CN117957286A - Aluminum pigment, method for producing aluminum pigment, coating composition containing aluminum pigment, and ink composition - Google Patents
Aluminum pigment, method for producing aluminum pigment, coating composition containing aluminum pigment, and ink composition Download PDFInfo
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- CN117957286A CN117957286A CN202280059995.1A CN202280059995A CN117957286A CN 117957286 A CN117957286 A CN 117957286A CN 202280059995 A CN202280059995 A CN 202280059995A CN 117957286 A CN117957286 A CN 117957286A
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- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims abstract description 276
- 229910052782 aluminium Inorganic materials 0.000 title claims abstract description 223
- 239000000049 pigment Substances 0.000 title claims abstract description 174
- 239000000203 mixture Substances 0.000 title claims description 24
- 238000004519 manufacturing process Methods 0.000 title claims description 19
- 239000008199 coating composition Substances 0.000 title claims description 13
- 239000002245 particle Substances 0.000 claims abstract description 300
- 238000000227 grinding Methods 0.000 claims description 106
- 229910052751 metal Inorganic materials 0.000 claims description 58
- 239000002184 metal Substances 0.000 claims description 58
- 238000000034 method Methods 0.000 claims description 30
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- 238000013461 design Methods 0.000 abstract description 16
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- REYJJPSVUYRZGE-UHFFFAOYSA-N Octadecylamine Chemical compound CCCCCCCCCCCCCCCCCCN REYJJPSVUYRZGE-UHFFFAOYSA-N 0.000 description 3
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- ALSTYHKOOCGGFT-KTKRTIGZSA-N (9Z)-octadecen-1-ol Chemical compound CCCCCCCC\C=C/CCCCCCCCO ALSTYHKOOCGGFT-KTKRTIGZSA-N 0.000 description 1
- 229920002799 BoPET Polymers 0.000 description 1
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- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
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- 229920000122 acrylonitrile butadiene styrene Polymers 0.000 description 1
- 238000007605 air drying Methods 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- CEGOLXSVJUTHNZ-UHFFFAOYSA-K aluminium tristearate Chemical compound [Al+3].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O CEGOLXSVJUTHNZ-UHFFFAOYSA-K 0.000 description 1
- 229940063655 aluminum stearate Drugs 0.000 description 1
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- MAQCMFOLVVSLLK-UHFFFAOYSA-N methyl 4-(bromomethyl)pyridine-2-carboxylate Chemical compound COC(=O)C1=CC(CBr)=CC=N1 MAQCMFOLVVSLLK-UHFFFAOYSA-N 0.000 description 1
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- GOQYKNQRPGWPLP-UHFFFAOYSA-N n-heptadecyl alcohol Natural products CCCCCCCCCCCCCCCCCO GOQYKNQRPGWPLP-UHFFFAOYSA-N 0.000 description 1
- LYRFLYHAGKPMFH-UHFFFAOYSA-N octadecanamide Chemical compound CCCCCCCCCCCCCCCCCC(N)=O LYRFLYHAGKPMFH-UHFFFAOYSA-N 0.000 description 1
- FATBGEAMYMYZAF-KTKRTIGZSA-N oleamide Chemical compound CCCCCCCC\C=C/CCCCCCCC(N)=O FATBGEAMYMYZAF-KTKRTIGZSA-N 0.000 description 1
- 229940055577 oleyl alcohol Drugs 0.000 description 1
- XMLQWXUVTXCDDL-UHFFFAOYSA-N oleyl alcohol Natural products CCCCCCC=CCCCCCCCCCCO XMLQWXUVTXCDDL-UHFFFAOYSA-N 0.000 description 1
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Landscapes
- Pigments, Carbon Blacks, Or Wood Stains (AREA)
Abstract
Provided is an aluminum pigment which has excellent densification, optical properties and dispersibility/workability and can realize a metallic design. An aluminum pigment, wherein the average thickness of metallic aluminum particles is 0.02 to 0.20 [ mu ] m, the average aspect ratio (particle cross-sectional length/particle cross-sectional thickness) is 40 to 100, and the standard deviation of the aspect ratio is 15 to 70.
Description
Technical Field
The present invention relates to an aluminum pigment, a method for producing the same, a coating composition containing the aluminum pigment, and an ink composition.
Background
Conventionally, aluminum pigments have been widely used in various fields as pigments having both a unique metallic feel that other pigments do not have and an excellent hiding power for a substrate.
In recent years, in automotive body coating, automotive interior parts coating, optical instrument metal coating, and the like, an appearance having a denser and higher-quality feel with high brightness, lightness, and high glossiness is being emphasized, and from the viewpoint of exhibiting the original functions and equivalent or higher value of the product, it is expected that these will be further emphasized in the future.
As a method for achieving the above-described excellent appearance characteristics, there is exemplified atomization of particles of an aluminum pigment. It is known that the micronization of the aluminum pigment particles is effective for improving the dense feel.
However, if the particles of the aluminum pigment are micronized, there are problems such as a decrease in the orientation of the particles in the coating film, a decrease in brightness, and an increase in the generation of scattered light.
On the other hand, if the particle diameter of the aluminum pigment is increased, there is a problem that the particle feel as the particle penetration destination in the coating film is remarkable.
In order to solve the above problems, there is a method of thinning aluminum particles.
For example, patent document 1 discloses an aluminum pigment which can realize a plating-like appearance by reducing the grinding time of a raw aluminum powder to a thin film and thus has excellent metallic luster.
Patent documents 2 and 3 disclose that the prescribed thin film aluminum pigment improves the workability such as dispersibility by specifying the thickness distribution (the range of the relative width Δh) and the aspect ratio of aluminum particles.
