KR100658411B1 - Method for manufacturing an aluminum flake pigment - Google Patents

Abstract

Aluminum flake pigments with excellent metallic luster, fine grains, and an appearance of a luxurious plating bath such as silver. The pigment is obtained by grinding an aluminum powder in an organic solvent, in the range of the 0.025㎛ 0.08㎛ to the average thickness (t), the mean particle size (D ₅₀₎ in the range of 8㎛ to 30㎛. It is preferable that the said aluminum powder is aluminum powder manufactured by the spraying method. Ball mills are preferred as such polishers.

Aluminum flake pigment, coating composition, ink composition, coating film

Description

Manufacturing method of aluminum flake pigment {METHOD FOR MANUFACTURING AN ALUMINUM FLAKE PIGMENT}

The present invention relates to a metallic flake pigment. More specifically, the present invention relates to an aluminum flake pigment that is excellent in metallic luster, fine grained, and has the appearance of an advanced plating bath such as silver.

Moreover, this invention relates to the metallic coating composition, metallic ink composition, and these coating films which are excellent in metal gloss, have a fine grain, and have the appearance of an advanced plating bath like silver.

Conventionally, aluminum flake pigments include bodies and parts thereof such as automobiles, motorcycles, bicycles and other vehicles, optical devices such as cameras and video cameras, OA equipment, sports products, food, beverages, cosmetics, containers, etc. In various fields, such as acoustic products such as cassette recorders, CD players, household goods such as vacuum cleaners, telephones, televisions, or in the fields of gravure printing, offset printing, screen printing, etc. luster) has been widely used as a pigment.

To date, various types of aluminum flake pigments have been developed in each aspect, but as representative examples thereof, as disclosed in Japanese Patent Application Laid-open No. Hei 10-1625, for example, an average particle diameter of 18 to 30 mu m is shown. Aluminum flake pigment etc. which exist in the range and whose average thickness is 0.5-1.5 micrometers are used.

However, the characteristics required for aluminum flake pigments in these fields are improving year by year, and especially in gravure printing, offset printing, screen printing, etc., the metallic luster is excellent, the texture is high, and the plating bath such as silver has a luster. There is a need for aluminum flake pigments that provide a high quality printed layer. On the other hand, also in the field of coating compositions, there is a strong demand for aluminum flake pigments capable of obtaining a high quality coating film having the luster of a plating bath.

In response to such a requirement, conventionally, by using aluminum deposition flake pigment obtained by depositing aluminum on a resin film with a thickness in the range of 0.02 to 0.06 탆, and then pulverizing the deposited aluminum thin film obtained by dissolving and removing the film. I've coped.

However, since this method has a very low productivity, performance and cost are not balanced, and its use is limited to a narrow use range. Further, even when thin aluminum flake pigments such as vapor deposition powder are prepared by wet grinding or grinding (hereinafter simply referred to as grinding) using a conventional ball mill or the like, grinding is performed before the thickness becomes sufficiently thin. Since it is segmented by, even if such aluminum flake pigment is used, sufficient plating bath coating film and ink were not obtained.

Based on the above phenomenon, the main object of the present invention is to provide an aluminum flake pigment which is excellent in metallic luster, has a fine grain, and has an appearance of an advanced plating bath such as silver.

In addition, another object of the present invention is to be produced by excellent grinding of the metal, fine grain, appearance of a high-quality plating bath such as silver, and at the same time, by wet grinding the sprayed aluminum powder using a ball mill or the like. The reason is to provide a low cost aluminum flake pigment.

Another object of the present invention is to provide a coating composition and an ink composition which are excellent in metallic luster, have a good texture, and have an appearance of an advanced plating bath such as silver. Furthermore, another further object of the present invention is to provide a coating film which is excellent in metallic luster, has a fine grain, and has an appearance of an advanced plating bath such as silver.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, the present inventors made the relationship of the shape, surface smoothness, average particle diameter, particle diameter distribution, average thickness, thickness distribution, aspect ratio, etc. of aluminum flake pigment, the reflectance of the coating film containing this aluminum flake pigment, etc. It was examined in detail.

