JP6890957B2 - Ink composition manufacturing method - Google Patents

Description

The present invention relates to a process for the preparation of an ink composition containing a metallic Pigments.

In recent years, inks capable of forming images having metallic luster, so-called metallic inks, have been developed. As the pigment (metallic pigment) used for metallic ink, an aluminum pigment is often used. Further, from the viewpoint of environmental consideration and worker safety, it is desired to develop a water-based ink composition capable of reducing the amount of organic solvent emitted.

However, when the aluminum pigment is dispersed in water, it has a problem that it becomes whitened or transparent by forming an oxide by the reaction with water, and the metallic luster is impaired.

Patent Document 1 describes a water-resistant aluminum pigment dispersion having improved water resistance of an aluminum pigment in order to suppress whitening and transparency.

JP-A-2010-202815

Patent Document 1 describes that the water resistance of an aluminum pigment is improved by performing a step of producing an aluminum pigment by crushing or the like in an organic solvent containing a phosphoric acid ester-type surfactant. However, the method of Patent Document 1 is insufficient to suppress whitening and transparency, and is still a problem.

Therefore, in view of the above-mentioned problems, it is an object of the present invention to provide a method for producing an ink composition containing a metallic pigment having sufficiently improved water resistance.

One aspect of the present invention is a method for producing an ink composition, in which a first step of preparing particles containing metallic aluminum or an aluminum alloy and a liquid containing condensed aluminum phosphate are brought into contact with the particles. by, characterized a second step of obtaining a metallic pigment forming a coating containing a condensed aluminum phosphate on the surface of the particles, said metallic pigment, and a third step of mixing the water, and that it has And.

According to the present invention, it is possible to provide a method for producing an ink composition containing a metallic pigment having sufficiently improved water resistance.

Hereinafter, embodiments of the present invention will be described in detail. The present invention is not limited to the following embodiments, and is appropriately modified with respect to the following embodiments based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention. Those with improvements and the like are also included in the scope of the present invention.

[Metallic pigment]
The metallic pigment according to the present embodiment contains particles containing metallic aluminum or an aluminum alloy (hereinafter referred to as "aluminum-containing particles"), and the surface of the particles contains aluminum phosphate or condensed aluminum phosphate. As used herein, the metallic pigment is a pigment capable of forming a coating film having a metallic luster when a coating film is formed using a dispersion liquid in which the metallic pigment is dispersed in a liquid.

(Aluminum-containing particles)
The aluminum-containing particles are particles containing metallic aluminum or an aluminum alloy, and are preferably particles containing metallic aluminum. The aluminum alloy is an alloy containing aluminum as a main component, and contains metal elements such as Fe, Cu, Mn, Mg, Cr, Zn, Ti, V, Bi, Pb, Zr, and Si, and non-metal elements. The aluminum alloy in the present embodiment is not particularly limited as long as it is an alloy in which the aluminum-containing particles exhibit metallic luster. Further, the "metal aluminum or aluminum alloy" in the present embodiment may be a generally used pure aluminum or aluminum alloy such as A1000 series to A8000 series defined by Japanese Industrial Standards (JIS H4000). preferable.

The metallic pigment according to the present embodiment contains aluminum phosphate or condensed aluminum phosphate on the surface of aluminum-containing particles. By containing aluminum phosphate on the surface of the aluminum-containing particles, it is possible to prevent the aluminum-containing particles from reacting with water to whiten or become transparent, and to realize a metallic pigment with improved water resistance. Can be done.

The present inventors speculate the mechanism by which the water resistance can be improved by containing aluminum phosphate or condensed aluminum phosphate on the surface of the aluminum-containing particles as follows. When aluminum phosphate is contained on the surface of aluminum-containing particles, the particle surface of the aluminum-containing particles is protected by aluminum phosphate. As a result, the reaction between aluminum and water contained in the aluminum-containing particles on the particle surface is suppressed, and the formation of hydroxides or oxides due to the reaction between aluminum and water is less likely to occur. Therefore, it is considered that the water resistance of the aluminum-containing particles can be improved by containing aluminum phosphate on the surface of the aluminum-containing particles.

