JP6982963B2 - Reefing aluminum pigments, methods for producing leafing aluminum pigments, paint compositions containing reefing aluminum pigments, coating films, articles having the coating films, ink compositions, and printed matter. - Google Patents

Description

The present invention relates to a leaving aluminum pigment, a method for producing leaving aluminum, a coating composition containing a leaving aluminum pigment, a coating film, an article having the coating film, an ink composition, and a printed matter.

Conventionally, aluminum pigments have been widely used in various fields as pigments having a unique metallic feeling not found in other pigments and an excellent hiding power against the substrate.
Especially in the field where chrome-like design is required, reefing aluminum pigment is preferably used, but in this field as well, it is necessary to improve the design such as fineness, brightness, gloss, etc. and realize excellent appearance characteristics. Is required.
As a method for realizing the excellent appearance characteristics as described above, there is a method of atomizing the particles of the aluminum pigment. It is known that making the particles of the aluminum pigment into fine particles is effective in improving the feeling of fineness.
However, when the particles of the aluminum pigment are made into fine particles, there is a problem that the orientation of the particles in the coating film is lowered, the brightness is lowered, and the generation of scattered light is increased.

As a method for improving such a problem, a method of thinning aluminum particles can be mentioned.
For example, Patent Document 1 discloses an aluminum pigment capable of thinning aluminum particles, excellent metallic luster, and realizing a plating-like appearance by lengthening the grinding time of the raw material aluminum powder.
Further, Patent Document 2 and Patent Document 3 disclose a predetermined thin-film aluminum pigment, and by specifying the thickness distribution (range of relative width Δh) and aspect ratio of aluminum particles, dispersibility We are trying to improve workability such as.
Further, Patent Document 4 discloses a method for manufacturing an aluminum pigment by a metal vapor deposition method, and in the manufacturing method, a manufacturing method completely different from that of an aluminum pigment by machining using a crusher is adopted. , The aluminum particle thickness is set to be thin and a single thickness, and the smoothness is also very excellent, and it is possible to obtain a feeling of fineness, high brightness, and high gloss.

Japanese Unexamined Patent Publication No. 2003-82258 Japanese Unexamined Patent Publication No. 2014-159583 International Publication No. 2004/08781 Pamphlet Special Table 2002-528639

In the field of industrial products that require a high-class feel, such as automobiles, home information appliances, cosmetic containers, or the field of lamp reflectors that require high reflectance, there is a demand for precise and high-brightness chrome-like designs using leafing aluminum pigments. Is increasing.
Further, in the field of high-grade printing inks such as offset printing and screen printing, there is an increasing demand for precise and high-brightness mirror-like metallic designs.

However, the aluminum pigments described in Patent Documents 1 to 3 described above obtain excellent metallic luster by forming aluminum particles thinly stretched, but have a high degree of fineness and a specular reflection region. From the viewpoint of realizing all of the brightness and the suppression of scattered light, there is a problem that sufficient characteristics have not been obtained yet.
Further, the aluminum pigment described in Patent Document 4 also has a high fineness and high brightness by being manufactured by the vapor deposition method, but similarly to the above, the high fineness and the brightness in the specular reflection region are obtained. From the viewpoint of realizing all of the suppression of scattered light, there is a problem that sufficient characteristics have not yet been obtained.
As described above, none of the conventionally proposed techniques has a problem that an aluminum pigment capable of achieving high precision, brightness in a specular region, and suppression of scattered light cannot be obtained. is doing.

Further, the leaving aluminum pigment has a feature that aluminum particles float on the upper layer of the coating film to form an aluminum particle layer, and this continuous aluminum particle layer enables a dense chrome-like design. On the other hand, the conventional aluminum pigment has a problem that the continuous layer of aluminum particles in the uppermost layer of the coating film has irregularities and the gloss of the coating film is lowered.

Therefore, in the present invention, in view of the above-mentioned problems of the prior art, a chrome-like metallic design having a high degree of precision, extremely high brightness in the specular reflection region, and high gloss is realized. It is an object of the present invention to provide an aluminum pigment.

As a result of diligent studies on the above-mentioned problems of the prior art, the present inventors focused on the cross-sectional shape of the particles of the leafing aluminum pigment, and the flatness (shortest) of the particles with respect to the cross-sectional shape of the particles in the cross section of the coating film. By setting the ratio of planar particles in the range of 0.95 to 1.00 (length / cross-sectional length of particles) to a specific range, and further setting the average particle diameter (d50) to a specific range, a high degree of fineness is achieved. The present invention has been completed by finding that a leaving aluminum pigment that can realize a chrome-like metallic design having extremely high brightness in a positive reflection region and having high gloss can be obtained. ..
That is, the present invention is as follows.

[1]
A leafing aluminum pigment comprising particles child is ground product of ball diameter 0.6Emufai～2.4Emufai,
The average particle diameter d50 of the particles is 4 μm to 15 μm, and
Of the 100 particles obtained by the FE-SEM image, which are particles having an average particle diameter d50 ± 50% or less, the length of connecting both tips of the particle cross section with a straight line is defined as the shortest length, and both tips are defined as the shortest length. When the length of the line connected along the cross section of the particle is taken as the cross-sectional length of the particle, the flat particle having a planarity (shortest length / cross-sectional length of the particle) of 0.95 to 1.00 is defined as 100. 60% of the particles
It is contained in a number ratio of ~ 100%,
A reefing aluminum pigment having a reefing value of 82 or more according to JIS K 5906.
[2]
The reefing aluminum pigment according to the above [1], wherein the average thickness t of the particles is 0.03 μm to 0.12 μm.
[3]
The ratio (d50 / t) of the average particle diameter d50 (μm) to the average thickness t (μm) of the particles.
The reefing aluminum pigment according to the above [1] or [2], wherein the number is 90 to 250.
[4]
The reefing aluminum pigment according to any one of [1] to [3] above, wherein the surface roughness Ra of the particles is 2 to 12 nm.
[5]
The reefing aluminum pigment according to any one of the above [1] to [4], which has a reefing value of 86 or more.
[6]
The method for producing a reefing aluminum pigment according to any one of [1] to [5] above.
A method for producing a reefing aluminum pigment, which comprises a step of grinding atomized aluminum powder with a grinding device equipped with a ball mill having a diameter of 0.6 mφ to 2.4 mφ.
[7]
A coating composition containing the reefing aluminum pigment according to any one of [1] to [5].
[8]
A coating film containing the coating composition according to the above [7].
[9]
An article having the coating film according to the above [8].
[10]
An ink composition containing the reefing aluminum pigment according to any one of [1] to [5].
[11]
A printed matter containing the ink composition according to the above [10].

