JP5975205B2 - Ink composition for inkjet printer - Google Patents

Description

  The present invention relates to a water-resistant aluminum pigment dispersion, a method for producing the same, and an aqueous ink composition.

  Conventionally, as a method of forming a coating film having a metallic luster on a printed material, gold powder produced from brass, aluminum fine particles, etc., printing ink using silver powder as a pigment, foil press printing using metal foil, metal foil was used. Thermal transfer systems have been used.

  In recent years, there have been many examples of application to inkjet in printing, and one of them is metallic printing, and development of ink having metallic luster has been promoted. For example, Patent Document 1 discloses an aluminum pigment dispersion based on an organic solvent such as alkylene glycol and a non-aqueous ink composition containing the same.

  On the other hand, from the viewpoint of the global environment and the safety to the human body, there is an actual situation that development of an aqueous ink composition is desired rather than a non-aqueous ink composition based on an organic solvent. However, when the aluminum pigment is dispersed in water, it generates hydrogen gas by reaction with water and forms alumina to whiten. Thereby, an aluminum pigment may impair metallic luster.

  In order to solve such a problem, for example, Patent Document 2 discloses that a raw material aluminum pigment includes (1) Si-containing compound, (2) water, (3) a hydrophilic organic solvent, and (4) phosphoric acid and / or phosphorus. A silica-coated aluminum pigment obtained by contacting a reaction solution containing an acid salt as an essential component is disclosed. According to this silica-coated aluminum pigment, it is excellent in storage stability when blended in a water-based paint, and it is possible to suppress deterioration of gloss (metallic feeling) of the coating film.

JP 2008-174712 A JP 2002-088274 A

  However, the silica-coated aluminum pigment disclosed in Patent Document 2 described above is still insufficient from the viewpoint of suppressing aggregation of aluminum pigments. For example, when an aqueous ink composition containing a silica-coated aluminum pigment disclosed in Patent Document 2 is applied to an ink jet printer, nozzle clogging occurs due to aggregation of the aluminum pigments, resulting in ink ejection stability. May be damaged. From this point of view, not only the storage stability when blended in an aqueous paint or aqueous ink composition is good, but also the dispersion stability in an aqueous paint or aqueous ink composition (hereinafter referred to as “water dispersibility”). There is also a demand for an aluminum pigment that is excellent in that.

  Some embodiments according to the present invention can prevent whitening when blended in a water-based paint or water-based ink composition by solving the above-mentioned problems, have excellent metallic gloss, water dispersibility and A water-resistant aluminum pigment dispersion having particularly good storage stability and a method for producing the same are provided.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

（式（１）中、ＡＯはオキシアルキレン基を表し、Ｒは置換基を有してもよい炭素数５〜３０の炭化水素基を表し、ｎは５〜３５の整数を表す。） [Application Example 1]
One aspect of the water resistant aluminum pigment dispersion according to the present invention is:
A water-resistant aluminum pigment dispersion in which a water-resistant aluminum pigment whose surface is coated with a silica film is dispersed in an aqueous medium,
It contains a compound represented by the following general formula (1).

(In Formula (1), AO represents an oxyalkylene group, R represents a C5-C30 hydrocarbon group which may have a substituent, and n represents an integer of 5-35.)

[Application Example 2]
In the water resistant aluminum pigment dispersion of Application Example 1,
In the general formula (1), R may further have an unsaturated bond.

[Application Example 3]
In the water-resistant aluminum pigment dispersion of Application Example 1 or Application Example 2,
The content ratio of the compound represented by the general formula (1) may be 0.05 parts by mass or more and 2.5 parts by mass or less with respect to 1 part by mass of the water-resistant aluminum pigment.

[Application Example 4]
In the water-resistant aluminum pigment dispersion of any one of Application Examples 1 to 3,
Furthermore, a tertiary amine can be contained.

[Application Example 5]
In the water resistant aluminum pigment dispersion of Application Example 4,
The content ratio of the tertiary amine may be 0.05 parts by mass or more and 2.5 parts by mass or less with respect to 1 part by mass of the water resistant aluminum pigment.

[Application Example 6]
In the water-resistant aluminum pigment dispersion of any one of Application Examples 1 to 5,
The aluminum pigment may be a tabular grain having an average thickness of 5 nm to 30 nm and a 50% average particle diameter of 0.5 μm to 3 μm.

（式（１）中、ＡＯはオキシアルキレン基を表し、Ｒは置換基を有してもよい炭素数５〜３０の炭化水素基を表し、ｎは５〜３５の整数を表す。） [Application Example 7]
One aspect of the method for producing a water-resistant aluminum pigment dispersion according to the present invention is as follows:
A step (a) of preparing an aluminum pigment dispersion in which an aluminum pigment is dispersed in an organic solvent;
Adding tetraethoxysilane to the aluminum pigment dispersion; and (b)
Separating the aluminum pigment having a silica film formed on the surface thereof from the aluminum pigment dispersion (c);
A step (d) of dispersing an aluminum pigment having a silica film formed on the surface thereof in an aqueous solution containing a compound represented by the following general formula (1);
including.

(In Formula (1), AO represents an oxyalkylene group, R represents a C5-C30 hydrocarbon group which may have a substituent, and n represents an integer of 5-35.)

[Application Example 8]
One aspect of the water-based ink composition according to the present invention is:
The water-resistant aluminum pigment dispersion of any one of Application Examples 1 to 6 is contained.

[Application Example 9]
In the water-based ink composition of Application Example 8,
Furthermore, a tertiary amine can be contained.

  Hereinafter, preferred embodiments of the present invention will be described. The embodiment described below describes an example of the present invention. In addition, the present invention is not limited to the following embodiments, and includes various modifications that are implemented within a range that does not change the gist of the present invention.

  Hereinafter, a method for producing a water-resistant aluminum pigment dispersion, a water-resistant aluminum pigment dispersion, a water-resistant aluminum pigment, and a water-based ink composition will be described in this order.

（式（１）中、ＡＯはオキシアルキレン基を表し、Ｒは置換基を有してもよい炭素数５〜３０の炭化水素基を表し、ｎは５〜３５の整数を表す。）
以下、前述した各工程について詳細に説明する。 1. Method for Producing Water-Resistant Aluminum Pigment Dispersion A method for producing a water-resistant aluminum pigment dispersion according to the present embodiment includes the step (a) of preparing an aluminum pigment dispersion in which an aluminum pigment is dispersed in an organic solvent, and A step (b) of adding tetraethoxysilane to the aluminum pigment dispersion, a step (c) of separating an aluminum pigment having a silica film formed on the surface thereof from the aluminum pigment dispersion, and a silica film being formed on the surface And a step (d) of dispersing the obtained aluminum pigment in an aqueous solution containing a compound represented by the following general formula (1).