As a result, the present inventors have found that, by the aluminum flake pigment having a specific average particle diameter and a specific average thickness, a coating film having excellent metallic luster, fine grains, and an appearance of an advanced plating bath such as silver is obtained. In addition, as a result of studying such a method for producing an aluminum flake pigment, the present invention finds that the aluminum powder produced by the spraying method is wet milled using a ball mill or the like, whereby it can be manufactured at a low manufacturing cost, thereby completing the present invention. I was.

That is, in the present invention, aluminum obtained by grinding aluminum powder in an organic solvent has an average thickness (t) in the range of 0.025 µm to 0.08 µm and an average particle diameter (D ₅₀ ) in the range of 8 µm to 30 µm. Flake pigment. Here, the aluminum powder is preferably aluminum powder produced by the spray method.

Moreover, this invention contains the coating composition containing the said aluminum flake pigment, a binder, and a solvent. Furthermore, this invention contains the ink composition containing the said aluminum flake pigment, a binder, and a solvent.

And this invention includes the coating film obtained by drying after apply | coating the said coating composition to a base material. In addition, the present invention includes a coating film obtained by drying the ink composition on a substrate and then drying.

Best Mode for Carrying Out the Invention

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail by embodiment.

The present invention is an aluminum flake pigment having an average thickness (t) in the range of 0.025 µm to 0.08 µm and an average particle diameter (D ₅₀ ) in the range of 8 µm to 30 µm.

<Average Thickness of Aluminum Flake Pigment>

In order for the aluminum flake pigment of the present invention to have an excellent metallic luster, have a good texture, and have an appearance of an advanced plating bath such as silver, the average thickness (t) of the aluminum flake pigment particles should be in the range of 0.025 to 0.08 µm. And it is preferable to exist in the range of 0.04-0.07 micrometer.

When the average thickness exceeds 0.08 µm, the smoothness of the surface of the aluminum flake pigment particles is insufficient, the metallic luster decreases, the hiding power is insufficient, and the fineness of the grain of the printing surface or the coating film is different from the conventional metallic pigment. There is a problem that does not look, and is not finished with a luxurious plating bath such as silver.

On the other hand, when the average thickness is less than 0.025 µm, the strength of the aluminum flake pigment particles becomes so weak that, during the preparation of the coating composition or the ink composition, breakage or bending of the aluminum flake pigment particles increases, so that a rigid printing layer or coating film cannot be formed. In addition, there is a problem that the production is practically impossible because the time required for grinding.

In addition, the average thickness mentioned in this specification is determined by the measurement using an atomic microscope.

<Average Particle Diameter of Aluminum Flake Pigment>

The average particle diameter (D ₅₀₎ of the aluminum flake pigment of the present invention be in the range of 8 to 30㎛, and is preferably in the range of 10 to 25㎛. Here, aluminum flake pigments with a small average particle diameter generally tend to be difficult to obtain high luminance. Therefore, when the average particle diameter is less than 8 µm, strong metallic luster and high reflectance cannot be obtained. On the other hand, when the average particle diameter exceeds 30 µm, high quality grains of the printing surface and the coating film cannot be obtained. The sparkling luster is so accentuated that it is not finished with a luxurious plating bath like silver.

In addition, the average particle diameter mentioned in this specification is measured using the Microtrac HRA by Honeywell.

Raw material aluminum powder

The sprayed aluminum powder which becomes the raw material of the aluminum flake pigment of this invention is an aluminum powder obtained by the conventionally well-known spraying method, The spray medium is not specifically limited, For example, air, nitrogen, argon gas, Carbon dioxide gas, helium gas, and mixed gas containing one or more of these gases can be used. Moreover, liquids, such as water, can also be used as a spray medium. Among these spraying mediums, aluminum powder obtained by the spraying method using argon gas or nitrogen gas is particularly preferable.

The shape of the sprayed aluminum powder used for this invention is not specifically limited, For example, although it may be any of spherical shape, flat shape, plate shape, cumulative shape, needle shape, spheroid shape, and indefinite shape, It is preferable to be close to a sphere.

Moreover, although the amount of oxygen contained in the said aluminum powder changes also with the particle diameter and shape of the said aluminum powder, 0.5 mass% or less is preferable. When the amount of oxygen exceeds 0.5% by mass, the oxide film is hardened, and there is a tendency for the manufacture of thin flakes to be difficult due to the decrease in ductility.