According to the present invention, it is possible to provide a leaving aluminum pigment capable of realizing a chrome-like metallic design having a high degree of fineness, extremely high brightness in a specular reflection region, and high gloss.

Photograph of FE-SEM image of particle cross section of aluminum pigment obtained by using field emission type FE-SEM (manufactured by HITACHI / S-4700) to explain a method for evaluating the flatness of aluminum pigment particles. An example is shown. (A) A schematic diagram of an example of the state of the reefing aluminum pigment in the coating film is shown. (B) The schematic diagram of an example of the state in a coating film of a non-reefing aluminum pigment is shown.

Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail.
The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be appropriately modified and carried out within the scope of the gist thereof.

[Reefing aluminum pigment]
In the leaving aluminum pigment of the present embodiment, the average particle diameter d50 of the particles is 4 μm to 15 μm, and the planarity (shortest length / cross-sectional length of the particles) of the particles is 0.95 to 1.00. Is contained in a number ratio of 60% to 100%, and the leafing value according to JIS K 5906 is 82 or more.

The leaving aluminum pigment is a type of aluminum pigment in which the particles float on the surface of the coating film due to the surface tension of the particles.
FIG. 2A shows a schematic diagram of an example of the state of the reefing aluminum pigment in the coating film, and FIG. 2B shows a schematic diagram of an example of the state of the non-reefing aluminum pigment in the coating film.
In the leaving aluminum pigment of the present embodiment, the average particle diameter d50 of the particles, the flatness of the particles (shortest length / cross-sectional length of the particles), and the average thickness t (μm) are defined as follows.

The average particle diameter d50 (μm) of the particles is a median diameter, and the average particle diameter d50 can be measured by using a laser diffraction / scattering type particle size distribution measuring device.
The average particle size d50 of the particles of the reefing aluminum pigment of the present embodiment is 4 μm to 15 μm.
The average particle diameter d50 of the particles of the leaving aluminum pigment of the present embodiment may be within the above numerical range, and fine particles and small particles may be selected according to the finally desired design.
When the average particle diameter d50 of the particles is 4 μm or more, the particles are oriented in a certain direction in the coating film using the leaving aluminum pigment of the present embodiment, light scattering can be reduced, and the brightness is also high. It is preferable.
Further, when the average particle diameter is 15 μm or less, it is easy to adjust the flatness (shortest length / particle cross-sectional length) of the particles described later to a preferable range, and it is possible to obtain a metallic coating film having a dense feeling, which is preferable. ..
The average particle size (d50) of the particles of the reefing aluminum pigment of the present embodiment is preferably 5 μm or more and 13 μm or less, and more preferably 6 μm or more and 12 μm or less.
The average particle size d50 of the leafing aluminum pigment is the particle size of the raw material atomized aluminum powder and the particle size of the ground ball in the step of grinding the raw material atomized aluminum powder using a ball mill in the method for producing the leaving aluminum pigment described later. It can be controlled by appropriately adjusting the mass per piece and the number of rotations of the grinding device.

For the flatness (minimum length / particle cross-sectional length) of the particles of the leaving aluminum pigment of the present embodiment, an FE-SEM image of a cross section of a coating film formed by the coating composition containing the leaving aluminum pigment of the present embodiment is obtained. It can be obtained by measuring the cross-section with image analysis software.
The measurement method will be described.
In the FE-SEM image of the cross section of the coating film, the measured value connecting both ends of the particle cross section with a straight line is defined as the "shortest length". Further, the measured value of the line connecting both ends of the particle cross section along the shape of the particle cross section is defined as the “particle cross section length”.
The value of the ratio of the shortest length to the particle cross-sectional length (shortest length / particle cross-sectional length) is defined as the flatness of the particle.
The flatness of the particles indicates that the closer to 1.00, the smaller the warpage / distortion of the particles.
The flatness of 100 particles is determined by the above definition.
Regarding the degree of flatness of particles, the threshold for distinguishing is set to 0.95, particles in the range of 0.95 to 1.00 are defined as flat particles, and the ratio is determined as (%: number ratio).
The preparation of the coating film cross section, the acquisition of the FE-SEM image, and the image analysis can be carried out by the methods described in Examples described later.

The reefing aluminum pigment of the present embodiment contains 60% to 100% of the above-mentioned planar particles having a planarity in the range of 0.95 to 1.00.
When the ratio of the planar particles is 60% or more, the brightness in the specular reflection region can be increased and the scattered light can be reduced, and a preferable design can be obtained.
That is, in the leaving aluminum pigment of the present embodiment, the brightness in the specular region is extremely high by containing 60% to 100% of the particles having a planarity in the range of 0.95 to 1.00, and further. A mirror-like metallic design with very little scattered light can be obtained.
The content ratio of the particles having a planarity in the range of 0.95 to 1.00 is preferably 65% or more and 98% or less, and more preferably 70% or more and 98% or less.
When the ratio of the planar particles is 100% or less, the grinding time required for producing the aluminum pigment of the present embodiment is not extremely long, and the productivity is excellent.