(In Formula (1), AO represents an oxyalkylene group, R represents a C5-C30 hydrocarbon group which may have a substituent, and n represents an integer of 5-35.)
Hereinafter, each process mentioned above is demonstrated in detail.

1.1. Step (a)
Step (a) is a step of preparing an aluminum pigment dispersion in which an aluminum pigment is dispersed in an organic solvent.

  First, a composite pigment base having a structure in which a release resin layer and an aluminum or aluminum alloy layer (hereinafter simply referred to as “aluminum layer”) are sequentially laminated on a sheet-like substrate surface is prepared.

  Although it does not restrict | limit especially as a sheet-like base material, Polytetrafluoroethylene, polyethylene, polypropylene, Polyester films, such as a polyethylene terephthalate, Polyamide films, such as nylon 66 and nylon 6, Polycarbonate films, a triacetate film, a polyimide film, etc. A functional film. Of these, polyethylene terephthalate or a copolymer thereof is preferable.

  The thickness of the sheet-like substrate is not particularly limited, but is preferably 10 μm or more and 150 μm or less. 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.

  The release resin layer is an undercoat layer of an aluminum layer, and is a peelable layer for improving the peelability from the sheet-like substrate surface. As the resin used for the release resin layer, for example, polyvinyl alcohol, polyvinyl butyral, polyethylene glycol, polyacrylic acid, polyacrylamide, cellulose derivative, acrylic acid polymer, or modified nylon resin is preferable.

  The resin layer for peeling can be formed by applying a solution of one or two or more of the resins exemplified above to a sheet-like substrate and drying it. After coating, additives such as a viscosity modifier can be added.

  For the application of the release resin layer, commonly used techniques such as gravure coating, roll coating, blade coating, extrusion coating, dip coating, and spin coating can be used. After coating and drying, the surface can be smoothed by calendaring if necessary.

  The thickness of the release resin layer is not particularly limited, but is preferably 0.5 μm or more and 50 μm or less, and more preferably 1 μm or more and 10 μm or less. If it is less than 0.5 μm, the amount as a dispersion resin is insufficient, and if it exceeds 50 μm, when it is rolled, it tends to peel off at the interface with the pigment layer.

  As means for laminating the aluminum layer, it is preferable to apply vacuum deposition, ion plating or sputtering.

  The aluminum layer may be sandwiched between protective layers as exemplified in JP-A-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. A coating film of a silicon oxide layer can be formed by applying an alcohol solution in which silicon alkoxide or a polymer thereof is dissolved, followed by heating and baking.

  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. Of these, it is preferably formed from polyvinyl alcohol or a cellulose derivative.

  A protective resin layer can be formed by applying and drying an aqueous solution of one or more of the above exemplified resins. Additives such as a viscosity modifier can be further added to the coating solution. The silicon oxide and the resin are applied by the same method as the application of the release resin layer.

  The thickness of the protective layer is not particularly limited, but is preferably in the range of 50 nm to 150 nm. 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 aluminum layer.

  Moreover, as illustrated in US Pat. No. 7,303,619, the composite pigment base may have a color material layer between the protective layer and the aluminum layer.

  The color material layer is introduced to obtain an arbitrary colored composite pigment, and in addition to the metallic luster, glitter, and background hiding properties of the aluminum pigment used in the present embodiment, a color that can impart an arbitrary color tone and hue. There is no particular limitation as long as the material can be contained. As the color material used for this color material layer, either a dye or a pigment may be used. Moreover, as a dye and a pigment, a well-known thing can be used suitably.

  In such a case, the “pigment” used in the color material layer means a natural pigment, a synthetic organic pigment, a synthetic inorganic pigment or the like defined in the general engineering field.

  The method for forming the color material layer is not particularly limited, but is preferably formed by coating. Further, when the color material used in the color material layer is a pigment, it is preferable to further include a color material dispersion resin. Examples of the color material dispersion resin include a pigment, a color material dispersion resin, and other materials as necessary. It is preferable that the additive is dispersed or dissolved in a solvent to form a uniform liquid film by spin coating as a solution and then dried to produce a resin thin film. In the production of the composite pigment raw material, it is preferable in terms of work efficiency that both the colorant layer and the protective layer are formed by coating.

  As the composite pigment base material, a layer structure having a plurality of sequentially laminated structures of a release resin layer and an aluminum layer is also possible. At that time, the total thickness of the laminated structure composed of a plurality of aluminum layers, that is, excluding the sheet-like substrate and the peeling resin layer immediately above the aluminum layer-the peeling resin layer-the aluminum layer or the peeling resin layer- The thickness of the aluminum layer is preferably 5000 nm or less. When it is 5000 nm or less, even when the composite pigment base material is rolled up, it is difficult to cause cracking and peeling and is excellent in storage stability. Moreover, it is excellent also in the metal glossiness when it is pigmented. Moreover, although the structure where the peeling resin layer and the aluminum layer were laminated | stacked one by one on both surfaces of the sheet-like base material surface is mentioned, it is not restrict | limited to these.

  Next, the composite pigment base material is peeled from the composite pigment base material in an organic solvent at the interface between the sheet base surface of the composite pigment base material and the release resin layer as a boundary, and then pulverized or refined. By processing, an aluminum pigment dispersion containing coarse particles is obtained. Furthermore, the obtained aluminum pigment dispersion is filtered to remove coarse particles, whereby an aluminum pigment dispersion containing aluminum tabular particles can be obtained.

  Any organic solvent may be used as long as it does not impair the dispersion stability of the aluminum pigment and the reactivity with tetraethoxysilane described later, but a polar organic solvent is preferable. Examples of polar organic solvents include alcohols (methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, isopropyl alcohol, fluorinated alcohol, etc.), ketones (acetone, methyl ethyl ketone, cyclohexanone, etc.), carboxylic acid esters (methyl acetate, Ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, etc.), ethers (diethyl ether, dipropyl ether, tetrahydrofuran, dioxane, etc.) and the like.

  Among the polar organic solvents exemplified above, alkylene glycol monoether or alkylene glycol diether which is liquid at normal temperature and pressure is more preferable.

  As alkylene glycol monoether, 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, 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, propylene glycol monomethyl ether, propylene group 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, tetra Ethylene 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, etc. It is below.