Moreover, the purity except the oxygen of the said aluminum powder is not specifically limited, Pure aluminum may be sufficient and a well-known aluminum alloy may be sufficient. However, in the gloss surface of a coating film or printed matter, the use of ordinary pure aluminum is preferable, and it is more preferable if it is pure aluminum with a purity of 99.9 mass% or more.

It is preferable that the size of the said aluminum powder exists in the range of 1-10 micrometers, and it is still more preferable if it exists in the range which is 2-8 micrometers. When the average particle diameter is less than 1 µm, the aluminum powder tends to be difficult to flake by grinding, and when the average particle diameter exceeds 10 µm, the grinding time is extremely long and the gloss may be lowered.

<Method for producing aluminum flake pigment>

The production method of the aluminum flake pigment of the present invention is not particularly limited and may be produced by a conventionally known method, but, for example, using a sprayed aluminum powder as a raw material and using a ball mill in the presence of an organic solvent It is preferable to grind for 10 hours or more.

As a grinding device used in the ball mill used by the manufacturing method of the aluminum flake pigment of this invention, a conventionally well-known industrial grinding ball can be used, For example, steel or stainless steel in the range of 0.3-4 mm in diameter. Spheres etc. can be used preferably.

Although the quantity of the said grinding | polishing ball changes also with the size and rotation speed of a ball mill, it is preferable to exist in the range of 40-150 mass parts with respect to 1 mass part of aluminum powder normally. The rotational speed of the ball mill (commonly referred to as a rotational speed) is appropriately changed depending on the size of the ball mill, the material of the ball, the ball diameter, the amount of the ball, and the like, but is usually in the range of 30 to 95% of the critical rotational speed.

As a method for producing the aluminum flake pigment of the present invention, a method of employing a two-stage grinding method in which a raw material aluminum powder is ground in a ball mill and then continues to be milled again using a filter cake obtained by solid-liquid separation using a filter press or the like is preferable. . In the first stage grinding, the raw aluminum powder is effectively increased to some extent, and in the second stage grinding, the grinding conditions are different from those in the first stage in order to avoid the fragmentation of the aluminum particles during flake formation and to slice them more efficiently. It is desirable to change. Specifically, in the second stage grinding, the thinning of the grinding balls can be made small, or the amount of the organic solvent at the time of grinding can be increased, whereby the flaking can be progressed while avoiding the segmentation of the aluminum particles during flake formation.

The grinding | polishing aid used in the manufacturing method of the aluminum flake pigment of this invention is not specifically limited, A conventionally well-known thing can be used, For example, lauric acid, myristic acid, palmitic acid, stearic acid, arachnic acid, Higher fatty acids such as behenic acid, higher unsaturated fatty acids such as oleic acid, higher aliphatic amines such as stearinamine, higher aliphatic alcohols such as stearyl alcohol and oleyl alcohol, higher fatty acid amides such as stearamide, oleic acid amide and stearic acid And higher fatty acid metal salts such as aluminum and aluminum oleate.

It is preferable to use the said grinding | polishing aid in the range of 0.1-10 mass% with respect to raw material aluminum powder, and it is more preferable to use in the range which is 0.2-5 mass%. When the amount of the grinding aid is less than 0.1% by mass, when the specific surface area of the raw aluminum powder is increased by grinding, the grinding aid is insufficient, and aluminum particles during flake formation tend to aggregate. On the other hand, when the amount of the grinding aid is more than 10% by mass, there is a risk of adversely affecting the appearance and durability of the coating film and the printed layer.

The grinding solvent used in the manufacturing method of the aluminum flake pigment of this invention is not specifically limited, A conventionally well-known solvent can be used, For example, Hydrocarbons, such as mineral spirit and solvent naphtha, are mentioned. Alcohol solvents, alcohol solvents, ether solvents, ketone solvents and ester solvents can be preferably used. Among the above-mentioned solvents, the use of high boiling point hydrocarbon solvents such as mineral spirits and solvent naphtha is particularly preferable from the viewpoint of safety. And it is preferable that the quantity of the grinding | polishing solvent with respect to 100 mass parts of raw material aluminum powder exists in the range of 250-2000 mass parts.