The reefing aluminum pigment of the present embodiment has a reefing value of 82 or more, preferably 84 or more, and more preferably 86 or more.
When the leafing value is 82 or more, the flatness and smoothness of the particles in the aluminum pigment are improved, the unevenness of the continuous layer of aluminum particles in the uppermost layer of the coating film is reduced, and the gloss of the coating film is improved.
Reefing value is measured based on JIS K 5906. Specifically, it can be measured by the method described in Examples.
The reefing value of the particles can be controlled to 82 or more by using an appropriate amount of a grinding aid at the time of grinding and maintaining the slurry temperature at 50 ° C. or lower.

The average thickness t (μm) of the particles of the leaving aluminum pigment of the present embodiment shall be measured by using the FE-SEM image of the cross section of the coating film applied in the measurement of the flatness of the particles and by using image analysis software. Can be obtained by.
Specifically, it can be obtained by randomly selecting 100 particles in the FE-SEM image of the cross-section of the coating film, performing automatic measurement of the cross-sectional thickness of the particles, and calculating the arithmetic mean value of 100 particles. ..
The average thickness t (μm) of the particles of the reefing aluminum pigment of the present embodiment is preferably 0.03 μm to 0.12 μm.
When the average thickness t is 0.03 μm or more, it becomes easy to control the flatness (shortest length / particle cross-sectional length) of the above-mentioned particles in the range of 0.95 to 1.00, and the specular reflection region. It is preferable because the brightness of the light is high and the scattered light can be reduced.
When the average thickness t of the particles is 0.12 μm or less, the shaded area at the end of the particles can be suitably adjusted, a feeling of fineness can be obtained, and scattered light can be reduced, which is preferable.
The average thickness t (μm) of the particles of the leaving aluminum pigment of the present embodiment is more preferably 0.03 μm or more and 0.10 μm or less, and further preferably 0.04 μm or more and 0.09 μm or less.
The average thickness t of the leaving aluminum pigment is the mass per grinding ball and the weight of the grinding device in the step of grinding the raw atomized aluminum powder using a ball mill in the method for producing the leaving aluminum pigment described later. It can be controlled by appropriately adjusting the number of rotations.

The ratio (d50 / t) of the average particle diameter d50 to the average thickness t of the particles of the leaving aluminum pigment of the present embodiment is the aspect ratio of the aluminum particles, and in the present embodiment, the aspect ratio is 90 to 250. Is preferable.
When the aspect ratio is 90 or more, higher brightness in the specular reflection region and higher hiding power can be obtained, and when used for thin film coating, a mirror-like and high-class feeling can be obtained in the coating film.
Further, when the aspect ratio is 250 or less, warpage, distortion, and cracking of the particles can be prevented, the particles are not broken, and the generation of scattered light can be extremely reduced.
The aspect ratio (d50 / t) of the particles of the reefing aluminum pigment of the present embodiment is more preferably 100 or more and 250 or less, and further preferably 130 or more and 250 or less.

The average roughness Ra of the surface of the particles of the leafing aluminum pigment of the present embodiment is an index showing the smoothness of the surface of the particles of the aluminum pigment, and is measured by an SPM (Scanning Probe Microscope) including an atomic force microscope or the like. Can be done.
In the reefing aluminum pigment of the present embodiment, the average roughness Ra of the particles is preferably 2 to 12 nm.
Since the smoothness of the particle surface is high when the average roughness Ra is 12 nm or less, the amount of specularly reflected light is high, and a higher luminance feeling can be obtained. Further, when the average roughness Ra is 2 nm or more, the grinding time required for producing the reefing aluminum pigment of the present embodiment is not extremely long, and the productivity is excellent.
This Ra is more preferably 2 to 10 nm, and even more preferably 2 to 8 nm.

[Manufacturing method of reefing aluminum pigment]
The method for producing the reefing aluminum pigment of the present embodiment described above will be described below.
The reefing aluminum pigment of the present embodiment has a step of grinding atomized aluminum powder by a grinding device equipped with a ball mill.
Adjust and combine the conditions such as increasing the particle size of the atomized aluminum powder used as the raw material, reducing the mass of each grinding ball, and reducing the rotation speed of the grinding device. Therefore, the proportion of flat particles having the above-mentioned flatness (minimum length / particle cross-sectional length) of 0.95 to 1.00 can be increased.
In addition, conditions such as increasing the mass of each grinding ball, increasing the number of rotations of the grinding device, and reducing the average thickness t of the aluminum pigment particles are appropriately adjusted and combined. Therefore, the ratio of the plane particles can be reduced.
In addition to performing the above operation, the grinding conditions are determined in consideration of adjusting the average particle size (d50) to the range of the present embodiment and improving the productivity.

Considering that the average particle size d50 of the particles in the leaving aluminum pigment of the present embodiment is in the range of 4 μm to 15 μm, a particularly preferable grinding condition is preferably a particle size of 1.5 to 1.5 as a raw material. Using atomized aluminum powder having a particle size of 5.0 μm, more preferably 1.5 to 4.0 μm, the mass per grinding ball used in the grinding apparatus is preferably 0.08 to 11.00 mg. , More preferably 0.08 to 9.00 mg, and a combination of conditions where the rotation speed of the grinder is 33% to 78%, more preferably 36% to 57% with respect to the critical rotation speed (Nc).
By adjusting the impact force applied to the aluminum particles received from the grinding ball by the method described above, and setting the ratio of the average particle diameter d50 (μm) to the average thickness t (μm) of the aluminum particles in the range of 90 to 250. The leaving aluminum pigment of the present embodiment containing 60% to 100% of planar particles having a particle flatness (minimum length / particle cross-sectional length) in the range of 0.95 to 1.00 is obtained.

