminum alloy is preferable from the viewpoint of cost and ensuring a high metallic luster. When an aluminum alloy is used, the other metal element or non-metal element that can be added to aluminum is not particularly limited as long as it has a function such as having a metallic luster, but silver, gold, platinum, Examples thereof include nickel, chromium, tin, zinc, indium, titanium, copper, and the like, and at least one of these simple substances or alloys thereof and mixtures thereof is preferably used.

  The method for producing the metallic pigment includes, for example, a metal or alloy layer having a structure in which a release resin layer and a metal or alloy layer are sequentially laminated on a sheet-like substrate surface (hereinafter referred to as “pigment base”) and a release resin. Separating from the sheet-like substrate with the interface of the layers as a boundary, pulverizing and refining to obtain tabular grains. And it is preferable to fractionate the obtained tabular grains having a sphere-converted 50% average particle diameter (D50) of 0.8 to 1.2 μm by the light scattering method described later. Or, when the major axis in the main plane of the obtained tabular grain is a, the minor axis is b, and the thickness of the tabular grain is d, the equivalent circle diameter determined from the area of the main plane of the tabular grain It is preferable to fractionate those having a 50% average particle diameter R50 of 0.5 to 3 μm and satisfying the condition of R50 / d> 5.

Here, the 50% average particle diameter in terms of sphere by the light scattering method is specifically measured and derived as follows. In other words, by irradiating the particles in the dispersion medium with light, the diffracted and scattered light generated is measured by placing detectors at the front, side, and rear sites, and the distribution of the integrated percentage of the average particle diameter that is measured The point at which the curve intersects the horizontal axis of the cumulative percentage of 50% is defined as the above 50% average particle diameter.
In addition, the above average particle diameter in terms of sphere refers to an average particle diameter obtained from a measurement result on the assumption that particles that are originally indefinite are spherical. Examples of the measuring apparatus include a laser diffraction scattering type particle size distribution measuring device LMS-2000e manufactured by Seishin Enterprise Co., Ltd. When the 50% average particle diameter (D50) in terms of sphere by the light scattering method is within the above range, a coating film having a high metallic luster can be formed on the printed matter, and the ejection stability of the ink from the nozzles is also increased.

The major axis a, minor axis b, and equivalent circle diameter of the main plane of the metallic pigment (tabular grain) can be measured using a particle image analyzer. As the particle image analyzer, for example, flow type particle image analyzers FPIA-2100, FPIA-3000, and FPIA-3000S manufactured by Sysmex Corporation can be used.
The particle size distribution (CV value) of the metallic pigment (tabular particles) can be obtained by the following formula (1).
[Equation 1]
CV value = (standard deviation of particle size distribution / average value of particle diameter) × 100 (1)

  Here, the CV value obtained is preferably 60 or less, more preferably 50 or less, and still more preferably 40 or less. By selecting a metallic pigment having a CV value of 60 or less, the effect of excellent printing stability can be obtained.

  The metal or alloy layer is preferably formed by vacuum deposition, ion plating or sputtering.

  The thickness of the metal or alloy layer is preferably 5 nm to 100 nm, more preferably 20 nm to 100 nm. Thereby, a pigment having an average thickness of preferably 5 nm to 100 nm, more preferably 20 nm to 100 nm is obtained. By setting it to 5 nm or more, it is excellent in reflectivity and glitter, and the performance as a metallic pigment is enhanced. By setting it to 100 nm or less, increase in apparent specific gravity can be suppressed and dispersion stability of the metallic pigment can be secured. .

  The peeling resin layer in the pigment raw material is an undercoat layer of the metal or alloy layer, and is a peelable layer for improving the peelability from the sheet-like substrate surface. The resin used for the release resin layer includes a group consisting of polyvinyl alcohol, polyvinyl butyral, polyethylene glycol, polyacrylic acid, polyacrylamide, cellulose derivatives such as cellulose acetate butyrate (CAB), acrylic acid polymer, and modified nylon resin. One or more kinds of resins selected more are preferred.

  A solution containing the one or more resins is applied to a recording medium, and dried to form a layer. After coating, additives such as a viscosity modifier can be contained.

  The release resin layer is applied by generally used gravure coating, roll coating, blade coating, extrusion coating, dip coating, spin coating, or the like. After coating and drying, the surface is smoothed by calendaring if necessary.

  Although the thickness of the resin layer for peeling is not specifically limited, 0.5-50 micrometers is preferable, More preferably, it is 1-10 micrometers. If the thickness is less than 0.5 μm, the amount as a dispersion resin is insufficient.

  The sheet-like substrate is not particularly limited, but may be a polyester film such as polytetrafluoroethylene, polyethylene, polypropylene, or polyethylene terephthalate, a polyamide film such as 66 nylon or 6 nylon, a polycarbonate film, a triacetate film, a polyimide film, or the like. An example is a moldable film. A preferred sheet-like substrate is polyethylene terephthalate or a copolymer thereof.