  Among these, triethylene glycol monobutyl ether and diethylene glycol diethyl ether are more preferable from the viewpoint of excellent dispersion stability of the aluminum pigment.

  The peeling treatment method from the sheet-like substrate is not particularly limited, but is a method that is performed by immersing the composite pigment raw material in a liquid, or the ultrasonic treatment is performed at the same time as the immersion in the liquid. A method of pulverizing the composite pigment thus obtained is preferred.

  The aluminum pigment composed of tabular grains obtained as described above has a release resin layer serving as a protective colloid, and a stable dispersion can be obtained simply by performing a dispersion treatment in an organic solvent. It is.

  The aluminum pigment in the aluminum pigment dispersion obtained by the above process becomes tabular grains. It is preferable that the aluminum pigment is a tabular particle in that good metallic luster is easily obtained. Here, the term “tabular particle” refers to an aluminum particle having a substantially flat surface (XY plane) when the major axis on the plane is X, the minor axis is Y, and the thickness is Z. (Z) refers to particles that are substantially uniform. More specifically, the 50% average particle diameter R50 (hereinafter also simply referred to as “R50”) of the equivalent circle diameter determined from the area of the substantially flat surface (XY plane) of the aluminum particles is 0.5 μm or more and 3 μm. And the thickness (Z) satisfies 5 nm or more and 30 nm or less. The thickness Z means an average thickness and is an average value obtained by performing the measurement 10 times.

  The “equivalent circle diameter” is the diameter of the circle when assuming that the substantially flat surface (XY plane) of the aluminum particles is a circle having the same projected area as the projected area of the aluminum particles. For example, when the substantially flat surface (XY plane) of an aluminum particle is a polygon, the diameter of the circle obtained by converting the polygonal projection surface into a circle is the equivalent circle diameter of the aluminum particle. That's it.

  The 50% average particle diameter R50 of the equivalent-circle diameter determined from the area of the substantially flat surface (XY plane) of the tabular grains is preferably from the viewpoint of ensuring good metal gloss and printing stability. It is preferably 5 μm or more and 3 μm or less, and more preferably 0.75 μm or more and 2 μm or less. If the R50 is within the above range, particularly the lower limit value or more, the metallic gloss tends to be good, and if it is less than the upper limit value, the printing stability tends to be good.

  The major axis X, minor axis Y, and equivalent circle diameter on the plane of the tabular grain can be measured using a particle image analyzer. Examples of the particle image analyzer include a flow type particle image analyzer FPIA-2100, FPIA-3000, and FPIA-3000S (manufactured by Sysmex Corporation).

The particle size distribution (CV value) of the tabular grains can be obtained from the following formula (2).
CV value = standard deviation of particle size distribution / average value of particle size × 100 (2)

  Here, the CV value obtained is preferably 60 or less, more preferably 50 or less, and particularly preferably 40 or less. By selecting tabular grains having a CV value of 60 or less, an effect of excellent printing stability can be obtained.

  The thickness (Z) is preferably 5 nm or more and 30 nm or less, more preferably 10 nm or more and 25 nm or less, from the viewpoint of securing metallic gloss. When the thickness (Z) is within the above range, even if a silica film is formed on the surface of the aluminum pigment, the metallic gloss tends to be good without being impaired.

  The aluminum pigment is preferably aluminum or an aluminum alloy from the viewpoint of cost and ensuring the metallic luster. In the case of using an aluminum alloy, examples of other metal elements or non-metal elements added in addition to aluminum include silver, gold, platinum, nickel, chromium, tin, zinc, indium, titanium, and copper.

  In addition, you may provide separately the process of wash | cleaning the aluminum pigment contained in the aluminum pigment dispersion liquid obtained by said process. The organic solvent mentioned above can be used for washing | cleaning of an aluminum pigment.

  The aluminum pigment dispersion may contain the aforementioned release resin layer, or the release resin layer may adhere to the aluminum pigment. The component contained in the release resin layer may inhibit the reaction between tetraethoxysilane and an aluminum pigment, which will be described later. Therefore, by washing the aluminum pigment, the components of the peeling resin layer can be removed, and the reactivity between tetraethoxysilane and the aluminum pigment, which will be described later, can be improved.

  Although it does not specifically limit as a washing | cleaning method of an aluminum pigment, For example, it can carry out by the following methods.

  First, at least a part of the organic solvent is removed from the aluminum pigment dispersion. For removing the organic solvent, the organic solvent and the aluminum pigment are separated by an operation such as filtration, centrifugal sedimentation, or centrifugal separation to remove the organic solvent contained in the aluminum pigment dispersion.

  Next, an organic solvent for washing is added to the aluminum pigment to disperse the aluminum pigment in the organic solvent, and then the organic solvent for washing is removed. The operation of dispersing the aluminum pigment in the cleaning organic solvent and removing the cleaning organic solvent may be performed a plurality of times.

  Thereafter, an aluminum pigment dispersion containing the washed aluminum pigment can be obtained by adding and dispersing the above-described organic solvent to the aluminum pigment.

1.2. Step (b)
Step (b) is a step of adding tetraethoxysilane (hereinafter also referred to as “TEOS”) to the aluminum pigment dispersion obtained in step (a) and stirring. By adding TEOS and stirring sufficiently, the hydroxyl groups present on the surface of the aluminum pigment and the silanol groups of TEOS are hydrolyzed and condensed to form a silica film on the surface of the aluminum pigment. By forming a silica film on the surface of the aluminum pigment, it is possible to prevent the aluminum pigment and water from coming into direct contact with each other, so that water resistance can be imparted to the aluminum pigment.

  The reaction temperature in the hydrolysis condensation is preferably 10 ° C. or higher and 150 ° C. or lower, more preferably 20 ° C. or higher and 130 ° C. or lower. If the reaction temperature is in the above range, particularly the lower limit value or more, the reaction rate of the hydrolysis condensation is good without slowing too much, and if it is not more than the upper limit value, it can be reacted easily without safety problems. .

  The reaction time in the hydrolysis condensation is preferably 0.5 hours or more and 200 hours or less, more preferably 1 hour or more and 180 hours or less. If the reaction time is within the above range, particularly the lower limit value or more, hydrolysis condensation can be completed sufficiently, so that an aluminum pigment having sufficient water resistance can be obtained, and if the reaction time is less than the upper limit value, the aluminum pigment aggregates. This can be suppressed.