The specific gravity of the grinding balls used in a ball mill or the like is preferably 8 or less, preferably 7.5 or less, from the viewpoint of facilitating an increase in the proportion of the planar particles and increasing the surface smoothness of the aluminum particles. It is more preferably less than or equal to, and even more preferably 7 or less.
The specific gravity of the grinding balls is preferably larger than the specific gravity of the grinding solvent. Since the specific gravity of the grinding balls is larger than the specific gravity of the grinding solvent, it is possible to prevent the grinding balls from floating in the solvent, sufficient shear stress between the grinding balls is obtained, and grinding proceeds sufficiently. There is a tendency.

As the grinding balls used in the method for producing the leaving aluminum pigment of the present embodiment, those having high surface smoothness such as stainless steel balls, zirconia balls, and glass balls are used for adjusting the surface smoothness of aluminum particles and for grinding balls. It is preferable from the viewpoint of durability.
On the other hand, steel balls, alumina balls and the like having low surface smoothness are not preferable from the viewpoint of adjusting the surface smoothness of aluminum particles and the durability of the ground balls.
Therefore, for example, in the case of stainless steel balls, it is preferable to use stainless steel balls whose surface smoothness has been improved by mechanical polishing and chemical polishing.

As described above, the mass of each grinding ball is preferably 0.08 to 11.00 mg.
By using grinding balls having a mass of 0.08 mg / piece or more, the grinding balls move in groups or in chunks without moving individually, so that the shear stress between the grinding balls is reduced and grinding proceeds. It is possible to prevent the phenomenon that the so-called group motion does not occur.
Further, by using a grinding ball having a mass of 11.00 mg / piece or less, it is possible to prevent an excessive impact force from being applied to the aluminum powder and prevent the occurrence of warpage, distortion, cracks and the like.

As the atomized aluminum powder used as a raw material, a powder having few impurities other than aluminum is preferable.
The purity of the atomized aluminum powder is preferably 99.5% or more, more preferably 99.7% or more, still more preferably 99.8% or more.

The average particle size of the atomized aluminum powder as a raw material is preferably 1.5 to 5.0 μm, more preferably 1.5 to 4.0 μm.
Since the atomized aluminum powder has an average particle size of 1.5 μm or more, the energy applied to the particles during the grinding process does not become excessive, warpage and distortion of the particles can be prevented, and the particle shape can be kept good. preferable.
Further, since the atomized aluminum powder has an average particle size of 5.0 μm or less, the average particle size of the particles of the ground product can be adjusted to 15 μm or less, and the leaving aluminum pigment of the present embodiment is suitable. Tends to be obtained.
As the shape of the atomized aluminum powder as a raw material, those such as spherical powder and teardrop-shaped powder are preferable. By using these, the shape of the aluminum pigment during grinding tends to be less likely to collapse. On the other hand, needle-shaped powder and amorphous powder are not preferable because the shape of the aluminum pigment tends to collapse during grinding.

When producing the reefing aluminum pigment of the present embodiment by a grinding apparatus provided with a ball mill, it is preferable to use a grinding solvent.
The types of the polishing solvent are not limited to the following, but are not limited to, for example, conventionally used hydrocarbon solvents such as mineral spirit and solvent naphtha, alcohol-based, ether-based, ketone-based, and ester-based solvents. Examples thereof include low-viscosity solvents such as.
As the grinding conditions for the atomized aluminum powder, the volume of the grinding solvent is preferably 1.5 to 16.0 times, more preferably 2.0 to 12.0 times the mass of aluminum in the atomized aluminum powder. preferable. When the volume of the grinding solvent is 1.5 times or more the mass of the aluminum of the atomized aluminum powder, it is possible to prevent warpage, distortion, cracks, etc. due to long-term grinding of the atomized aluminum powder, which is preferable. ..
In addition, since the volume of the grinding solvent with respect to the mass of aluminum in the atomized aluminum powder is 16.0 times or less, the uniformity in the mill during grinding is improved, and the atomized aluminum powder becomes the grinding medium. There is a tendency for efficient contact and grinding to proceed favorably.

The volume of the grinding ball (volume of the grinding ball / volume of the grinding solvent) with respect to the volume of the grinding solvent is preferably 0.5 to 3.5 times, preferably 0.8 to 2.5 times. Is more preferable.
When the volume of the grinding ball is 0.5 times or more the volume of the grinding solvent, the uniformity in the mill at the time of grinding is improved, and the grinding tends to proceed favorably.
Further, since the volume of the grinding balls is 3.5 times or less the volume of the grinding solvent, the ratio of the grinding balls in the mill is in a suitable range, and the stacking of the balls does not become too high. It is preferable because the problem of shape deterioration such as warpage, distortion, and crack of particles due to crushing stress can be prevented, and the decrease in brightness and the increase in scattered light can be prevented.

When the reefing aluminum pigment of the present embodiment is produced by a grinding device equipped with a ball mill, a grinding aid is used in order to reduce the reefing value according to JIS K 5906 to 82 or less in addition to the above-mentioned grinding solvent. Is preferable.
The grinding aid may be any as long as it exhibits the characteristics as a leafing aluminum pigment, and is not limited to the following, but is a higher saturated fatty acid typified by, for example, myristic acid, palmitic acid, stearic acid, and arachidic acid. Is preferable. Further, this higher saturated fatty acid can be used in either a linear or branched chain form, but a linear fatty acid is more preferable.
The grinding aid is preferably used in an amount of 0.5 to 15% by mass with respect to the mass of the atomized aluminum powder.
The reefing value can be adjusted by the amount of the grinding aid. When the amount of the grinding aid is 0.5% by mass or more with respect to the mass of the atomized aluminum powder, a sufficient leafing value can be obtained, and when it is 15% by mass or less, excessive grinding is performed. It is possible to prevent the auxiliary agent from remaining in the aluminum pigment, and it is possible to obtain an appropriate coating film. Further, the slurry temperature at the time of grinding also affects the reefing value, and in order to make the reefing value 82 or more, the grinding temperature is preferably 50 ° C. or lower, more preferably 40 ° C. or lower.