  Although the thickness of these sheet-like base materials is not specifically limited, 10-150 micrometers is preferable. If it is 10 μm or more, there is no problem in handleability in the process or the like, and if it is 150 μm or less, it is rich in flexibility and there is no problem in roll formation, peeling and the like.

  Moreover, the said metal or alloy layer may be pinched | interposed with the protective layer so that it may illustrate in Unexamined-Japanese-Patent No. 2005-68250. Examples of the protective layer include a silicon oxide layer and a protective resin layer.

  The silicon oxide layer is not particularly limited as long as it is a layer containing silicon oxide, but is preferably formed from a silicon alkoxide such as tetraalkoxysilane or a polymer thereof by a sol-gel method.

  An alcohol solution in which the silicon alkoxide or a polymer thereof is dissolved is applied and heated and fired to form a silicon oxide layer coating film.

  The protective resin layer is not particularly limited as long as it is a resin that does not dissolve in the dispersion medium, and examples thereof include polyvinyl alcohol, polyethylene glycol, polyacrylic acid, polyacrylamide, and cellulose derivatives. Or it is preferable to form from a cellulose derivative.

  A layer obtained by applying an aqueous solution of one or a mixture of two or more of the above resins and performing drying or the like is formed. The coating solution can contain additives such as a viscosity modifier.

  The silicon oxide and the resin are applied by the same method as the application of the release resin layer.

  Although the thickness of the said protective layer is not specifically limited, The range of 50-150 nm is preferable. If it is less than 50 nm, the mechanical strength is insufficient, and if it exceeds 150 nm, the strength becomes too high, so that pulverization / dispersion becomes difficult, and peeling may occur at the interface with the metal or alloy layer.

  Further, as exemplified in JP-A-2005-68251, a color material layer may be provided between the protective layer and the metal or alloy layer.

  The color material layer is introduced to obtain an arbitrary colored composite pigment, and can contain a color material capable of imparting an arbitrary color tone and hue in addition to the metallic luster and glitter of the metallic pigment used in the present invention. If it is, it will not specifically limit. The color material used for the color material layer may be either a dye or a pigment. Moreover, as a dye and a pigment, a well-known thing can be used suitably.

  In this case, the “pigment” used in the color material layer means a natural pigment, a synthetic organic pigment, a synthetic inorganic pigment, or the like, which is defined in the field of general pigment chemistry. It is different from what is processed into a structure.

  A method for forming the color material layer is not particularly limited, but it is preferable to form the color material layer by coating.

  Moreover, when the color material used for a color material layer is a pigment, it is preferable that the color material dispersion resin is further included. As the color material dispersing resin, a pigment, a color material dispersing resin and other additives as necessary are dispersed or dissolved in a solvent, and after forming a uniform liquid film by spin coating as a solution, the resin is dried. The resin thin film is preferably prepared.

  In the production of the pigment raw material, it is preferable in terms of working efficiency that both the color material layer and the protective layer are formed by coating.

  The pigment base material may have a layer structure having a plurality of laminated structures of the release resin layer, a metal or alloy layer, and a protective layer. At that time, the total thickness of the laminated structure composed of a plurality of metal or alloy layers, that is, the metal or alloy layer excluding the sheet-like base material and the release resin layer immediately above it, the release resin layer, the metal or the alloy The thickness of the layer or the peeling resin layer-metal or alloy layer is preferably 5000 nm or less. When it is 5000 nm or less, even when the pigment raw material is rolled up, it is difficult to cause cracking and peeling, and is excellent in storage stability. In addition, when pigmented, it is excellent in glitter and preferable.

  Moreover, although the structure where the resin layer for peeling and the metal or alloy layer were laminated | stacked in order on both surfaces of the sheet-like base material surface is mentioned, it is not limited to these.

  Although it does not specifically limit as a peeling processing method from the said sheet-like base material, The following method is preferable. That is, a method in which a liquid (solvent) is jetted onto the pigment base material, and thereafter the metal or alloy layer of the base material is scraped and collected; a method in which the pigment base material is immersed in the liquid; In this method, ultrasonic treatment is simultaneously performed, and the peeling treatment and the grinding treatment of the peeled pigment are performed. According to these methods, in addition to the peeled metal or alloy layer, the liquid used for the peeling treatment can also be recovered. Examples of the liquid (solvent) used in such a peeling treatment method include glycol ether solvents or lactone solvents, or a mixture thereof.

  The method for pulverizing and refining the peeled metal or alloy layer is not particularly limited, and may be a conventionally known method using a ball mill, a bead mill, an ultrasonic wave or a jet mill. In this way, a metallic pigment is obtained.

  In the pigment obtained as described above, the release resin layer has a role of a protective colloid, and a stable dispersion can be obtained only by performing a dispersion treatment in a solvent. Further, in the water content reducing solvent ink composition using the pigment, the resin derived from the release resin layer also has a function of imparting adhesiveness to a recording medium such as paper.