  The amount of TEOS added may be determined by calculating an amount such that the thickness of the silica film is 0.5 nm to 10 nm, preferably 1 nm to 9 nm, more preferably 2 nm to 8 nm, and particularly preferably 5 nm. . This is because if the thickness of the silica film exceeds 10 nm, the metallic gloss may be lowered.

  More specifically, the addition amount of TEOS is preferably 0.2 parts by mass or more and 5 parts by mass or less, and 0.5 parts by mass or more and 4 parts by mass or less with respect to 1 part by mass of the aluminum pigment. Is more preferable, and it is particularly preferably 1 part by mass or more and 3 parts by mass or less. When the addition amount of TEOS exceeds 5 parts by mass, unreacted TEOS may form independent silica particles, which may cause the aluminum pigment dispersion to become cloudy. On the other hand, if it is less than 0.2 parts by mass, the hydroxyl group present on the surface of the aluminum pigment may not be completely hydrolytically condensed.

  In step (b), after addition of TEOS, a basic catalyst may be further added to promote hydrolysis and condensation. Examples of the basic catalyst include ammonia, trialkylamine, ethanolamine, sodium hydroxide, potassium hydroxide, urea, choline, tetraalkylammonium hydroxide, and the like. Among these, ammonia is particularly preferable.

  The addition amount of the basic catalyst is preferably 1 part by mass or less, more preferably 0.1 part by mass or less, with respect to 10 parts by mass of the aluminum pigment. If the addition amount of the basic catalyst exceeds the above range, the viscosity of the aluminum pigment dispersion may increase, or the aluminum pigment in the aluminum pigment dispersion may aggregate and the metallic luster may not be maintained.

1.3. Step (c)
Step (c) is a step of separating an aluminum pigment having a silica film formed on the surface (hereinafter also referred to as “water-resistant aluminum pigment”) from the aluminum pigment dispersion obtained in step (b).

  The means for separating the water-resistant aluminum pigment is not particularly limited, for example, by separating the water-resistant aluminum pigment and other organic solvent by an operation such as filtration, centrifugal sedimentation or centrifugation, A means for removing components other than the water-resistant aluminum pigment contained in the aluminum pigment dispersion obtained in the step (b) is mentioned.

（式（１）中、ＡＯはオキシアルキレン基を表し、Ｒは置換基を有してもよい炭素数５〜３０の炭化水素基を表し、ｎは５〜３５の整数を表す。） 1.4. Step (d)
Step (d) is a step of adding and dispersing the water resistant aluminum pigment obtained in step (c) in an aqueous solution containing a compound represented by the following general formula (1). Through the step (d), the compound represented by the following general formula (1) is introduced into at least one of the surface and the inside of the silica film formed on the surface of the aluminum pigment, and the water-dispersed aluminum pigment is dispersed in water. (That is, aggregation of water resistant aluminum pigments can be suppressed).

(In Formula (1), AO represents an oxyalkylene group, R represents a C5-C30 hydrocarbon group which may have a substituent, and n represents an integer of 5-35.)

In the general formula (1), AO represents an oxyalkylene group. Among the oxyalkylene groups, an oxyethylene group (—OCH ₂ CH ₂ —), an oxypropylene group (—OCH ₂ CH ₂ CH ₂ — or —OCH ₂ CH (CH ₃ ) —) is preferable. AO may be only an oxyethylene group, only an oxypropylene group, or may contain both an oxyethylene group and an oxypropylene group. When AO contains both an oxyethylene group and an oxypropylene group, the constituent ratio and arrangement are not particularly limited.

  In the said General formula (1), although n represents the integer of 5-35, it is preferable that it is an integer of 6-25, and it is more preferable that it is an integer of 8-19. When n is in the above range, the balance between hydrophilicity and hydrophobicity is improved, so that the solubility of the compound represented by the general formula (1) in water is improved and the surface active action is effective. Can be expressed. If the surface active action can be effectively expressed, the compound represented by the general formula (1) can be easily introduced into at least one of the surface and the inside of the silica film.

  In the general formula (1), the hydrocarbon group represented by R may be linear or branched. The hydrocarbon group represented by R is preferably an aliphatic hydrocarbon group. Moreover, the hydrocarbon group represented by R may have a substituent. Examples of such a substituent include a hydroxy group, an alkoxy group, a carboxyl group, a carbonyl group, an amino group, an imino group, a cyano group, an azo group, a thiol group, a sulfo group, a nitro group, and a halogen. Among these, the substituent is preferably a hydroxy group.

  The hydrocarbon group represented by R preferably has one or more unsaturated bonds, and the unsaturated bond is more preferably a carbon-carbon double bond. The position and number of unsaturated bonds in the hydrocarbon group represented by R are not particularly limited. Although the detailed mechanism is not clear, it has been found that when the hydrocarbon group represented by R has one or more unsaturated bonds, the water dispersibility of the water-resistant aluminum pigment can be further improved.

  In the said General formula (1), although carbon number of the hydrocarbon group which R represents is 5-30, 10-24 are preferable, 15-20 are more preferable, and 16-18 are especially preferable.

  First, an aqueous solution in which the compound represented by the general formula (1) is completely dissolved is prepared by adding the compound represented by the general formula (1) to an aqueous medium and sufficiently stirring. At this time, the compound represented by the general formula (1) may be synthesized and added in advance, but a commercially available product containing the compound represented by the general formula (1) may be added. As a commercial item containing the compound represented by the said General formula (1), BYK series (made by Big Chemie Japan Co., Ltd.) is mentioned.

  Hereinafter, suitable specific examples of the compound represented by the general formula (1) will be given. Preferred specific examples include a compound of the following formula (3) in which oxyethylene group is added using ricinoleic acid as a raw material, a compound of formula (4) in which oxyethylene group is added using linoleic acid as a raw material, and linolenic acid as a raw material. Examples thereof include a compound of the following formula (5) to which an oxyethylene group is added and a compound of the following formula (6) to which an oxyethylene group is added using stearic acid as a raw material. In the following formula, n represents an integer of 5 to 35, preferably an integer of 6 to 25, and more preferably an integer of 8 to 19.

  The aqueous medium may be a medium containing water as a main component. It is preferable to use pure water or ultrapure water such as ion exchange water, ultrafiltered water, reverse osmosis water, or distilled water. In particular, water obtained by sterilizing these waters by ultraviolet irradiation or addition of hydrogen peroxide is preferable because generation of mold and bacteria can be suppressed over a long period of time.