The ball mill used for grinding the atomized aluminum powder preferably has a diameter of 0.6 mφ to 2.4 mφ, and more preferably 0.8 mφ to 2.0 mφ.
By using a ball mill having a diameter of 0.6 mφ or more, the lamination of the grinding balls does not become too low, the pressure applied to the aluminum particles during the grinding process is in a suitable range, and the grinding tends to proceed favorably. ..
In addition, by using a ball mill with a diameter of 2.4 mφ or less, the stacking of grinding balls does not become too high, and the problems of shape deterioration such as warpage, distortion, and cracks of particles due to the weight of the balls are prevented, and the brightness is reduced. It is preferable because it can prevent a decrease and an increase in scattered light.

As described above, the rotation speed of the ball mill during grinding of the atomized aluminum powder is preferably 33% to 78%, preferably 36% to 57%, based on the critical rotation speed (Nc). More preferred.
When the ratio of rotation speed / critical rotation speed is 33% or more, the uniformity of the aluminum slurry and ball motion in the ball mill is maintained, which is preferable.
In addition, since the ratio of rotation speed / critical rotation speed is 78% or less, the behavior of the grinding ball being scraped up or falling by its own weight is prevented, and the impact force applied to the aluminum particles received from the grinding ball is prevented. Is not too high, and problems of shape deterioration such as warpage, distortion, and cracks of particles are prevented, which is preferable.

The reefing aluminum pigment of the present embodiment can also be produced by a vacuum vapor deposition method in addition to the production method having the above-mentioned step of grinding the atomized aluminum powder.

[Paint composition]
The coating composition of the present embodiment contains the reefing aluminum pigment of the present embodiment described above.
In the coating composition of the present embodiment, mica, a coloring pigment and the like can be used in combination in addition to the reefing aluminum pigment.
In addition, various resins and various additives such as antioxidants, light stabilizers, polymerization inhibitors, and surfactants may be used in combination with the coating composition of the present embodiment.
The coating composition of the present embodiment can be produced by mixing a reefing aluminum pigment and other various materials, if necessary.
The coating composition of this embodiment can be used as a metallic coating material.

[Coating film, article having the coating film]
The coating film of the present embodiment contains the above-mentioned reefing aluminum pigment of the present embodiment, and can be formed by applying the above-mentioned coating composition to a predetermined substrate.
Various articles can be selected as the base material, and the coating film of the present embodiment can be formed on the desired one by the selected article.
Examples of the article include, but are not limited to, an automobile body, automobile interior parts, home appliances, mobile phones, smartphones, PCs, tablets, cameras, optical devices such as televisions, and the like.
The method for forming the coating film is not particularly limited, and a conventionally known method can be appropriately applied depending on the target article.

[Ink composition, printed matter]
The ink composition of the present embodiment contains the reefing aluminum pigment of the present embodiment described above.
In the ink composition of the present embodiment, in addition to the above-mentioned reefing aluminum pigment, a predetermined coloring pigment, a solvent, or the like can be used in combination.
In addition, various resins and various additives such as antioxidants, light stabilizers, polymerization inhibitors, and surfactants may be used in combination with the ink composition of the present embodiment.
The ink composition of the present embodiment can be produced by mixing a reefing aluminum pigment and various other materials as needed, and can be used as a metallic ink.
Further, the printed matter of the present embodiment contains the reefing aluminum pigment of the above-mentioned embodiment and can be formed by printing using the above-mentioned ink composition. Examples of the printed matter include ink printed matter that forms a coating film by gravure printing, offset printing, screen printing, and the like.

[Other uses]
In addition, the reefing aluminum pigment of the present embodiment can be kneaded with a resin or the like and used as a water-resistant binder or filler.

Hereinafter, the present embodiment will be described in more detail with reference to Examples and Comparative Examples.
The present embodiment is not limited to the following examples.
The methods for measuring various physical properties used in Examples and Comparative Examples are as follows.

[(I) Average thickness of particles: t]
((1) Preparation of painted plate)
Using the aluminum pigments obtained in Examples and Comparative Examples described later, a metallic base paint was prepared with the following composition.
Since the paint system used in this measurement has high wettability to the pigment, the leaving aluminum pigment also exhibits non-leaving behavior, and the aluminum pigment is uniformly dispersed in the coating film.
Aluminum pigment: 2g
Thinner: 50g
(Made by Musashi Paint Co., Ltd., product name "Plaace Thinner No. 2726")
Acrylic resin: 33g
(Made by Musashi Paint Co., Ltd., product name "Plaace No. 7160")
Next, the metallic base paint was applied to an ABS resin plate using an air spray device so that the dry film thickness was 20 μm, and dried in an oven at 60 ° C. for 30 minutes to obtain a metallic base coated plate.
A top coat paint prepared with the following composition was applied onto the metallic base coating plate using an air spray device.
Hitaroid Wanis 3685S (Made by Hitachi Kasei): 25g
Mixed thinner: 20g
(Solvent mixing ratio / toluene: 45% by mass, butyl acetate: 30% by mass, ethyl acetate:
20% by mass, 2-acetoxy-1-methoxypropane: 5% by mass)
Duranate TPA100 (manufactured by Asahi Kasei): 5g
After applying the above-mentioned top coat paint, it was dried in an oven at 60 ° C. for 30 minutes to obtain a coating plate for evaluation.