And in the manufacturing method of the aluminum flake pigment of this invention, a grinding | polishing apparatus is not limited to a ball mill as mentioned above, It can manufacture suitably also by conventionally well-known grinding apparatuses, such as a wear machine and a vibration mill.

The aluminum flake pigment of the present invention is usually formulated and sold and distributed in solvents such as mineral spirit, solvent naphtha, toluene or ethyl acetate, but it is also possible to remove these solvents and distribute them in a small amount. It can also be wet-treated and marketed.

Coating Compositions and Ink Compositions

The aluminum flake pigments of the present invention are blended with paint compositions, ink compositions, rubber compositions, plastic compositions, elastomer compositions, and the like to give these compositions excellent metallic luster, smooth texture, and give the appearance of a high-quality plating bath such as silver. Can be.

The coating composition and ink composition of the present invention contain the aluminum flake pigment, solvent and binder of the present invention. It is preferable to mix | blend the aluminum flake pigment of this invention in the range of 0.1-30 mass% in the coating composition and ink composition of this invention. Moreover, another coloring pigment and dye can be added to the coating composition and ink composition of this invention as needed.

The solvent used for the coating composition and the ink composition of the present invention is not particularly limited, and conventionally known solvents can be used, for example, aliphatic hydrocarbons such as mineral spirit, hexane, heptane, cyclohexane, octane, benzene, toluene, Aromatic hydrocarbons such as xylene, halogenated hydrocarbons such as chlorobenzene, trichlorobenzene, perchloroethylene and trichloroethylene, alcohols such as methanol, ethanol, n-propyl alcohol and n-butanol, n-propanone and 2- Ketones such as butanone, esters such as ethyl acetate and propyl acetate, ethers such as tetrahydrofuran, diethyl ether and ethyl propyl ether, and other terebin oil. In addition, the said solvent can be used individually or in mixture of 2 or more types.

In addition, although the said description is a case where a solvent is an organic solvent, the solvent used for the coating composition and ink composition of this invention may be water. In this case, the aluminum flake pigment of the present invention can be coated with a resin composition or a phosphorus compound, and then blended with a binder and water, so that it can be used as an aqueous coating composition or ink composition.

The binder used in the coating composition and the ink composition of the present invention is not particularly limited, and conventionally known resins for forming a coating film can be preferably used. Examples thereof include acrylic resins, polyester resins, alkyd resins, and fluorides. Carbon resin etc. can be mentioned and can also be used with crosslinking agents, such as an amino resin and a block polyisocyanate resin. In addition to these resins, lacquers, two-component polyurethane-based resins or silicone-based resins which are cured by natural drying can also be used. In the case of the binder used for the ink composition of the present invention, oils such as linseed oil or castor oil, natural resins such as phenol resin, rosin, and the like may be appropriately blended as necessary. In addition, the said binder can be used individually or in mixture of 2 or more types.

In addition, the coloring pigment which can be added to the coating composition and the ink composition of the present invention is not particularly limited, and conventionally known coloring pigments can be added to such an extent that they do not impair the characteristics of the present invention. For example, quinacridone Organic pigments such as red, phthalocyanine blue, phthalocyanine green, isoindolinone yellow, carbon black, perylene, azolake, inorganic pigments such as iron oxide, titanium oxide, cobalt blue, zinc oxide, ultramarine blue, chromium oxide, mica, sulfur lead, etc. Can be preferably used. In addition, the said coloring pigment is not limited to 1 type, You may use it, mixing 2 or more types or adding simultaneously.

In addition, the coating composition and the ink composition of the present invention include ultraviolet absorbers, thickeners, static eliminators, dispersants, antioxidants, photocatalysts, surfactants, synthetic preservatives, lubricants, plasticizers, curing agents, reinforcing agents such as fillers, waxes and the like. You may add as needed.