  The content of the compound represented by the general formula (1) is preferably 0.05 parts by mass or more and 2.5 parts by mass or less, and 0.1 parts by mass with respect to 1 part by mass of the water resistant aluminum pigment. More preferably, it is 2 parts by mass or less. When the content ratio of the compound represented by the general formula (1) is within the above range, an effect of improving the water dispersibility of the water-resistant aluminum pigment is easily obtained.

  Further, it is preferable to add a tertiary amine to the aqueous medium. By adding a tertiary amine, it is considered that the following two effects can be obtained, and the water dispersibility of the water-resistant aluminum pigment can be further improved.

  As a first effect, the liquid property of the water resistant aluminum pigment dispersion can be made basic by adding a tertiary amine. In general, aluminum tends to react with water because it is acidic. Therefore, it is considered that the water resistant aluminum pigment can be prevented from reacting with water by making the liquid resistance of the water resistant aluminum pigment dispersion basic. Thereby, since a water-resistant aluminum pigment is stabilized, it is thought that water dispersibility can be improved further.

  As a second effect, it is considered that the tertiary amine is adsorbed to the silanol group present on the surface of the silica film because the nitrogen atom of the tertiary amine is positively charged. The tertiary amine has a bulky structure. Therefore, it is considered that the water-resistant aluminum pigment adsorbed with the tertiary amine can further improve the water dispersibility due to the steric hindrance effect of the tertiary amine.

  The tertiary amine is preferably water-soluble from the viewpoint of dissolution in an aqueous medium. Examples of such a water-soluble tertiary amine include triethanolamine, tripropanolamine, tributanolamine, N, N-dimethyl-2-aminoethanol, N, N-diethyl-2-aminoethanol, and the like. Of the hydroxylamine. Among these, triethanolamine and tripropanol are preferable in terms of further improving water dispersibility, and triethanolamine is more preferable in terms of improving storage stability in addition to water dispersibility.

  The content of the tertiary amine is preferably 0.05 parts by mass or more and 2.5 parts by mass or less, and 0.1 parts by mass or more and 2 parts by mass or less with respect to 1 part by mass of the water resistant aluminum pigment. It is more preferable. When the content ratio of the tertiary amine is within the above range, the above-described effect can be efficiently exhibited, and thus the effect of improving the water dispersibility of the water resistant aluminum pigment is easily obtained.

  Next, the water resistant aluminum pigment separated in the step (c) is added to an aqueous solution in which the compound represented by the general formula (1) is completely dissolved, and the mixture is sufficiently stirred. The stirring time is not particularly limited, but is preferably 3 hours or more and 120 hours or less. When the stirring time is within the above range, a water-resistant aluminum pigment dispersion having excellent water dispersibility can be obtained without impairing the metallic luster.

  By passing through the steps (a) to (d) as described above, whitening can be prevented when blended in a water-based paint or water-based ink composition, and it has excellent metallic gloss, water dispersibility and A water-resistant aluminum pigment dispersion having particularly good storage stability can be produced.

2. Water-Resistant Aluminum Pigment Dispersion The water-resistant aluminum pigment dispersion according to the present embodiment is obtained by the above-described manufacturing method and has the following characteristics.

（式（１）中、ＡＯはオキシアルキレン基を表し、Ｒは置換基を有してもよい炭素数５〜３０の炭化水素基を表し、ｎは５〜３５の整数を表す。） That is, the water-resistant aluminum pigment dispersion according to the present embodiment is a water-resistant aluminum pigment dispersion in which a water-resistant aluminum pigment whose surface is coated with a silica film is dispersed in an aqueous medium. It contains a compound represented by the formula (1).

(In Formula (1), AO represents an oxyalkylene group, R represents a C5-C30 hydrocarbon group which may have a substituent, and n represents an integer of 5-35.)

  According to the water-resistant aluminum pigment dispersion according to the present embodiment, water resistance is imparted by forming a silica film on the surface of the aluminum pigment, so that when it is blended in a water-based paint or water-based ink composition It can prevent whitening and has excellent metallic luster. Moreover, since the compound represented by the above general formula (1) is introduced into at least one of the surface and the inside of the silica film, a water-resistant aluminum pigment dispersion excellent in water dispersibility and storage stability is obtained. Further, when a tertiary amine is introduced into at least one of the surface and the inside of the silica film, a water-resistant aluminum pigment dispersion having particularly excellent water dispersibility and storage stability is obtained.

  As described above, the aluminum pigment before the formation of the silica film is a tabular grain having an average thickness of 5 nm to 30 nm and a 50% average particle diameter (R50) of 0.5 μm to 3 μm. It is preferable that With such tabular grains, an image having excellent metallic gloss can be recorded on a recording medium.

  The thickness of the silica film is preferably 0.5 nm or more and 10 nm or less, and more preferably 1 nm or more and 9 nm or less. If the thickness of the silica film is within the above range, particularly the lower limit value or more, water resistance can be imparted to the aluminum pigment. If the thickness is equal to or less than the upper limit value, the metal gloss is not deteriorated and water resistance is imparted. can do.

Determination of whether or not the compound represented by the general formula (1) is introduced into at least one of the surface and the inside of the silica film formed on the surface of the aluminum pigment is performed by, for example, X-ray photoelectron spectroscopy (hereinafter referred to as “X-ray photoelectron spectroscopy”). It can also be judged by means such as elemental analysis by XPS), identification of a compound by ¹ H-NMR spectrum, ¹³ C-NMR spectrum, ³¹ P-NMR spectrum, or the like.

  XPS is a spectroscopic method that measures the energy of photoelectrons emitted from a sample by X-ray irradiation. Since photoelectrons collide with molecules and are scattered immediately in the atmosphere, it is necessary to keep the apparatus in a vacuum. Also, photoelectrons emitted deep inside the solid sample are scattered within the sample and cannot escape from the surface. Therefore, XPS is effective as a surface analysis method because it measures photoelectrons only from the sample surface. In XPS, a range within a few nm from the sample surface can be analyzed.

3. Water-Resistant Aluminum Pigment The water-resistant aluminum pigment according to the present embodiment is obtained by the above-described production method and has the following characteristics.

（式（１）中、ＡＯはオキシアルキレン基を表し、Ｒは置換基を有してもよい炭素数５〜３０の炭化水素基を表し、ｎは５〜３５の整数を表す。） That is, the water-resistant aluminum pigment according to the present embodiment is a water-resistant aluminum pigment in which the surface of the aluminum pigment is coated with a silica film, and at least a part of the surface and the inside of the silica film has the following general formula ( The compound represented by 1) is introduced.