((2) Creating a cross section of the coating film)
Using the coating plate for evaluation produced in ((1) Preparation of coating plate), a coating film cross section was prepared by the following procedure.
Using scissors, the coating plate for evaluation was divided into 2 cm square pieces.
A large rotary microtome (manufactured by Daiwa Kouki Kogyo / RV-240) was used to repeatedly cut the cross section of the coating film on the divided 2 cm square evaluation coated plate, and the micro aluminum / acrylic resin protruding on the cross section. Was removed.
Using an ion milling device (manufactured by JEOL Ltd./IB-09010CP), the coating film cross section obtained as described above is set so that ion beam irradiation can be performed up to a portion 20 μm away from the coating film cross section, and ion milling treatment is performed. This was performed to prepare a coating film cross section for acquiring an FE-SEM image, which will be described later.

((3) Acquisition of particle cross section (FE-SEM image))
The cross section of the coating film (painted plate) for acquiring the FE-SEM image obtained in ((2) Preparation of the cross section of the coating film) is adhered so as to be parallel to the SEM sample table, and the field emission type FE-SEM is adhered. (Manufactured by HITACHI / S-4700) was used to obtain an FE-SEM image of the cross section of the coating film.
The conditions for FE-SEM observation / acquisition were that the acceleration voltage was adjusted to 5.0 kV and the image magnification was 10,000 times or 5,000 times. The thickness of the particles was measured at a high magnification of 10,000 times. On the other hand, the flatness (shortest length / cross-sectional length of particles), which will be described later, is also suitable for measurement at a high magnification of 10,000 times, but for those with a large particle size that protrudes from the shooting screen, measurement was performed at 5,000 times. ..
Further, before acquiring (capturing) the FE-SEM image, an electronic engineering axis alignment process was performed so that the boundary line between the aluminum particles and the acrylic resin in the FE-SEM image was not distorted.

((4) Analysis (Measurement of average thickness t of particles in particle cross section))
The FE-SEM image obtained in ((3) Acquisition of particle cross section (FE-SEM image)) is obtained from the particles in the aluminum particle cross section using the image analysis software Win Roof version 5.5 (manufactured by MITANI CORPORATION). The average thickness t was measured.
The measurement method is to display an image of the FE-SEM image that measures the thickness of the aluminum particles selected from the file in the cross section, select the ROI line, align the ROI line with the 5 μm scale of the image, and register / change the length.・ Enter the unit and set.
Next, an image in which the thickness of the cross section of the aluminum particles should be measured was displayed, a rectangular ROI was selected, and the rectangular ROI was matched with the cross section of the particles to perform binary processing.
Next, after selecting the measurement item of the vertical chord length of the measurement, the measurement was executed and the automatically measured value (vertical chord length value) by the image analysis software was displayed on the image.
In this way, using the above-mentioned image analysis software Win Roof version 5.5, 100 particles within ± 50% of the average particle size: d50 of [(IV) average particle size: d50] described later were selected. The thickness of the cross section of the aluminum particles was automatically measured, the arithmetic mean value of 100 particles was calculated, and the average thickness t of the particles was obtained.

[(II) Evaluation of particle flatness (shortest length / particle cross-sectional length)]
The SEM image obtained in the procedure for acquiring the ((I)-(3)) particle cross section (FE-SEM image) is aluminum using the image analysis software used in the ((I)-(4)) analysis. The flatness of the particles (shortest length / cross-sectional length of the particles) was evaluated.
FIG. 1 shows an image of an example for evaluating the flatness (shortest length / cross-sectional length of particles) of particles.
Select the straight line tool and curve tool of the image analysis software Win Roof version 5.5, connect both ends of the cross section of the aluminum particle with a straight line to the shortest length, and connect both ends along the cross section of the aluminum particle. The measured value of the polygonal line was defined as the particle cross-sectional length, and the value of (shortest length / particle cross-sectional length) was defined as the flatness of the aluminum particles.
This above procedure was repeated to determine the flatness values of 100 particles.
Further, the aluminum particles selected for obtaining the flatness value were set to be within ± 50% of the average particle diameter: d50 of [IV] described later.
The closer the value of the flatness of the particles is to 1.00, the smaller the degree of warpage, distortion, etc. of the particles.

[(III) Number ratio of planar particles]
From the value of the flatness (shortest length / particle cross-sectional length) of 100 particles obtained in (II) above, the threshold of the flatness of the particles is set to 0.95, and the range is 0.95 to 1.00. The number ratio of the aluminum particles contained in the above was calculated.
In the reefing aluminum pigment of the present embodiment, the number ratio of the planar particles in the range of the planarity of the particles in the range of 0.95 to 1.00 is 60% to 100%.

[(IV) Average particle size: d50]
The average particle size (d50) of the particles of the aluminum pigment was measured by a laser diffraction / scattering type particle size distribution measuring device (LA-300 / HORIBA, Ltd.).
Mineral spirit was used as the measurement solvent.
The measurement was carried out according to the instruction manual of the equipment, but it should be noted that the aluminum pigment used as a sample was ultrasonically dispersed for 2 minutes as a pretreatment, and then put into a dispersion tank to reach an appropriate concentration. After confirmation, measurement was started.
After the measurement was completed, d50 was automatically displayed.

[(V) Aspect ratio (d50 / t)]
The aspect ratio was the value obtained by dividing the average particle size: d50 value measured in (IV) by the average thickness of the particles obtained by the analysis / arithmetic mean value: t (d50 / t).