It is considered that the water resistance can be improved by using a phosphoric acid ester type surfactant as in Patent Document 1, but the effect of improving the water resistance is insufficient for the following reasons. It is believed that there is. Phosphate ester-type surfactants have bulky hydrocarbon groups (eg, alkyl groups). When aluminum-containing particles are surface-treated with a phosphoric acid ester-type surfactant, bulky hydrocarbon groups repel each other three-dimensionally, so that a sufficient amount of phosphoric acid ester-type surfactant is contained in the particles of the aluminum-containing particles. It is considered that it becomes difficult to adsorb to the surface. Further, it is considered that the phosphate ester-type surfactants are unlikely to form a bond on the surface of the aluminum-containing particles, and it is presumed that the adsorption layer is formed in the form of a monolayer, and the thickness of the adsorption layer is not sufficient. Conceivable. Therefore, it is considered that the water resistance of the aluminum-containing particles cannot be sufficiently improved by the surface treatment using the phosphoric acid ester type surfactant.

On the other hand, as will be described later, in the present embodiment, a liquid and aluminum containing at least one selected from the group consisting of phosphoric acid, polyphosphoric acid, phosphoric acid amine salt, polyphosphoric acid amine salt, and metal phosphate metal salt. Surface treatment is performed by contacting the contained particles. According to this surface treatment, aluminum phosphate can be contained on the surface of the aluminum-containing particles. According to this embodiment, since the above-mentioned phosphoric acid-based compound does not have a bulky group such as an alkyl group, it is considered that there is little steric repulsion between the phosphoric acid-based compounds in the vicinity of the particle surface of the aluminum-containing particles. Therefore, it is considered that a sufficient amount of the phosphoric acid compound is adsorbed on the particle surface of the aluminum-containing particles. Further, it is considered that the phosphoric acid compounds undergo a condensation reaction between the phosphoric acid groups on the surface of the aluminum-containing particles to form a three-dimensional network of the phosphoric acid compounds. As a result, according to the present embodiment, it is considered that a dense layer or film containing a condensate of a phosphoric acid-based compound can be formed on the particle surface of the aluminum-containing particles. As a result, it is considered that the water resistance of the aluminum-containing particles can be sufficiently improved. These coatings have a thickness that does not impair the metallic luster.

The aluminum-containing particles may have a film made of an inorganic material such as aluminum oxide or silica on the surface thereof. That is, the aluminum-containing particles may be a core-shell type pigment having a core made of metallic aluminum or an aluminum alloy and a shell covering at least a part of the surface of the core. The shell then contains at least one selected from the group consisting of aluminum oxide and silica. Water resistance can be improved by providing a film made of an inorganic material on the surface of the aluminum-containing particles in this way. In this case as well, water resistance can be further improved by containing aluminum phosphate on the surface of the aluminum-containing particles. Can be improved.

The metallic pigment preferably has a film containing aluminum phosphate on the surface of the aluminum-containing particles. By covering the aluminum-containing particles with a film containing aluminum phosphate, the water resistance can be further improved. When the aluminum-containing particles are the core-shell type pigment as described above, the shell may form a film containing aluminum phosphate by containing aluminum phosphate, or the shell may form a film containing aluminum phosphate. It may have a film containing aluminum phosphate on the outside. Further, the shell may contain aluminum phosphate, and the portion of the surface of the core not covered by the shell may contain aluminum phosphate to form a film containing aluminum phosphate.

(Shape of metallic pigment)
The shape of the metallic pigment is not particularly limited, but various shapes such as granular, plate-like, lump-like, and flake-like (scale-like) can be used. Among these, a plate-like or flake-like shape is preferable from the viewpoint of giving an excellent metallic luster to the coating film.

The average particle size of the metallic pigment is not particularly limited, but is preferably 0.5 μm or more, and more preferably 1 μm or more. The average particle size of the metallic pigment is preferably 100 μm or less, more preferably 50 μm or less, and particularly preferably 5 μm or less.

By setting the average particle size of the metallic pigment to 0.5 μm or more, it is possible to facilitate handling in the manufacturing process, and the metallic pigment tends to be less likely to aggregate. Further, by setting the average particle size of the metallic pigment to 100 μm or less, it is possible to prevent the surface of the coating film from being roughened when used as an ink. Further, by setting the average particle size of the metallic pigment to 5 μm or less, the ejection stability can be improved when the metallic pigment is used as an ink jet ink. The average particle size of the metallic pigment can be obtained by calculating the volume average based on the volume-based particle size distribution obtained by measuring by the light scattering type particle size distribution measuring method.

(Other additive ingredients)
The metallic pigment may have a coloring pigment in addition to the aluminum-containing particles. When the metallic pigment has a coloring pigment, it is preferable that the coloring pigment adheres to the surface of the aluminum-containing particles. The expression "the coloring pigment adheres to the surface of the aluminum-containing particles" in the present specification is not limited to the form in which the coloring pigment directly adheres to the surface of the aluminum-containing particles. That is, the form in which the coloring pigment is attached to the film formed on the surface of the aluminum-containing particles or the attached material is also included. As the coloring pigment, a pigment having a conventionally known chromatic color-imparting effect or a pigment having a black or white color-imparting effect can be used. When the metallic pigment has a colored pigment, the metallic pigment can be a colored metallic pigment.