In the present embodiment, the concentration of the metallic pigment in the water content reducing solvent ink composition is preferably 0.5 to 2% by mass when only one type of the ink is a metallic ink in the ink set. . Further, when the concentration of the metallic pigment in the water content reducing solvent ink composition is 0.5% by mass or more and less than 1.7% by mass, a half mirror is formed by ejecting an ink amount that cannot sufficiently cover the printing surface. A glossy surface like that, i.e., glossiness, is felt. Further, in such a case, it is possible to print a texture that allows the background to show through, and a high gloss metallic glossy surface can be formed by ejecting a sufficient amount of ink to cover the printing surface. Therefore, for example, it is suitable for forming a half mirror image on a transparent recording medium or for expressing a high gloss metal gloss surface.
Further, when the concentration of the metallic pigment in the water content reducing solvent ink composition is 1.7% by mass or more and 2.0% by mass or less, the metallic pigment is randomly arranged on the printing surface, and thus high gloss cannot be obtained. A matte metallic glossy surface can be formed. Therefore, for example, it is suitable for forming a shielding layer on a transparent recording medium.

  The dispersion medium contained in the pigment dispersion liquid (including the water content reduction pigment dispersion liquid) in the present embodiment is not particularly limited as long as the above-described metallic pigment can be dispersed. For example, glycol ethers such as diethylene glycol diethyl ether, triethylene glycol monobutyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, ethylene glycol monoallyl ether, ether acetates such as propylene glycol methyl ether acetate, γ-butyrolactone, etc. Examples include lactones and alcohols such as isopropyl alcohol.

(Organic solvent)
Although it does not specifically limit as an organic solvent in this embodiment, Preferably a polar organic solvent can be used. Examples of the polar organic solvent include, but are not limited to, alcohols (for example, methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, isopropyl alcohol, or fluorinated alcohol), ketones (for example, acetone, methyl ethyl ketone, Or cyclohexanone), carboxylic acid esters (eg, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, or ethyl propionate), or ethers (eg, diethyl ether, dipropyl ether, tetrahydrofuran, Alternatively, dioxane or the like can be used. These organic solvents may be used individually by 1 type, and may use 2 or more types together.

  When there are two or more organic solvents used in the water content-reducing solvent ink composition, the dispersion medium and / or the organic solvent is one or more dispersion media and / or organics that can be uniformly mixed with water. It is preferable to include a solvent. More preferably, the dispersion medium and / or the organic solvent comprises a dispersion medium and / or an organic solvent that can be uniformly mixed with water.

  Especially, it is preferable that the said organic solvent contains 1 or more types of alkylene glycol ether which is a liquid under normal temperature normal pressure.

  The alkylene glycol ether is based on aliphatic groups of methyl, n-propyl, i-propyl, n-butyl, i-butyl, hexyl, and 2-ethylhexyl, and allyl and phenyl groups having a double bond. There are ethylene glycol ethers and propylene glycol ethers. These are colorless and less odorous, and have ether groups and hydroxyl groups in the molecule, so that they are liquid components at room temperature having both characteristics of alcohols and ethers. Moreover, there are a monoether type in which only one hydroxyl group is substituted and a diether type in which both hydroxyl groups are substituted, and these can be used in combination.

  The organic solvent is preferably a mixture of two or more selected from the group consisting of alkylene glycol diether, alkylene glycol monoether and lactone.

  Examples of the alkylene glycol monoether include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, and diethylene glycol monoethyl ether. , Diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene Recall monoethyl ether, tetraethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether and the like.

Examples of the alkylene glycol diether include ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl 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 the like.
Moreover, alkylene glycol monoalkyl ether acetate can also be used as those derivatives. Examples of the alkylene glycol monoalkyl ether acetate include ethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol ether acetate, dipropylene monoethyl ether acetate and the like.

  Examples of the lactone include γ-butyrolactone, δ-valerolactone, and ε-caprolactone.

  By setting it as such a suitable structure, the objective of this invention can be achieved much more effectively and reliably.

(resin)
In this embodiment, examples of the resin that can be used in the water content reducing solvent ink composition include acrylic resins produced from acrylic esters and / or methacrylic esters, and styrene-acrylic copolymers of these with styrene. Resin, rosin modified resin, terpene resin, polyester resin, polyamide resin, epoxy resin, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer, fiber resin (for example, cellulose acetate butyrate, hydroxypropyl cellulose), polyvinyl Examples include butyral, polyacryl polyol, polyvinyl alcohol, and polyurethane.

  Non-aqueous emulsion type polymer fine particles (NAD = Non Aqueous Dispersion) can also be used as the resin. This is a dispersion in which fine particles such as polyurethane resin, acrylic resin and acrylic polyol resin are stably dispersed in an organic solvent.

  For example, examples of the polyurethane resin include Sanprene IB-501 and Sanprene IB-F370 manufactured by Sanyo Chemical Industries, Ltd. Moreover, as an acrylic polyol resin, Harima Kasei Co., Ltd. N-2043-60MEX is mentioned, for example.