[(VI) Average surface roughness of particles: Ra]
The average roughness Ra of the surface of the particles of the aluminum pigment was measured by the following method.
((1) Pretreatment)
The aluminum pigments obtained in Examples and Comparative Examples described later were washed because they were mixed with the mineral spirit.
100 mg of Al paste was collected in a screw tube, and 5 mL of toluene was added.
It was shaken for several tens of seconds with a handshake to disperse it, and centrifugation was performed.
The supernatant was removed, 5 mL of toluene was added again, and dispersion and centrifugation were performed in the same manner.
A small amount (about several mg) of the precipitated Al paste was collected, dispersed in 5 mL of toluene, dropped onto a 1 cm square silicon wafer, and air-dried.
((2) Acquisition of measurement image)
The measurement of the average roughness Ra on the surface of the particles was carried out under the following conditions.
Particles capable of securing a 4 μm square field of view were selected, and images for measurement were acquired under the following conditions.
Equipment: Bruker AXS Dimension Icon
Measurement mode: Tapping mode
Probe: NCH type Si single crystal probe (k = 040N / mtype)
Measuring field of view: 4 μm square / 512pixel
((3) Analysis and calculation of average roughness Ra on the surface of particles)
The analysis was performed using the analysis software attached to the device.
After performing the primary tilt correction, Ra was calculated using the roughness analysis function.
Software: Nanoscope Analysis (analysis software attached to the device)
Post-measurement correction: Primary tilt correction Roughness measurement: Ra (automatic calculation)

[(VII) Reefing value]
((1) Preparation of test paint)
The following solvents were mixed to prepare 370.0 g of the mixed solvent.
Mineral Spirit 207g
Petroleum benzine 89g
Xylene 74g
200 g of Kumaron resin (manufactured by Nippon Steel Chemical Co., Ltd .: Esclon v-120) and 370 g of the prepared mixed solvent were placed in a reagent bottle, and the reagent bottle was placed on a constant temperature water bath at 80 ° C and completely dissolved at a dissolution temperature of 40 ° C or less. .. After allowing this liquid to cool to room temperature, it was used as a test paint.
((2) Preparation of paint for measurement)
The day before the measurement, the test paint prepared in (1) above was taken into a 5 mL glass cylinder with a Komagome pipette and sealed.
2.8 g of aluminum paste containing the aluminum pigment to be measured was weighed in a 100 mL beaker.
30.7 g of the test paint was added to this beaker little by little with a Komagome pipette, stirred and mixed, and covered.
Then, it was left at room temperature of 20 degreeC for 30 minutes, and the paint for measurement was obtained.
((3) Measurement of reefing value)
The measuring paint prepared in (2) above is slowly stirred with a spatula, poured into a test cylinder to a height of 112 mm, and a steel piece attached to a cork stopper is immersed in the paint of the test cylinder for 90 seconds. The operation of rotating at an angle of ° and reversing the direction every second was continued for 10 seconds.
The steel piece was pulled up vertically in 6 seconds so as not to get wet with the wall of the test cylinder, taken out of the cylinder, and immediately placed vertically in a glass cylinder containing 5 mL of the test paint and fixed by sealing.
The cylinder was kept from vibrating, shielded from sunlight, and left for 6 minutes.
The steel piece was taken out, and the length of the mirror surface on the surface of the steel piece was measured up to the point where the mirror surface was cut off. The total immersion depth was also measured.
The measurement was performed with n = 2, and the average value of the following formula was used as the reefing value.
Reefing value = (mirror surface length (mm) / total immersion depth (mm)) x 100
The method for measuring the reefing value is based on JIS K 5906.

[(VIII) Evaluation of brightness, fineness, and gloss]
((1) Method of manufacturing metallic base paint and painted plate)
Using the aluminum pigments obtained in Examples and Comparative Examples described later, a metallic base paint was prepared with the following composition.
Aluminum pigments of Examples and Comparative Examples (heat residue 75%): 10 parts by mass Acrylic resin: 80 parts by mass (Acrydic 47-712, manufactured by Dainippon Ink Co., Ltd.)
Melamine resin: 20 parts by mass (Super Beccamin J-820, manufactured by Dainippon Ink Co., Ltd.)
Thinner: 178.5 parts by mass (solvent mixing ratio / toluene: 70% by mass, ethyl acetate: 20% by mass)
Butyl cellosolve: 10% by mass)
Using the above paint, apply 2C1B (2 coats, 1 bake) with an air spray gun (Wider77 / manufactured by Iwata Coating Machine Co., Ltd.) at an air pressure of 4 kg / cm ^{2 so} that the base coat film thickness is approximately 20 μm. Was done. The baking conditions were 140 ° C. × 30 minutes.

((2) Measurement of brightness, fineness, and gloss)
Luminance was evaluated using a variable angle colorimeter (manufactured by Suga Test Instruments Co., Ltd.).
The incident angle was set to 45 degrees, and the measurement was performed at a light receiving angle of 5 degrees (L5), which is close to the normal reflected light, excluding the light in the specular reflection region reflected on the surface of the coating film of the coating plate for evaluation.
Luminance is a parameter proportional to the intensity of specularly reflected light from the aluminum pigment, and it was judged that the larger the measured value, the higher the intensity of specularly reflected light and the better.
As an evaluation of an index showing a feeling of fineness, the value of Granines was evaluated using BYK-mac (manufactured by BYK Gardner).
In the measurement, diffused light (-15 degrees, 45 degrees, 75 degrees) was detected by a camera detector (0 degrees), and the uniformity of the bright and dark parts was displayed as a numerical value.
The obtained Granines' value was judged to indicate that the smaller the numerical value, the more precise the feeling was obtained.
The gloss was measured at a value of 60 ° gloss using a digital variable angle gloss meter UGV-50 manufactured by Suga Test Instruments Co., Ltd.