[Manufacturing method of metallic pigment]
The method for producing a metallic pigment according to this embodiment is
[1] The first step of preparing a powder containing aluminum-containing particles, and
[2] A solution containing at least one selected from the group consisting of phosphoric acid, polyphosphoric acid, phosphoric acid amine salt, polyphosphoric acid amine salt, primary metal phosphate salt, and secondary metal phosphate salt, and the above. The second step of contacting the powder and
Have.

Hereinafter, each step will be described.

<First step>
In this step, a powder containing aluminum-containing particles is prepared. The shape of the aluminum pigment particles is not particularly limited, and may be any of granular, plate-like, lump-like, and flake-like (scale-like) shapes. As described above, the shape of the metallic pigment is preferably plate-shaped or flake-shaped from the viewpoint of giving an excellent metallic luster to the coating film. Therefore, the shape of the aluminum-containing particles prepared in this step is also plate-shaped or flake-shaped. Is preferable.

The method for preparing the aluminum powder is not particularly limited, and examples thereof include the following methods.

As a first method, there is a method of forming a powder containing granular aluminum-containing particles by an atomizing method.

As a second method, a method of crushing a powder containing granular aluminum-containing particles with a ball mill or the like to form a powder containing plate-shaped or flake-shaped aluminum-containing particles can be mentioned.

As a third method, there is a method of forming a powder containing aluminum-containing particles in the form of plates or flakes by forming an aluminum film on a substrate and then peeling and crushing the aluminum film. As a method for forming an aluminum film on a substrate, it is preferable to apply a vacuum deposition, ion plating or sputtering method.

The powder containing granular aluminum-containing particles in the second method and the aluminum film in the third method can be regarded as an aluminum-containing raw material. Therefore, these methods are methods of forming a powder containing aluminum-containing particles in the form of plates or flakes by crushing the aluminum-containing raw material.

Further, as a fourth method, there is a method of using a commercially available powder containing aluminum-containing particles (for example, aluminum leaf powder manufactured by Oike Imaging Co., Ltd.).

<Second step>
In this step, the powder containing the aluminum-containing particles prepared in the first step is brought into contact with the solution containing the following phosphoric acid-based compound. As a result, a metallic pigment containing aluminum phosphate is produced on the surface of the aluminum-containing particles.

(Solution containing phosphoric acid compound)
The phosphoric acid-based compound according to the present embodiment is at least one selected from the group consisting of phosphoric acid, polyphosphoric acid, phosphoric acid amine salt, polyphosphoric acid amine salt, and phosphoric acid metal salt. These phosphoric acid compounds can be used alone or in combination of two or more of them. As the metal phosphate, it is preferable to use a first metal phosphate or a second metal phosphate. Specific examples of the primary metal phosphate salt include primary aluminum phosphate, primary calcium phosphate, primary zinc phosphate, and primary titanium phosphate. Specific examples of the amine phosphate include primary ammonium phosphate, ammonium secondary phosphate, ammonium tertiary phosphate, methylamine primary phosphate, methylamine secondary phosphate, methylamine tertiary phosphate, and first. Ethylamine phosphate, ethylamine diphosphate, ethylamine tertiary phosphate, alkanolamine primary phosphate, alkanolamine diphosphate, alkanolamine tertiary phosphate can be mentioned. Specific examples of the metal phosphate salt include primary magnesium phosphate, secondary magnesium phosphate, primary calcium phosphate, secondary calcium phosphate, primary zinc phosphate, zinc secondary phosphate, barium primary phosphate, and secondary phosphate. Barium Phosphate, Aluminum Primary Phosphate, Aluminum Distillate Phosphate, Gallium Diary Phosphate, Gallium Di ratherate, Lantern Primary Phosphate, Lantern Secondary Phosphate, Titanium Primary Phosphate, Secondary Phosphate Examples thereof include titanium, primary zirconium phosphate, and secondary zirconium phosphate.

Among these, as the phosphoric acid compound according to the present embodiment, the first phosphorus San'a aluminum are preferred. By using the first phosphorus San'a aluminum as phosphate compound, it is possible to produce a metallic pigment on the surface of the aluminum-containing particles containing aluminum phosphate efficiently.

The liquid containing the phosphoric acid-based compound according to the present embodiment is not particularly limited as long as it contains the above-mentioned phosphoric acid-based compound. The solvent of the liquid may be water or an organic solvent such as alcohol. The liquid containing the phosphoric acid-based compound is preferably an aqueous solution of the above-mentioned phosphoric acid-based compound.