  In order to further improve the fixability of the pigment to the recording medium, the resin emulsion is preferably added in an amount of 0.1% by mass or more and 10% by mass or less in the water content reducing solvent ink composition. If the addition amount is excessive, the printing stability cannot be obtained, and if it is too small, the fixing property is insufficient. From the same viewpoint, the concentration of the resin in the water content reducing solvent ink composition is preferably 0.05 to 1.5% by mass, more preferably 0.1 to 1.0% by mass, and 0 More preferably, it is 15-0.35 mass%, and it is especially preferable that it is 0.15-0.25 mass%.

  The resin in the water content reducing solvent ink composition is preferably at least one selected from the group consisting of polyvinyl butyral, cellulose acetate butyrate and polyacryl polyol, and more preferably cellulose acetate butyrate. preferable. By adopting such a suitable configuration, it is possible to obtain preferable effects such as good abrasion resistance at the time of drying, fixability and high metallic luster.

(Other ingredients)
The water content reducing solvent ink composition according to this embodiment preferably contains at least one glycerin, polyalkylene glycol, or saccharide. The total amount of the one or more types of glycerin, polyalkylene glycol, or saccharide is preferably added in an amount of 0.1% by mass or more and 10% by mass or less in the water content reducing solvent ink composition. With such a preferable configuration, it is possible to stabilize ink discharge and improve the image quality of the recorded matter while suppressing drying of the ink and preventing clogging.

  The polyalkylene glycol is a linear polymer compound having a repeating structure of an ether bond in the main chain, and is produced, for example, by ring-opening polymerization of a cyclic ether.

  Specific examples of the polyalkylene glycol include polymers such as polyethylene glycol and polypropylene glycol, ethylene oxide-propylene oxide copolymers and derivatives thereof. As the copolymer, any copolymer such as a random copolymer, a block copolymer, a graft copolymer, and an alternating copolymer can be used.

Preferable specific examples of the polyalkylene glycol include those represented by the following chemical formula (1).
[Chemical 1]
_{HO- (C n H 2n O)} m -H ··· (1)
(In the above formula, n represents an integer of 1 to 5, and m represents an integer of 1 to 100.)

In the above formula, (C _n H _2n O) _m may be one constant or a combination of two or more numbers within the range of the integer value n. For example, when n is 3, it is (C ₃ H ₆ O) _m , and when n is a combination of 1 and 4, it is (CH ₂ O—C ₄ H ₈ O) _m . Further, the integer value m may be one constant or a combination of two or more numbers within the range. For example, in the above example, when m is a combination of 20 and 40, it is (CH ₂ O) _20- (C ₂ H ₄ O) ₄₀ , and when m is a combination of 10 and 30, (CH ₂ O ) ₁₀ - _(a C ₄ H 8 _{O) 30.} Further, the integer values n and m may be arbitrarily combined within the above range.

  Examples of the saccharide include monosaccharides such as pentose, hexose, heptose, and octose; polysaccharides such as disaccharide, trisaccharide, and tetrasaccharide; and reduced derivatives such as sugar alcohol and deoxy acid that are derivatives thereof; aldonic acid and uron An oxidized derivative such as an acid; a dehydrated derivative such as glycosene; an amino acid; a thiosugar and the like. The polysaccharide refers to a saccharide in a broad sense and includes substances widely present in nature such as alginic acid, dextrin, and cellulose.

  The water content-reducing solvent ink composition according to the present embodiment preferably contains at least one acetylene glycol surfactant and / or silicone surfactant. The surfactant is preferably added in an amount of 0.05 to 0.3% by mass, more preferably 0.2 to 0.3% by mass, based on the total amount of the water content reducing solvent ink composition. More preferred.

  By adopting such a suitable configuration, the affinity (wetting property) of the moisture content reducing solvent ink composition to the recording medium is improved, and quick fixability can be obtained.

  Examples of the acetylene glycol surfactant include Surfynol 465 (trademark), Surfhinol 104 (trademark) (manufactured by Air Products and Chemicals, Inc.), Olfine STG (trademark), and Olfine E1010 (trademark) ( As mentioned above, trade names, manufactured by Nissin Chemical Co., Ltd.) and the like are preferable.

  As the silicone surfactant, polyester-modified silicone or polyether-modified silicone is preferably used. Specific examples include BYK-347, BYK-348, BYK-UV3500, BYK-UV3570, BYK-UV3510, and BYK-UV3530 (Bic Chemie Japan Co., Ltd.).

  As described above, according to the present embodiment, there is provided a water content-reducing solvent ink composition and a method for producing the same, which can suppress undesirable chemical reactions and can suppress a decrease in gloss and gas generation even under a high temperature environment. It becomes possible to do.

[Ink set]
An ink set according to an embodiment of the present invention includes a plurality of the water content reducing solvent ink compositions, and each of the water content reducing solvent ink compositions has a different metallic pigment concentration.
Among the water content-reducing solvent ink compositions, the concentration of the metallic pigment of at least one water content-reducing solvent ink composition is 0.5% by mass or more and less than 1.0% by mass, and at least one other water content. The concentration of the metallic pigment in the amount-reducing solvent ink composition is preferably 1.0% by mass or more and 2.0% by mass or less.