<Coating Method of Coating Composition and Printing Method of Ink Composition>

As a method of coating the coating composition of the present invention, a conventionally known method may be employed, and examples thereof include a brush coating method, a spray method, a doctor blade method, a roll coater method, a bar coater method, and the like. Moreover, as a method of printing using the ink composition of this invention, concave-plate printing methods, such as gravure printing, offset printing (also called transfer printing), convex printing methods, such as screen printing, flat printing methods, etc. are mentioned.

The base material as the coating material of the coating composition and the ink composition of the present invention is not particularly limited and can be suitably used as long as it is an article to which the coating composition can be applied. For example, a body such as an automobile, a two-wheeled vehicle, a bicycle, and other vehicles and Optical components such as parts, cameras, video cameras, OA equipment, sports goods, containers such as cosmetics, acoustic products such as radio cassette recorders and CD players, and household goods such as vacuum cleaners, telephones, and televisions.

Moreover, the material of the said base material is not specifically limited, either conventionally well-known thing can be used, For example, inorganic materials, such as ceramics, glass, cement, and concrete, plastic materials, such as a natural resin and a synthetic resin, metal, wood, and paper Etc. can be mentioned.

Hereinafter, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.

<Example 1>

Into a ball mill with an inner diameter of 500 mm and a length of 180 mm, a compound consisting of 1 kg of sprayed aluminum spherical powder having an average particle diameter of 3 μm, 6 liters of mineral spit and 100 g of oleic acid was charged, and 50 kg of steel balls having a diameter of 1.8 mm were used. 1st grinding | pulverization was performed over 8 hours at 33 rpm (equivalent to 55% of critical rotation speed).

After the first stage grinding, the slurry in the ball mill was washed with mineral spirits and solid-liquid separated by a pan filter. Thereafter, 500 g of the obtained filter cake (85% of non-volatile content) was returned to the same type of ball mill in which 50 kg of steel balls having a diameter of 1.5 mm were added in terms of aluminum metal powder. 2nd stage grinding | pulverization was performed over 20 hours with 67% of critical rotation speed.

After completion of the second stage grinding, the slurry in the ball mill was rinsed with mineral spirits, filtered sequentially with a screen of 400 mesh and 500 mesh, and the resulting cake was transferred to a kneader mixer to transfer aluminum flake pigment of 30% of non-volatile content. The paste containing was obtained.

<Example 2>

Except having performed the 2nd step grinding with the steel ball of diameter 1.0mm, the same conditions as Example 1 were employ | adopted, and the paste containing an aluminum flake pigment was obtained.

<Example 3>

Except having used the sprayed aluminum spherical powder with an average particle diameter of 5 micrometers as a raw material, the same conditions as Example 1 were employ | adopted and the paste containing an aluminum flake pigment was obtained.

<Example 4>

The same conditions as in Example 1 were employed except that sprayed aluminum spherical powder having an average particle diameter of 5 µm was used as a raw material, and the second stage grinding was performed with a steel ball having a diameter of 1.0 mm. A paste was obtained.

Example 5

Except having made the grinding time of a 2nd step into 30 hours, the same conditions as Example 1 were employ | adopted, and the paste containing an aluminum flake pigment was obtained.

Comparative Example 1

Except having made the grinding time of the 2nd step into 8 hours, the same conditions as Example 1 were employ | adopted, and the paste containing an aluminum flake pigment was obtained.

Comparative Example 2

The same conditions as in Example 1 were employed except that the spherical aluminum spherical powder having an average particle diameter of 10 µm was used as a raw material, and a paste containing an aluminum flake pigment was obtained.

Comparative Example 3

As a comparative example, Toyo Aluminum Co., Ltd. make, and metasine KM1000 (deposited aluminum flake pigment) were employ | adopted, and it used as an aluminum flake pigment as it is, without processing.

<Evaluation result>

The average thickness and average particle diameter of each aluminum flake pigment obtained in Examples 1-5 and Comparative Examples 1-3, and the reflectance of the coating film of the coating composition containing this aluminum flake pigment are measured below (i)-( iii) measured and evaluated according to. The evaluation results are shown in Table 1.

(i) Average thickness: measuring method of t (μm)

The aluminum paste or aluminum flake pigment containing the aluminum flake pigment is sufficiently washed with acetone and then dried sufficiently to obtain aluminum powder. The obtained aluminum powder was uniformly dispersed on a glass plate, and measured about the thickness of ten particles by the probe microscope (The Seiko Instruments Co., Ltd. product, Nanopics 1000), and made the average value into the average thickness.