The content of the phosphoric acid-based compound in the liquid containing the phosphoric acid-based compound is preferably 0.01% by mass or more and 20% by mass or less when the total amount of the liquid is 100% by mass. More preferably, it is 05% by mass or more and 15% by mass or less. By setting the content of the phosphoric acid compound in the liquid to 0.01% by mass or more, aluminum phosphate can be efficiently produced on the surface of the aluminum-containing particles, and the water resistance of the obtained metallic pigment is improved. Can be made to. Further, by setting the content of the phosphoric acid compound to 20% by mass or less, it is possible to suppress the decrease in metallic luster of the metallic pigment.

(Contact method)
The method of contacting the powder containing the aluminum-containing particles with the liquid containing the phosphoric acid-based compound is not particularly limited. There is a method in which a powder containing aluminum-containing particles is added to a liquid containing a phosphoric acid-based compound and mixed. At this time, the aluminum-containing particles may be dispersed in the liquid, and this liquid and the liquid containing a phosphoric acid-based compound may be mixed.

When the first step is a step of forming a powder containing aluminum-containing particles in the form of plates or flakes by crushing the aluminum-containing raw material, the first step is carried out in a liquid containing a phosphoric acid-based compound. You may go. Thereby, the powder containing the aluminum-containing particles in the form of plates or flakes to be produced can be brought into contact with the liquid containing the phosphoric acid-based compound.

The liquid or the aluminum-containing particles may be heated before or during the contact between the powder containing the aluminum-containing particles and the liquid containing the phosphoric acid-based compound. Alternatively, the aluminum-containing particles may be heated after the powder containing the aluminum-containing particles and the liquid containing the phosphoric acid-based compound are brought into contact with each other. Thereby, the reaction of the phosphoric acid-based compound on the surface of the aluminum-containing particles can be promoted, and the phosphoric acid-based compound can be bound or adsorbed on the surface of the aluminum-containing particles. In addition, heating can promote dehydration condensation between the phosphoric acid groups of a plurality of phosphoric acid compounds. Thereby, the formation of aluminum phosphate on the surface of the aluminum-containing particles can be promoted. At this time, it is considered that the constituent components other than aluminum phosphate on the surface of the aluminum-containing particles are metallic aluminum, aluminum alloy, aluminum oxide, aluminum hydroxide, or a composite thereof.

If more phosphoric acid-based compounds are attached to the surface of the aluminum-containing particles, a process of washing and removing them may be carried out using a liquid such as water or alcohol.

[Ink composition, manufacturing method of ink composition]
The ink composition according to this embodiment contains the above-mentioned metallic pigment and water. Further, the method for producing an ink composition according to the present embodiment includes a step of mixing the above-mentioned metallic pigment and water.

The concentration of the aluminum pigment in the ink composition according to the present embodiment is preferably 0.1% by mass or more and 5.0% by mass or less when the total mass of the ink composition is 100% by mass. Further, it is more preferably 0.25% by mass or more and 3.0% by mass or less, and particularly preferably 0.5% by mass or more and 2.0% by mass or less.

The ink composition according to this embodiment contains water. The content of water in the ink composition is preferably 50% by mass or more and 90% by mass or less when the total mass of the ink composition is 100% by mass. Further, it is more preferably 60% by mass or more and 90% by mass or less, and particularly preferably 70% by mass or more and 85% by mass or less.

As the water, it is preferable to use ion-exchanged water, ultrafiltration water, reverse osmosis water, ultrapure water, or the like. In addition to water, an organic solvent may be used in combination as the solvent. Examples of such an organic solvent include alcohols such as ethanol, methanol, butanol, and propanol.

A surfactant, a polyhydric alcohol, or the like can be added to the ink composition according to the present embodiment, if necessary.

The surfactant added to the ink composition according to the present embodiment may be any of an anionic surfactant, a nonionic surfactant, and an amphoteric surfactant. Suitable surfactants contained in the ink composition according to the present embodiment include, for example, acetylene glycol-based surfactants such as polyoxyacetylene glycol. Examples of the acetylene glycol-based surfactant include polyoxyethylene acetylene glycol such as POE (10) acetylene glycol. As the acetylene glycol-based surfactant, a commercially available product can also be used, and examples thereof include acetylenol E100 (all manufactured by Kawaken Fine Chemical Co., Ltd.).

The content of the surfactant in the ink composition is preferably 0.01% by mass or more and 5% by mass or less, preferably 0.1% by mass or more, when the total mass of the ink composition is 100% by mass. It is more preferably 1% by mass or less.