[Ink container]
The ink container according to the embodiment of the present invention is, for example, an ink storage container or an ink cartridge described later. When the ink container is employed, the water content reducing solvent ink composition stored therein and / or the water content reducing pigment dispersion contained in the water content reducing solvent ink composition is 4 hours or more in advance. It is preferable that the water content is reduced by the bubbling treatment.

[Recording device]
A recording apparatus according to an embodiment of the present invention is an inkjet recording apparatus including the ink set.

  The configuration of the recording head 3 of the ink jet recording apparatus will be described. Here, FIG. 1 is a schematic perspective view of the recording head 3 accommodated in a carriage (not shown). FIG. 2 is a cross-sectional view of the ink introduction needle 19 inserted into the ink cartridge.

  The exemplified recording head 3 has a cartridge base 15 (hereinafter referred to as “base”). A head case 16 is attached to the base 15. A flow path unit 17 is attached (arranged) to the tip of the head case 16. The base 15 is formed of, for example, synthetic resin, and a plurality of compartments 15a (liquid storage member mounting portions) are provided on the upper surface thereof.

  An ink introduction needle 19 is attached to each compartment 15a with a mesh filter 18 interposed therebetween. An ink cartridge (not shown) is attached to these compartments 15a. That is, the ink cartridge is disposed on the base 15. Details of the ink introduction needle 19 inserted into the ink cartridge will be described later.

  A circuit board 20 is attached to the other surface of the base 15 on the side opposite to the section 15a. And this circuit board 20 is attached to the base 15 via the sheet | seat member 21 which functions as packing.

  The head case 16 is fixed to the base 15 and is a casing for housing the vibrator unit 22 having a piezoelectric vibrator. And the flow path unit 17 is being fixed to the front end surface on the opposite side to the attachment surface of the base 15 of the head case 16 with the adhesive agent. The flow path unit 17 is manufactured by sequentially laminating the elastic plate 23, the flow path forming substrate 24, and the nozzle plate 25, and fixing and integrating them with an adhesive or the like.

  Here, the nozzle plate 25 is a plate-like member made of, for example, a stainless steel thin plate, and fine nozzle openings 26 are formed in a row at a pitch corresponding to the dot formation density of the printer. Moreover, the head cover 27 is comprised by the metal thin plate member, for example.

  As shown in FIG. 2, the ink introduction needle 19 inserted into the ink cartridge is a hollow needle having an upstream end formed in a conical shape and an ink introduction path 41 formed therein, and a lower half portion. Is formed in a tapered shape that expands from the upstream side toward the downstream side. In addition, an ink introduction hole 42 that connects the external space and the ink introduction path 41 is formed at the distal end side of the ink introduction needle 19.

  The ink introduction needle 19 is attached to the base 15 by ultrasonic welding, for example, with the mesh filter 18 shown in FIG. 1 interposed. As a result, the ink introduction path 41 of the ink introduction needle 19 and the ink communication path 37 of the head case 16 communicate with each other.

  When an ink cartridge (not shown) is attached to the compartment 15 a of the base 15, the ink introduction needle 19 is inserted into the needle insertion port of the ink cartridge, and the ink cartridge inner space and the ink introduction path in the ink introduction needle 19 are inserted. 41 communicates with the ink through holes 42. Thereafter, the ink stored in the ink cartridge is introduced into the ink introduction path 41 through the ink introduction hole 42 and ejected from the nozzle opening 26 through the ink communication path 37.

  When the diameter of the nozzle opening 26 of the recording head 3 of the ink jet recording apparatus is L μm and the opening of the mesh filter 18 provided in the ink introduction path 41 is W μm, the nozzle diameter L μm and the opening W μm of the mesh filter are Preferably satisfies the relationship of L ≧ 5W. When the water content-reducing solvent ink composition of this embodiment is used in an ink jet recording apparatus that satisfies such a relationship, clogging of the metallic pigment at the nozzle opening 26 is prevented, and the ejection stability of the water content-reducing solvent ink composition is prevented. From the viewpoint of securing the properties, the following conditions are preferable. That is, when the average particle diameter of the equivalent circle diameter obtained from the area of the main plane of the tabular grains is R μm, the number of tabular grains satisfying the condition of R> (L / 5) is 5 of the total number of tabular grains. % Or less is preferable.

[Inkjet recording method]
An ink jet recording method according to an embodiment of the present invention performs recording by ejecting droplets of the water content reducing solvent ink composition and attaching the droplets to a recording medium.
From the viewpoint of angle dependency, the measured values of 20 °, 60 °, and 85 ° specular gloss on the recording medium according to JIS Z8741 have a metallic luster that indicates values of 200, 200, 100 or more at the same time, respectively. It is preferable to form an image. More preferably, the measured values of 20 °, 60 ° and 85 ° specular gloss specified in JIS Z8741 are 400, 400 and 100 or more at the same time, respectively. More preferably, the measured values of 20 °, 60 °, and 85 ° specular gloss specified in JIS Z8741 are 600, 600, and 100 or more at the same time, respectively.
JIS Z8741 (Established date: March 30, 1959, revised date: September 20, 1997) is a JIS regulation concerning a method for measuring specular gloss. The specular glossiness is expressed as a percentage of the reflected light at the same angle with respect to the incident light on the surface, that is, the specular reflected light with respect to the reflected light under the same condition on the reference surface. That is, the degree of surface gloss is expressed. For example, the glossiness measured at an incident angle of 60 degrees and a reflection angle of 60 degrees with respect to the normal is referred to as a 60-degree specular glossiness. Further, a glass plane having a refractive index of 1.567 is used as a reference surface for specular gloss.