(In Formula (1), AO represents an oxyalkylene group, R represents a C5-C30 hydrocarbon group which may have a substituent, and n represents an integer of 5-35.)

  According to the water-resistant aluminum pigment according to the present embodiment, water resistance is imparted by forming a silica film on the surface of the aluminum pigment, so whitening when blended in an aqueous paint or an aqueous ink composition And has an excellent metallic luster. In addition, since the compound represented by the general formula (1) is introduced into at least one of the surface and the inside of the silica film, the water resistant aluminum pigment is excellent in water dispersibility and storage stability. Furthermore, when a tertiary amine is introduced into at least one of the surface and the inside of the silica film, the water resistant aluminum pigment is particularly excellent in water dispersibility and storage stability. Therefore, when the water-based ink composition using the water-resistant aluminum pigment according to the present embodiment is applied to an inkjet printer, nozzle clogging due to aggregation of the water-resistant aluminum pigments is suppressed, so that ink ejection Stability is improved.

  The shape of the raw material aluminum pigment, the thickness of the silica film, the analyzing means, and the like are the same as those described for the water-resistant aluminum pigment dispersion described above, and will be omitted.

4). Water-based ink composition The water-based ink composition according to the present embodiment is characterized by containing the aforementioned water-resistant aluminum pigment. Since the water-based ink composition according to the present embodiment contains the aforementioned water-resistant aluminum pigment having excellent water dispersibility, nozzle clogging caused by aggregation of the water-resistant aluminum pigments even when applied to an inkjet printer. Is suppressed. As a result, the ink ejection stability is improved. In the present invention, the “aqueous ink composition” means an ink composition containing 50% by mass or more, preferably 70% by mass or more of water as a solvent. It is preferable to use pure water or ultrapure water such as ion exchange water, ultrafiltered water, reverse osmosis water, or distilled water. In particular, water obtained by sterilizing these waters by ultraviolet irradiation or addition of hydrogen peroxide is preferable because generation of mold and bacteria can be suppressed over a long period of time.

  When the water-based ink composition contains a tertiary amine, the water-resistant aluminum pigment is particularly excellent in water dispersibility and storage stability. Therefore, when the water-based ink composition using the water-resistant aluminum pigment according to the present embodiment is applied to an inkjet printer, nozzle clogging due to aggregation of the water-resistant aluminum pigments is suppressed, so that ink ejection Stability is improved.

  The concentration of the water-resistant aluminum pigment in the aqueous ink composition according to the present embodiment is preferably 0.1 to 5.0% by mass, more preferably 0.1 to 3%, based on the total mass of the aqueous ink composition. 0.0 mass%, more preferably 0.25 to 2.5 mass%, particularly preferably 0.5 to 2.0 mass%.

  Resin, surfactant, alkanediol, polyhydric alcohol, pH adjuster, etc. can be added to the water-based ink composition according to the present embodiment.

  The resins have a function of firmly fixing the water-resistant aluminum pigment on the recording medium. Examples of the resins include acrylic acid, acrylic acid ester, methacrylic acid, methacrylic acid ester, acrylonitrile, cyanoacrylate, acrylamide, olefin, styrene, vinyl acetate, vinyl chloride, vinyl alcohol, vinyl ether, vinyl pyrrolidone, vinyl pyridine, vinyl Examples thereof include carbazole, vinylimidazole, vinylidene chloride homopolymer or copolymer, urethane resin, fluororesin, and natural resin. In addition, said copolymer can be used with any form of a random copolymer, a block copolymer, an alternating copolymer, and a graft copolymer.

  As the surfactant, it is preferable to contain an acetylene glycol surfactant or a polysiloxane surfactant. The acetylene glycol surfactant and the polysiloxane surfactant can improve the wettability of the recording surface of the recording medium or the like to increase the ink permeability. Examples of the acetylene glycol surfactant include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 3, Examples include 5-dimethyl-1-hexyn-3-ol, 2,4-dimethyl-5-hexyn-3-ol, and the like. Moreover, a commercial item can also be utilized for acetylene glycol-type surfactant, for example, Olphine E1010, STG, Y (above, Nissin Chemical Industry Co., Ltd. product), Surfynol 104, 82, 465, 485, TG (The above is manufactured by Air Products and Chemicals Inc.). Commercially available products can be used as the polysiloxane surfactant, and examples thereof include BYK-347, BYK-348 (above, manufactured by Big Chemie Japan Co., Ltd.) and the like. Further, the aqueous ink composition may contain other surfactants such as an anionic surfactant, a nonionic surfactant, and an amphoteric surfactant.

  Alkanediol can enhance the wettability of a recording surface such as a recording medium and improve the ink permeability. Examples of the alkanediol include 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, 1,2-octanediol, etc. , 2-alkanediol is preferred. Among these, 1,2-hexanediol, 1,2-heptanediol, and 1,2-octanediol having 6 to 8 carbon atoms are more preferable because of their particularly high permeability to recording media.

  For example, when the aqueous ink composition is applied to an inkjet recording apparatus, the polyhydric alcohol can suppress drying of the aqueous ink composition and prevent clogging of the aqueous ink composition in the inkjet recording head portion. Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, propylene glycol, butylene glycol, 1,2,6-hexanetriol, thioglycol, hexylene glycol, glycerin, and trimethylolethane. And trimethylolpropane.

  Examples of the pH adjuster include potassium dihydrogen phosphate, disodium hydrogen phosphate, sodium hydroxide, lithium hydroxide, potassium hydroxide, ammonia, diethanolamine, triethanolamine, triisopropanolamine, potassium carbonate, sodium carbonate, Examples thereof include sodium hydrogen carbonate.

  In addition, the water-based ink composition according to the present embodiment includes a fixing agent such as a water-soluble rosin, an antifungal agent / preservative such as sodium benzoate, an antioxidant / ultraviolet absorber such as an allophanate, a chelating agent, and an oxygen absorbing agent. An additive such as an agent can be contained. These additives can be used alone or in combination of two or more.

  The use of the water-based ink composition according to the present embodiment is not particularly limited, and can be applied to, for example, a writing instrument, a stamp, a recorder, a pen plotter, and an ink jet recording apparatus.

  The viscosity at 20 ° C. of the aqueous ink composition according to the present embodiment is preferably 2 mPa · s or more and 10 mPa · s or less, and more preferably 3 mPa · s or more and 5 mPa · s or less. When the viscosity of the aqueous ink composition at 20 ° C. is within the above range, an appropriate amount of the aqueous ink composition is ejected from the nozzle, and the flight bending and scattering of the aqueous ink composition can be further reduced. It can be preferably used.