In the ink composition according to the present embodiment, a polyhydric alcohol may be added in addition to the above components. The polyhydric alcohol can prevent the ink from drying and prevent the ink from clogging in the inkjet recording head portion.

Examples of the polyhydric alcohol include glycerin, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol and the like.

The content of the polyhydric alcohol is preferably 0.1% by mass or more and 20% by mass or less, and more preferably 0.5% by mass or more and 10% by mass or less, based on the total mass of the ink composition.

The ink composition according to the present embodiment can form a metallic image having a metallic luster by being applied to various recording media (base materials). That is, the ink composition according to this embodiment is a metallic ink composition. Examples of the recording medium include paper, polymer materials such as vinyl chloride and PET, metals, wood, fabrics, glass, and ceramics. The shape of the recording medium is not particularly limited, and may be a film, a plate, or another three-dimensional object.

The use of the ink composition according to the present embodiment is not particularly limited, but it can be applied to various inkjet recording methods. Examples of the inkjet recording method include a thermal jet type inkjet and a piezo type inkjet. It can also be applied to, for example, writing tools, stamps, and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the technical scope of the present invention is not limited to the following Examples.

(Example 1)
<Adjustment of ink composition>
First, an aluminum leaf powder solution (manufactured by Oike Imaging Co., Ltd.) was prepared. The aluminum leaf powder liquid is a liquid in which flaky particles containing metallic aluminum are dispersed in butyl acetate, and has a solid content concentration of 10.5% by mass. The average particle size of the flake-shaped aluminum particles is 1 to 20 μm, and the thickness is about 10 to 500 nm.

Next, a liquid containing the first aluminum phosphate, which is a phosphoric acid compound, was prepared. The above liquid was prepared by diluting an aluminum phosphate binder (Acidphos 75, manufactured by TAKI CHEMICAL CO., LTD.) 100 times (mass ratio) with ion-exchanged water. Here, Acidhos 75 is an aqueous solution of primary aluminum phosphate, and the concentration of primary aluminum phosphate in Acidhos 75 is 59% by mass. Therefore, the concentration of primary aluminum phosphate in the prepared liquid is 0.59% by mass.

5 g of the aluminum leaf powder liquid was mixed with 5 g of the liquid containing aluminum phosphate. As a result, the liquid containing aluminum phosphate, which is a phosphoric acid compound, and the particles containing metallic aluminum were brought into contact with each other.

Then, 10 g of ion-exchanged water, 5 g of 2-propanol, and 0.1 g of acetylenol were added to this mixed solution and mixed to prepare an ink composition.

<Water resistance evaluation of metallic pigments>
The ink composition according to Example 1 retained a metallic color (metallic luster) considered to be derived from metallic aluminum even after being allowed to stand at room temperature for 1 week after preparation.

The ink composition according to Example 1 was cast on a slide glass and dried to prepare an ink film on the slide glass. The ink film on the slide glass was immersed in warm water at 80 ° C. for 5 minutes, and it was evaluated whether or not the metallic color (metallic luster) changed. In Example 1, the metallic color (metallic luster) was maintained even after immersion.

(Comparative Example 1)
<Adjustment of ink composition>
An aluminum leaf powder solution (manufactured by Oike Imaging Co., Ltd.) was prepared in the same manner as in Example 1.

Then, 15 g of ion-exchanged water, 5 g of 2-propanol, and 0.1 g of acetylenol were added to 5 g of the aluminum leaf powder solution and mixed to prepare an ink composition.

<Water resistance evaluation of metallic pigments>
In the ink composition according to Comparative Example 1, the metallic aluminum metallic color (metallic luster) was lost after being allowed to stand at room temperature for several days after preparation, and a white solid was precipitated after being allowed to stand for one week. It is considered that this is because metallic aluminum reacts with water and is oxidized to amorphous aluminum oxide, which is whitened and / or made transparent.

Claims (4)

A method for producing an ink composition.
The first step of preparing particles containing metallic aluminum or an aluminum alloy, and
By contacting the liquid containing the condensed aluminum phosphate and the particles, the surfaces of the particles, a second step Ru obtain a metallic pigment forming a coating containing a condensed aluminum phosphate,
A method for producing an ink composition , which comprises a third step of mixing the metallic pigment and water. Method of manufacturing an ink composition according to claim 1 wherein the particles, which contain metallic aluminum. The method for producing an ink composition according to claim 1 or 2, wherein alcohols are further mixed in the third step. The method for producing an ink composition according to any one of claims 1 to 3, wherein a surfactant is further mixed in the third step.