  Images with measured values of 20 °, 60 °, and 85 ° specular gloss specified in JIS Z8741 that are simultaneously 200 or more and less than 400, 200 or more and less than 400, and 100 or more are matte. Has a metallic luster.

  Images with measured values of 20 °, 60 °, and 85 ° specular gloss specified in JIS Z8741 of 400 or more and less than 600, 400 or more and less than 600, and 100 or more are reflected in the formed image. It has a high and excellent metallic luster so that the object can be discriminated slightly.

  An image having a metallic luster in which the measured values of 20 °, 60 °, and 85 ° specular gloss specified in JIS Z8741 are simultaneously 600 or more, 600 or more, and 100 or more has sharpness. The image has a gloss so that an object reflected in the formed image can be clearly distinguished, that is, a metallic gloss having a so-called “specular gloss”.

  Therefore, according to the ink jet recording method of the present embodiment, the measured values of 20 °, 60 °, and 85 ° specular gloss on the recording medium are 200, 200, and 100 or more simultaneously, respectively. An image having a metallic luster that indicates is appropriately combined. Accordingly, an image having a desired metallic luster can be formed from a matte tone image to a glossy image.

  On the other hand, when the measured values of 20 °, 60 °, and 85 ° specular gloss do not show values of 200, 200, and 100 or more, such images do not feel metallic gloss when visually observed, and are gray. As observed. In addition, the effect of the present invention cannot be obtained even when any of the measured values of 20 °, 60 °, and 85 ° specular gloss does not show a value greater than or equal to the above value.

The discharge amount of the water content-reducing solvent ink composition discharged onto the recording medium is preferably 0.1 to 100 mg / cm ² from the viewpoint of securing metallic luster, the viewpoint of the printing process, and the cost. 1.0 to 50 mg / cm ² is more preferable.

The dry weight of the metallic pigment that forms an image on the recording medium is preferably 0.0001 to 3.0 mg / cm ² from the viewpoint of metallic gloss, printing process, and cost. The lower the dry weight of the metallic pigment, the more glossy metallic surface can be formed. Therefore, for example, it is suitable for forming a half mirror image on a transparent recording medium.
Further, the higher the dry weight of the metallic pigment, the more matte metallic glossy surface can be formed. Therefore, for example, it is suitable for forming a shielding layer on a transparent recording medium.

  Examples of the method for discharging the moisture content reducing solvent ink composition include the methods described below.

  As a first method, there is an electrostatic suction method. In this method, a strong electric field is applied between the nozzle and the accelerating electrode placed in front of the nozzle, ink is continuously ejected from the nozzle in the form of droplets, and a print information signal is output while the ink droplets fly between the deflection electrodes. Is applied to the deflection electrode for recording. Alternatively, this method is a method in which ink droplets are ejected in response to a print information signal without being deflected.

The second method is a method in which ink droplets are forcibly ejected by applying pressure to the ink liquid with a small pump and mechanically vibrating the nozzle with a crystal resonator or the like. The ejected ink droplet is charged simultaneously with the ejection, and a printing information signal is given to the deflection electrode and recorded while the ink droplet flies between the deflection electrodes.

  The third method is a method using a piezoelectric element (piezo element), in which pressure and a print information signal are simultaneously applied to an ink liquid by a piezoelectric element to eject and record ink droplets.

  The fourth method is a method in which the ink liquid is rapidly expanded in volume by the action of heat energy, and the ink liquid is heated and bubbled by a microelectrode in accordance with a print information signal to eject and record ink droplets.

  Any of the above methods can be used in the ink jet recording method of the present embodiment. However, from the viewpoint of high-speed printing, it is preferable that the method of discharging the moisture content reducing solvent ink composition is a non-heating method. . That is, it is preferable to employ the first method, the second method, or the third method.

  The recording medium is not particularly limited, and is a plain paper, inkjet paper (matte paper, glossy paper), glass, plastic film such as PVC, film with a base material coated with plastic or receiving layer, metal, printed wiring board, etc. Various recording media can be used.

  When the recording medium has an ink receiving layer, it is preferable to print the recording medium without heating from the viewpoint of not causing thermal damage.

  On the other hand, when the recording medium does not have an ink receiving layer, it is preferable to print by heating the recording medium from the viewpoint of increasing the drying speed and obtaining high gloss.

  Heating is performed by bringing a recording medium into contact with a heat source, heating without irradiating the recording medium by irradiating infrared rays or microwaves (electromagnetic waves having a maximum wavelength of about 2,450 MHz), or blowing hot air. The method etc. are mentioned.