5. Example 5.1. Example 1
5.1.1. Step (a)
Resin comprising cellulose acetate butyrate (butylation rate 35 to 39%, manufactured by Kanto Chemical Co., Ltd.) 3.0 mass% and diethylene glycol diethyl ether (produced by Nippon Emulsifier Co., Ltd.) 97 mass% on a PET film having a thickness of 100 μm The layer coating solution was uniformly applied by a bar coating method and dried at 60 ° C. for 10 minutes to form a resin layer thin film on the PET film. Subsequently, an aluminum vapor deposition layer having an average film thickness of 20 nm was formed on the resin layer using a vacuum vapor deposition device (“VE-1010 type vacuum vapor deposition device”, manufactured by Vacuum Device Co., Ltd.). Next, the laminate formed by the above method is subjected to peeling, miniaturization, and dispersion treatment simultaneously in diethylene glycol diethyl ether using a VS-150 ultrasonic disperser (manufactured by ASONE Co., Ltd.), and integrated ultrasonic dispersion An aluminum pigment dispersion having a treatment time of 12 hours was prepared. The obtained aluminum pigment dispersion was filtered through 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. Thereby, the aluminum pigment dispersion was concentrated, and then the concentration of the aluminum pigment dispersion was adjusted to obtain a 5.0 mass% aluminum pigment dispersion.

5.1.2. Step (b)
Next, 100 parts by mass of the obtained aluminum pigment dispersion was put into a beaker, to which was added 10.4 parts by mass of tetraethoxysilane (TEOS) and 2 parts by mass of 1 mol / L aqueous ammonia as a basic catalyst, Hydrolysis condensation was performed by stirring at room temperature for 7 days. As a result, an aluminum pigment dispersion containing an aluminum pigment having a silica film formed on the surface thereof was obtained.

5.1.3. Step (c)
Next, it was centrifuged (10,000 rpm, 60 minutes) to remove diethylene glycol diethyl ether contained in the aluminum pigment dispersion which was the supernatant. In this way, the aluminum pigment having a silica film formed on the surface was separated.

5.1.4. Step (d)
Using 1 mol of ricinoleic acid as a starting material, polycondensation with 1 mol equivalent of polyethylene glycol 1000 (average molecular weight 1000) was performed in the presence of 0.1 mol of sulfuric acid as an acid catalyst. The reaction is carried out in an Ar gas atmosphere at 70 ° C. for 48 hours, and the product is purified using high performance liquid chromatography (LC-20AP, manufactured by Shimadzu Corporation), whereby the compound A represented by the following general formula (3) is obtained. Obtained. The compound was identified by NMR (JNM-ECS400, manufactured by JEOL Ltd.), FT-IR (FTS7000, manufactured by Digilab), ESI-MS (Q-Tof, manufactured by Micromass), and the following general formula (3) It was found to be a mixture having a molecular weight distribution containing a compound in which n is 8 to 19.

  Next, 94.9 parts by mass of ion-exchanged water is put into a beaker, and 0.1 parts by mass of the compound represented by the above general formula (3) is added to the beaker. An aqueous solution in which the compound represented by is completely dissolved was obtained. The aqueous solution thus obtained was added to 5 parts by mass of the aluminum pigment having a silica film formed on the surface obtained in step (c) to make the total amount 100 parts by mass, and further at room temperature for 1 day. Stir. In this way, a water resistant aluminum pigment dispersion according to Example 1 was obtained.

5.2. Examples 2-9, Comparative Examples 1-6
In the step (d) of Example 1 above, each of the Examples 2 to 9 and Comparative Examples 1 to 6 was performed in the same manner as in Example 1 except that the aqueous solutions having the components and addition amounts shown in Table 1 were used. A water-resistant aluminum pigment dispersion was obtained. In addition, each component in Table 1 is as follows.

・ "Compound B"
Using 1 mol of linoleic acid as a starting material, polycondensation with 1 mol equivalent of polyethylene glycol 1000 (average molecular weight 1000) was carried out in the presence of 0.1 mol of sulfuric acid as an acid catalyst. The reaction is carried out in an Ar gas atmosphere at 70 ° C. for 48 hours, and the product is purified using high performance liquid chromatography (LC-20AP, manufactured by Shimadzu Corporation) to obtain a compound B represented by the following general formula (4). Obtained. When the compound was identified by NMR (JNM-ECS400 manufactured by JEOL Ltd.), FT-IR (FTS7000 manufactured by Digilab), ESI-MS (Q-Tof manufactured by Micromass), the following general formula (4) It was found to be a mixture having a molecular weight distribution containing a compound in which n is 8 to 19.

・ "TEA" (manufactured by Kanto Chemical Co., Inc., triethanolamine)
・ "TPA" (Kanto Chemical Co., Ltd., tripropanolamine)
・ "PEG400" (trade name "PEG # 400", manufactured by Lion Corporation, polyethylene glycol)
"E1010" (trade name "Olfin E1010", manufactured by Nissin Chemical Industry Co., Ltd., acetylenediol ethylene oxide (10 mol) addition product)
・ EDTA (manufactured by Tokyo Chemical Industry Co., Ltd., ethylenediaminetetraacetic acid)
・ "TEGmBE" (manufactured by Kanto Chemical Co., Ltd., triethylene glycol monobutyl ether)
・ "1,2-HD" (Kanto Chemical Co., Inc., 1,2-hexanediol)

5.3. Evaluation test 5.3.1. Water dispersibility evaluation test The water dispersibility was evaluated according to how much the water-resistant aluminum pigment dispersion obtained above passed through a 10 μm filter (MITIP MEMBRANE FILTERS (model number: LCWPO4700) manufactured by MILIPORE). did. Evaluation criteria for water dispersibility are as follows. The results of the water dispersibility evaluation test are also shown in Table 1.
"A" ... Filter passage amount is 50mL or more "B" ... Filter passage amount is 30mL or more and less than 50mL "C" ... Filter passage amount is 10mL or more but less than 30mL "D" ... Filter passage is less than 10mL

5.3.2. Storage Stability Evaluation Test 10 mL of the water resistant aluminum pigment dispersion obtained above was added to a sample bottle, sealed, and allowed to stand at a constant temperature of 25 ° C. The storage stability of the water-resistant aluminum pigment dispersion was evaluated by visually observing the change with time. The evaluation criteria for storage stability are as follows. The results of the water resistance evaluation test are also shown in Table 1.
“A” —no whitening and separation after 100 days “B” —no whitening and separation after 30 days “C” —whitening or separation in less than 30 days