[Example 1]
A ball mill having an inner diameter of 2 m and a length of 30 cm is filled with a composition consisting of 9.5 kg of raw material atomized aluminum powder (average particle diameter: 2 μm), 45.8 kg of mineral spirit, and 300 g of stearic acid as a grinding aid. , 0.8 mm diameter zirconia balls were ground using 309 kg.
The zirconia balls contained 94% by mass or more of the main component of _{ZrO 2 and had a circularity of 95% or more.}
Grinding was performed for 80 hours at a ball mill rotation speed of 13 rpm.
After completion of grinding, the slurry in the mill was washed out with a mineral spirit, subjected to a 400-mesh vibrating sieve, and the passed slurry was filtered and concentrated with a filter to obtain a cake having a heating residue of 76% by mass.
The obtained cake was transferred into a vertical mixer, a predetermined amount of mineral spirit was added, and the mixture was mixed for 20 minutes to obtain an aluminum pigment having a heating residue of 66% by mass.
The obtained aluminum pigment was evaluated for its fineness, brightness, and gloss.
The evaluation results are shown in Table 1.

[Example 2]
The amount of stearic acid was 100 g.
For other conditions, the same operation as in Example 1 was carried out to prepare an aluminum pigment, and the same evaluation as in Example 1 was performed.

[Example 3]
The amount of stearic acid was 600 g.
For other conditions, the same operation as in Example 1 was carried out to prepare an aluminum pigment, and the same evaluation as in Example 1 was performed.

[Example 4]
Using the raw material atomized aluminum powder (average particle size of 2.2 μm), the ball mill rotation speed was 11 rpm, and grinding was performed for 150 hours.
For other conditions, the same operation as in Example 1 was carried out to prepare an aluminum pigment, and the same evaluation as in Example 1 was performed.

[Example 5]
Grinding was carried out for 105 hours using 8.6 kg of raw atomized aluminum powder (average particle size 1.7 μm) and 515 g of stearic acid.
Further, after the completion of grinding, a cake having a residual heat of 74% by mass was obtained.
For other conditions, the same operation as in Example 1 was carried out to prepare an aluminum pigment, and the same evaluation as in Example 1 was performed.

[Example 6]
Grinding was performed using 309 kg of glass balls having a diameter of 1.3 mm.
The same formulation as in Example 4 was filled, and grinding was performed at a ball mill rotation speed of 11 rpm for 120 hours.
For other conditions, the same operation as in Example 1 was carried out to prepare an aluminum pigment, and the same evaluation as in Example 1 was performed.

[Comparative Example 1]
570 g of oleic acid was used as a grinding aid.
For other conditions, the same operation as in Example 1 was carried out to prepare an aluminum pigment, and the same evaluation as in Example 1 was performed.

[Comparative Example 2]
30 g of stearic acid was used as a grinding aid.
For other conditions, the same operation as in Example 1 was carried out to prepare an aluminum pigment, and the same evaluation as in Example 1 was performed.

[Comparative Example 3]
300 g of caprylic acid was used as a grinding aid.
For other conditions, the same operation as in Example 1 was carried out to prepare an aluminum pigment, and the same evaluation as in Example 1 was performed.

[Comparative Example 4]
The same formulation as in Example 1 was filled, and grinding was performed at a ball mill rotation speed of 24 rpm for 55 hours.
For other conditions, the same operation as in Example 1 was carried out to prepare an aluminum pigment, and the same evaluation as in Example 1 was performed.

[Comparative Example 5]
Using the same raw material atomized aluminum powder as in Example 4, and filling with the same amount as in Example 4, using 82.0 kg of mineral spirit, 950 g of stearic acid, and 309 kg of zirconia balls having a diameter of 2.0 mm, 17 rpm. Was ground for 40 hours.
Further, after the completion of grinding, a cake having a residual heat of 78% by mass was obtained.
For other conditions, the same operation as in Example 1 was carried out to prepare an aluminum pigment, and the same evaluation as in Example 1 was performed.

The leaving aluminum pigment of the present invention was excellent in all evaluations of fineness, brightness, and gloss, and it was found that the coating film exhibited an excellent chromium-like design.

The leaving aluminum pigment of the present invention is used in industrial product fields where a high-class feeling is required, for example, automobiles, information appliances, cosmetic containers, lamp reflector fields where high reflectance is required, and high-grade printing inks such as offset printing and screen printing. Has industrial potential in the field.

Claims (11)

A leafing aluminum pigment comprising particles child is ground product of ball diameter 0.6Emufai～2.4Emufai,
The average particle diameter d50 of the particles is 4 μm to 15 μm, and
Of the 100 particles obtained by the FE-SEM image, which are particles having an average particle diameter d50 ± 50% or less, the length of connecting both tips of the particle cross section with a straight line is defined as the shortest length, and both tips are defined as the shortest length. When the length of the line connected along the cross section of the particle is taken as the cross-sectional length of the particle, the flat particle having a planarity (shortest length / cross-sectional length of the particle) of 0.95 to 1.00 is defined as 100. 60% of the particles
It is contained in a number ratio of ~ 100%,
A reefing aluminum pigment having a reefing value of 82 or more according to JIS K 5906. The reefing aluminum pigment according to claim 1, wherein the average thickness t of the particles is 0.03 μm to 0.12 μm. The ratio (d50 / t) of the average particle diameter d50 (μm) to the average thickness t (μm) of the particles.
The reefing aluminum pigment according to claim 1 or 2, wherein is 90 to 250. The reefing aluminum pigment according to any one of claims 1 to 3, wherein the surface roughness Ra of the particles is 2 to 12 nm. The reefing aluminum pigment according to any one of claims 1 to 4, wherein the reefing value is 86 or more. The method for producing a reefing aluminum pigment according to any one of claims 1 to 5.
A method for producing a reefing aluminum pigment, which comprises a step of grinding atomized aluminum powder with a grinding device equipped with a ball mill having a diameter of 0.6 mφ to 2.4 mφ. A coating composition containing the reefing aluminum pigment according to any one of claims 1 to 5. A coating film containing the coating composition according to claim 7. The article having the coating film according to claim 8. An ink composition containing the reefing aluminum pigment according to any one of claims 1 to 5. A printed matter containing the ink composition according to claim 10.

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