  The heating is preferably performed at least one of the timing before printing, at the same time as printing, and after printing. In other words, the recording medium may be heated before printing, simultaneously, or after printing, and may be heated throughout printing. The heating temperature depends on the type of the recording medium, but is preferably 30 to 80 ° C, more preferably 40 to 60 ° C.

  According to the ink jet recording method of the present embodiment, since the above-described water content-reducing solvent ink composition is used, the water content-reducing solvent ink composition suppresses the above-described undesirable chemical reaction, and even under a high temperature environment. Gloss reduction and gas generation can be suppressed.

[Recordings]
A recorded matter according to an embodiment of the present invention is a medium on which an ink composition is to be ejected, which has been recorded by the inkjet recording method. Since this recorded matter was obtained by the ink jet recording method using the ink set described above, it has excellent printing stability. Further, it is possible to obtain a recorded matter having a high metal specular gloss, in which the specular gloss values of 20 degrees, 60 degrees, and 85 degrees indicate numerical values of 200, 200, and 100 or more, respectively. In addition, since the metallic pigment concentration of the water content-reducing solvent ink composition provided in the ink set varies depending on each water content-reducing solvent ink composition, it is possible to simultaneously form any metallic luster from specular gloss to matte tone. .

(1. Preparation of metallic pigment dispersion)
A resin layer coating solution comprising 3% by mass of cellulose acetate butyrate (butylation rate of 35 to 39%, manufactured by Kanto Chemical Co., Ltd.) and 97% by mass of diethylene glycol diethyl ether (manufactured by Nippon Emulsifier Co., Ltd.) on a PET film having a thickness of 100 μm. Was applied uniformly by a bar coating method. And the resin layer thin film was formed on PET film by drying at 60 degreeC for 10 minute (s).

  Next, the aluminum vapor deposition layer with an average film thickness of 20 nm was formed on said resin layer using the vacuum vapor deposition apparatus (VE-1010 type vacuum vapor deposition apparatus by a vacuum device company).

  Next, the laminate formed by the above method is simultaneously peeled, refined, and dispersed in diethylene glycol diethyl ether using a VS-150 ultrasonic disperser (manufactured by ASONE), and integrated ultrasonic dispersion treatment. A metallic pigment dispersion having a time of 8 hours was prepared.

  The obtained metallic pigment dispersion was filtered with a SUS mesh filter having an opening of 5 μm to remove coarse particles. Subsequently, the filtrate was put into a round bottom flask, and diethylene glycol diethyl ether was distilled off using a rotary evaporator. Thus, the metallic pigment dispersion was concentrated, and then the concentration of the metallic pigment dispersion was adjusted to obtain a metallic pigment dispersion having a concentration of 5% by mass.

(2. Preparation of metallic pigment ink composition)
A metallic pigment ink composition having the composition shown in Table 1 was prepared using the metallic pigment dispersion prepared by the above method. The solvent and additives were mixed and dissolved to obtain an ink solvent. Thereafter, the metallic pigment dispersion was added to the ink solvent, and further mixed and stirred with a magnetic stirrer at room temperature and normal pressure for 30 minutes to obtain a metallic pigment ink composition.

  Diethylene glycol diethyl ether (DEGdEE) and tetraethylene glycol dimethyl ether (TEGDM) manufactured by Nippon Emulsifier Co., Ltd. were used. Further, γ-butyrolactone was manufactured by Kanto Chemical. Tetraethylene glycol monobutyl ether (TEGMB) manufactured by Nippon Emulsifier Co., Ltd. was used. Cellulose acetate butyrate (CAB) was manufactured by Kanto Chemical Co. (butylation rate of 35 to 39%), and BYK-UV3500 (surfactant) was manufactured by Big Chemie Japan. The unit is mass%.

(3. Bubbling process)
300 mL of each of the metallic pigment dispersion or the ink composition was put into a trap three-necked flask (capacity: 500 mL) manufactured by AS ONE Corporation. Then, 99.5% by mass or more of dry nitrogen having a water vapor content of 0.2 mg / L or less was adjusted with a regulator so that the flow rate was 500 mL / min. Then, what was connected to Kerami filter B type φ10 × 180 manufactured by AS ONE through a transparent tube having excellent gas barrier properties was placed in the trap three-necked flask. In this way, as shown in Table 2, the metallic pigment dispersion or the ink composition was bubbled for a predetermined time using dry nitrogen as an inert gas (Examples 1 to 3).

  As a comparative example, as shown in Table 2, in the case of no bubbling (Comparative Example 1), air of 25 ° C.-50% relative humidity (RH) was used instead of dry nitrogen, and 500 mL / min via a compressor. Evaluation was also performed when bubbling was performed at a flow rate of (Comparative Example 2).

(4. Heat resistance evaluation test)
After the above bubbling, the moisture-reducing solvent ink composition, which was allowed to stand for 24 hours or more to remove air bubbles, was transferred to a three-side sealed bag made of a multilayer film consisting of a polyester film, an aluminum vapor deposition film, and a polyethylene film. 30 g of the composition was added. The three-side sealed bag was heat-sealed so as not to contain air bubbles and sealed to obtain an ink storage container (seal pack).