5.3.3. Glossiness Evaluation One of the water-resistant aluminum pigment dispersions obtained above is dropped and applied to photographic paper ("PM photographic paper (glossy) model number: KA450PSK", manufactured by Seiko Epson Corporation) at room temperature. And dried for 1 day. The gloss of the water-resistant aluminum pigment was evaluated by observing the obtained sample visually and with a scanning electron microscope (S-4700, manufactured by Hitachi High-Technologies Corporation, hereinafter also referred to as “SEM”). The evaluation criteria for the glossiness of the water-resistant aluminum pigment are as follows. The results of the gloss evaluation test are also shown in Table 1.
“A”: Good gloss (excellent metal gloss and specular gloss)
“B” —Slightly good gloss (excellent metal gloss but slightly matte)
“C”: poor gloss (not metallic gloss, blackish gray)

5.3.4. Evaluation Results Table 1 shows the results of evaluation tests of water dispersibility, storage stability, and glossiness of the water resistant aluminum pigment dispersions obtained in Examples 1 to 9 and Comparative Examples 1 to 6. The unit of numerical values in Table 1 is “parts by mass”.

  According to the results in Table 1, the water resistant aluminum pigments of Examples 1 to 9 dispersed in an aqueous solution containing the compound represented by the general formula (1) are represented by the general formula (1). As compared with the water-resistant aluminum pigments of Comparative Examples 1 to 6 dispersed in an aqueous solution containing no compound, it was found that the water dispersibility and storage stability were good and the gloss of the recorded matter was also excellent.

  Moreover, according to the result of Table 1, the water resistant aluminum pigment dispersed in the aqueous solution containing the compound represented by the general formula (1) and the tertiary amine is represented by the general formula (1). It has been found that the water dispersibility and storage stability are particularly good compared to water resistant aluminum pigments dispersed in an aqueous solution containing a compound with no tertiary amine.

5.4. Evaluation of water-based ink composition 5.4.1. Preparation of aqueous ink composition Water-resistant aluminum pigment dispersion, glycerin, trimethylolpropane, 1,2-hexanediol, orphine E1010, and triethanolamine are mixed so that the following composition is obtained, and further becomes 100 parts by mass. As such, ion-exchanged water was added and mixed and stirred.

<Composition of water-based ink composition>
Water-resistant aluminum pigment dispersion (solid content) 1 part by weight Glycerin 10 parts by weight Trimethylolpropane 5 parts by weight 1,2-hexanediol 1 part by weight Orphine E1010 1 part by weight Triethanolamine 1 part by weight Ion-exchanged water Remainder Total 100 parts by weight Part

  As the water resistant aluminum pigment dispersion, any one of the water resistant aluminum pigment dispersions obtained in Example 2, Example 5, and Comparative Example 1 obtained above was used.

5.4.2. Preparation of Evaluation Sample An ink cartridge in which the above-described aqueous ink composition was filled in a dedicated cartridge of an inkjet printer PX-G930 (manufactured by Seiko Epson Corporation) was prepared. Next, the obtained ink cartridge was attached to the black row of the inkjet printer PX-G930, and commercially available ink cartridges were attached to the other nozzle rows. A commercially available ink cartridge mounted in a place other than the black row is used as a dummy and is not used in the evaluation of this embodiment, and thus does not contribute to the effects of the present invention.

  Next, the above-described aqueous ink composition mounted in a black row is ejected onto photographic paper <glossy> (manufactured by Seiko Epson Corporation) using the above-described printer, thereby recording a solid pattern image printed thereon. I got a thing. The printing conditions were such that the weight of ink ejected per dot was 20 ng, and the resolution was 720 dpi vertically and 720 dpi horizontally.

5.4.3. Image Evaluation Method The obtained image was measured for glossiness at 60 ° using a gloss meter MULTI Gloss 268 (manufactured by Konica Minolta). The evaluation criteria for the glossiness of the obtained image are as follows. Table 2 shows the results of the glossiness evaluation test.
"A": Glossiness of 300 or more (clear metallic luster)
“B”: glossiness of 250 to less than 300 (matte metallic luster)
"C": Glossiness of 200 or more and less than 250 (no metallic luster)
“D”: measurement not possible (water-based ink composition could not be ejected)

  As shown in Table 2, the water-based ink compositions prepared using the water-resistant aluminum pigment dispersions of Examples 2 and 5 have a glossiness of 300 or more, and print an image having a clear metallic gloss. I was able to.

  On the other hand, the water-based ink composition produced using the water-resistant aluminum pigment dispersion liquid of Comparative Example 1 could not eject ink from the head of the ink jet recording apparatus and could not record an image. This is considered to be due to clogging of the head portion due to aggregation of the water resistant aluminum pigment in the water-based ink composition and increase in the particle size.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the present invention includes substantially the same configuration (for example, a configuration having the same function, method, and result, or a configuration having the same purpose and effect) as the configuration described in the embodiment. In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

Claims (7)

0.25 to 2.5% by mass of a water-resistant aluminum pigment whose surface is coated with a silica film,
A compound represented by the following general formula (1) , and
50% by weight or more of water
An ink composition for an inkjet printer, comprising:

(In Formula (1), AO represents an oxyalkylene group, R represents a C5-C30 hydrocarbon group which may have a substituent, and n represents an integer of 5-35.) The ink composition for an ink jet printer according to claim 1, wherein, in the general formula (1), the R further has an unsaturated bond. The content ratio of the compound represented by the general formula (1) is 0.05 parts by mass or more and 2.5 parts by mass or less with respect to 1 part by mass of the water-resistant aluminum pigment. The ink composition for inkjet printers of description. Furthermore, the ink composition for inkjet printers as described in any one of Claim 1 thru | or 3 containing a tertiary amine. The ink composition for an inkjet printer according to claim 4, wherein a content ratio of the tertiary amine is 0.05 parts by mass or more and 2.5 parts by mass or less with respect to 1 part by mass of the water-resistant aluminum pigment. The aluminum pigment has an average thickness of 5 nm to 30 nm and 0.5 μm
The ink composition for an ink jet printer according to any one of claims 1 to 5, wherein the ink composition is a tabular grain having a 50% average particle diameter of m to 3 µm. The ink composition for an ink jet printer according to any one of claims 1 to 6, wherein a viscosity at 20 ° C is 2 mPa · s or more and 10 mPa · s or less.