(ii) Average particle diameter: measuring method of D ₅₀ (μm)

The mixture which consists of the following formulations was stirred with the glass rod, and it injected | thrown-in to the circulation water in the measurement system of the laser diffraction particle diameter distribution measuring apparatus (microtrack HRA), and disperse | distributed by ultrasonic for 30 second, and measured.

Aluminum paste: 0.5 g

Triton x-100 (* 1): 1.0 g

Ethylene Glycol: 5.0g

However, in the said combination, the product shown by * 1 is a nonionic surfactant made from Union Carbide Corporation.

(iii) Measuring method of reflectance (%) of coating film

After stirring the mixture which consists of the following mixture with a glass rod, it spray-coated to an aluminum plate at 1.0 kg / cm <2> of pneumatic pressures, and after baking for 20 minutes at 80 degreeC, the grossmeter (made by Tokyo Denshoku Co., Ltd., TC-108DP) ), The gross value is measured at an incident angle of 60 ° and a light receiving angle of 60 °.

Aluminum flake pigment: 1.0 g (in terms of metal powder)

Polytack 3000 (* 2): 6.67 g

Polytack Thinner (* 2): 100g

However, in the said mixture, the goods represented by * 2 are Tohokaken Co., Ltd. product, acrylic lacquer clear resin.

Particle Thickness of Aluminum Flake Pigments (μm) Average Particle Diameter of Aluminum Flake Pigment (μm) Reflectance of Coating Film (%) Example 1 0.045 12.8 80 Example 2 0.063 13.8 84 Example 3 0.050 16.3 92 Example 4 0.060 18.9 74 Example 5 0.030 10.1 82 Comparative Example 1 0.103 13.1 61 Comparative Example 2 0.513 32.3 52 Comparative Example 3 0.025 11.1 115

As shown in Table 1 of the above evaluation results, the coating film using the coating material containing the aluminum flake pigments of Examples 1 to 5 clearly has a high reflectance compared to Comparative Examples 1 and 2, and the aluminum vapor deposition flake pigment of Comparative Example 3 It does not reach the case of use, but it shows very close value.

The disclosed embodiments and examples are to be considered in all respects only as illustrative and not restrictive. The scope of the present invention is disclosed not by the above description but by the claims, and includes all changes within the meaning and range equivalent to the scope of the claims.

From the above evaluation results, the aluminum flake pigment of the present invention has a high reflectance, so that even a very thin coating film is excellent in metallic gloss, has a good texture, and obtains a high-quality gloss of a plating bath such as silver, and undergoes a deposition process. Because it is manufactured without, it is suitable for mass production at low cost.

Since the coating composition and ink composition using the aluminum flake pigment of this invention have a high reflectance, even a very thin coating film and a printed layer are excellent in metal gloss, have a good texture, and obtain the high gloss of a plating bath like silver.

Moreover, since the coating film and printed layer using the aluminum flake pigment of this invention have a high specular reflectance, it is excellent in metallic luster, it is grainy, and the luxurious appearance of the plating bath like silver can be obtained.

Claims (10)

A method for producing an aluminum flake pigment, wherein the average thickness (t) is in the range of 0.025 μm to 0.08 μm and the average particle diameter (D ₅₀ ) is in the range of 8 μm to 30 μm, comprising the following steps: 1) a first step of producing an aluminum powder having an average particle diameter in the range of 1 µm to 10 µm by a spraying method; And 2) A second step of grinding the aluminum powder in an organic solvent, wherein the second step is processed using a grinding device having a diameter in the range of 0.3 mm to 4 mm. delete delete delete delete delete The method of claim 1, wherein the second step is processed for at least 10 hours. The method of claim 1, wherein the second step is processed for at least 28 hours. The method according to claim 1, wherein the amount of oxygen contained in the aluminum powder is 0.5 mass% or less. The method according to claim 1, wherein the second step is processed by a two-stage grinding method in which the aluminum powder is ground, solid-liquid separated and then continued to be ground again.