The water vapor transmission rate of this multilayer film was 0.01 g / m ² · day as measured by PERMATRAN / W manufactured by Hitachi High-Technologies Corporation.

  The storage container was allowed to stand for 1 week in an environment of 40 ° C., 50 ° C., and 60 ° C., and then it was confirmed whether or not bubbles were generated due to gas generation. The confirmation method was performed by sucking out the contents in the ink storage bag using a Terumo Corporation 50 mL syringe SS-50LZ and visually confirming the presence or absence of bubbles. The case where no bubble is visually observed is good “A”, the case where the volume of the generated bubble is less than 1 cc is good “B”, and the case where the volume of the generated bubble is 1 cc or more is impossible “C”. It was.

  Moreover, it evaluated also about the metallic pigment dispersion liquid on the same conditions as said Examples 1-3 and Comparative Examples 1-3. The results are shown in Examples 4 to 6 and Comparative Examples 4 to 6, respectively.

  As described above, it has been clarified that bubbling with dry nitrogen significantly improves the heat resistance of the metallic pigment dispersion and the ink composition, that is, the ability to suppress gas generation even under a high temperature environment.

(5. Glossiness evaluation test)
100 g of the ink composition was put in a three-sided seal bag made of a multilayer film composed of three layers of a polyester film, an aluminum vapor deposition film, and a polyethylene film under the same conditions as in the examples and comparative examples shown in Table 5 below. . And it heat-sealed so that a bubble might not be included, and it sealed, and the heat storage test of the ink storage container (seal pack) for 40 degreeC-5 days and 65 degreeC-5 days was done (reference example, Example 7- 12, Comparative Examples 7-12). Thereafter, each ink composition was filled into a black row using an ink jet printer EM-930C (manufactured by Seiko Epson Corporation). Then, solid printing was performed on the A4-sized photographic paper <Glossy> (product number: KA4100PSKR) manufactured by Seiko Epson Corporation in a room temperature environment using the high-definition mode. The glossiness was measured using a gloss meter GM-286 manufactured by Konica Minolta. The reference example corresponds to the control experimental group. The results are shown in Table 5 below.

  Although Examples 7-12 which reduced moisture content showed the high glossiness similar to the reference example which is a control experiment, even after a heat resistance test, moisture content was reduced completely or almost. It was found that the gloss values of the comparative examples 7 to 12 which were not decreased significantly.

  From the above results, it has been clarified that the water content contained in the ink composition and its constituent metallic pigment dispersion can be significantly reduced by bubbling with a predetermined inert gas for a predetermined time. . Further, it was found that the water content-reducing solvent ink composition having such a reduced water content is excellent in high-temperature stability of 40 ° C. or higher, that is, gas generation suppression performance in a high-temperature environment. Furthermore, it has also been clarified that printed matter printed using these water content-reducing solvent ink compositions exhibits good gloss.

  DESCRIPTION OF SYMBOLS 3 ... Recording head, 15 ... Base, 15a ... Section, 16 ... Head case, 17 ... Flow path unit, 18 ... Mesh filter, 19 ... Ink introduction needle, 20 ... Circuit board, 21 ... Sheet member, 22 ... Vibrator Unit: 23 ... elastic plate, 24 ... flow path forming substrate, 25 ... nozzle plate, 26 ... nozzle opening, 27 ... head cover, 37 ... ink communication port, 41 ... ink introduction path, 42 ... ink introduction hole.

Claims (5)

  Bubbling treatment of a pigment dispersion containing a metal pigment and a dispersion medium or an ink composition containing the pigment dispersion and an organic solvent for 4 hours or more using an inert gas having a water vapor content of 2.0 mg / L or less. To reduce the amount of water contained in the pigment dispersion or the ink composition. When the metal pigment is a tabular grain, the major axis in the major plane of the tabular grain is a, the minor axis is b, and the thickness of the tabular grain is d, the area of the major plane of the tabular grain The 50% average particle diameter R50 of the equivalent circle diameter determined from 0.5 to 3 μm, satisfying the condition of R50 / d> 5, and the maximum equivalent circle diameter determined from the area of the main plane of the tabular grains The method for producing a water content-reducing solvent ink composition according to claim 1, wherein the particle diameter Rmax is 10 μm or less.   The method for producing a water content-reducing solvent ink composition according to claim 1 or 2, wherein the dispersion medium and / or the organic solvent contains one or more kinds of dispersion medium and / or organic solvent that can be uniformly mixed with water. .   4. The production of a water content-reducing solvent ink composition according to claim 1, wherein the dispersion medium and / or the organic solvent comprises a dispersion medium and / or an organic solvent that can be uniformly mixed with water. Method.   The said dispersion medium and / or the said organic solvent are 2 or more types of mixtures selected from the group which consists of alkylene glycol diether, alkylene glycol monoether, and lactone, The any one of Claims 1-4. A method for producing a water content-reducing solvent ink composition.

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