Patent document 4 discloses a method for producing an aluminum pigment by a metal vapor deposition method, in which an aluminum pigment having a thin aluminum particle film thickness and being extremely excellent in single thickness and smoothness is produced by a method completely different from a method for producing an aluminum pigment by mechanical processing using a pulverizer, and a dense feel, high brightness, and high gloss can be obtained.
Further, patent document 5 proposes a method of reducing the amount of fine particle components and the amount of particles having a predetermined particle size of 1 μm or less in the whole aluminum pigment, whereby a high metallic feel can be achieved.
Patent document 6 proposes a method of achieving a mirror-like metal design by improving the flatness of particles.
Prior art literature
Patent literature
Patent document 1: japanese patent laid-open publication No. 2003-82258
Patent document 2: japanese patent laid-open No. 2014-159583
Patent document 3: WO 2004/087816
Patent document 4: japanese patent laid-open No. 2002-528639
Patent document 5: international publication No. 2019/077904 booklet
Patent document 6: international publication No. 2017/030077 booklet
Disclosure of Invention
Problems to be solved by the invention
In addition to the conventional metal-like design which requires high brightness and high gloss, there is an increasing demand for metal-like design which has a dense feel and which is extremely bright in a high-gloss region close to regular reflection, as a result of observing the tendency of design in automotive body coating, automotive interior part coating, and metal coating for optical instruments. However, in the future, most of the aluminum pigments have a curved shape and curved surface design, and the dark portion increases depending on the angle of observation due to the optical anisotropy that is a characteristic of the aluminum pigment, and there is a problem that the characteristics of brightness, gloss, and dense feel cannot be exhibited. Therefore, there is an increasing demand for a metal design which maintains a high brightness in a specular reflection-close highlight region and has a high brightness even in a wide reflection region, that is, which has a small color change due to an angle of observation and a small angle dependency.
Further, aluminum pigments have been increasingly micronized and thinned as they have been formed into high-quality designs in recent years, and therefore, dispersibility tends to be poor in the case of paint formation, and not only appearance design properties but also workability are poor, so that there is an increasing demand for dispersibility.
In addition, in the field of advanced printing inks such as gravure printing, offset printing, screen printing, and the like, there is an increasing demand for equivalent metallic design and dispersibility.
However, the aluminum pigments described in patent documents 1 to 3 have a problem that they have not yet obtained sufficient characteristics from the viewpoints of a high dense feel, a high brightness in a high-brightness region, a high brightness in a wide reflection region, and further, ease of dispersion and a high gloss feel, by extending aluminum particles to a thin thickness, thereby obtaining excellent metallic gloss.
Further, although the aluminum pigment described in patent document 4 has a high dense feel and a high brightness by being produced by the vapor deposition method, there is a problem that the dispersibility tends to be poor due to the influence of a release agent or the like in the production process, and therefore, similar to the above, the characteristics still remain insufficient from the viewpoints of the high dense feel, the high brightness in the high-brightness region, the high brightness in the wide reflection region, further, the ease of dispersibility, and the high glossiness.
In addition, although the aluminum pigment described in patent document 5 has a problem in that the brightness is increased by reducing the amount of the fine particle component and the amount of particles having a predetermined particle size of 1 μm or less in the entire aluminum pigment, the aluminum pigment has no consideration of the granular feel of aluminum, and in that the aluminum pigment has a high densification feel, a high brightness in a high brightness region, a high brightness in a wide reflection region, and further, a high glossiness, all of which are realized, and still has insufficient characteristics.
In addition, although the aluminum pigment described in patent document 6 can realize a mirror-like metallic design by improving the flatness of the particles, there is a problem that sufficient characteristics are not obtained from the viewpoint of high densification and high glossiness.
As described above, the conventional techniques have a problem that aluminum pigments which are not capable of achieving high dense feel, high brightness in a high-brightness region, high brightness in a wide reflection region, easy dispersibility, and high glossiness are all obtained.
Accordingly, in view of the above-described problems of the prior art, an object of the present invention is to provide an aluminum pigment (composition) which has a high dense feel, a high brightness in a high-gloss region, and a high brightness in a wide reflection region, is further easily dispersible, has a high glossiness, is excellent in all satisfactory optical characteristics and dispersibility and workability, and can realize a metallic design.
Solution for solving the problem
The present inventors have conducted intensive studies on the problems of the prior art described above, and as a result, have found that an aluminum pigment which is excellent in metal appearance design, dispersion/workability, and glossiness, and which is capable of exhibiting a high degree of brightness in a specular reflection-close high light region, and a high brightness even in a wide reflection region, that is, a small change in color due to an observation angle, and a small angle dependency, is obtained by focusing on the cross-sectional shape and the fine particle content of metal aluminum particles in an aluminum pigment, and by limiting the amount of fine particles contained in the aluminum pigment and the flatness of the particles in addition to the thickness and the length-thickness ratio of the metal aluminum particles in the coating film cross-section being within specific ranges.
Namely, the present invention is as follows.
[1]
An aluminum pigment, wherein the average thickness of metallic aluminum particles is 0.02 to 0.20 [ mu ] m, the average aspect ratio (particle cross-sectional length/particle cross-sectional thickness) is 40 to 100, and the standard deviation of the aspect ratio is 15 to 70.
[2]
The aluminum pigment according to [1], wherein the ratio of the number of particles having a length to thickness ratio of 20 or less to the whole is 30% or less.
[3]
The aluminum pigment according to [1] or [2], wherein the ratio of the number of particles having a length to thickness ratio of 110 or more to the whole is 30% or less.
[4]
The aluminum pigment according to any one of [1] to [3], wherein an arithmetic average height Sa of the surface roughness of the particles is 2 to 15nm.
[5]
The aluminum pigment according to any one of [1] to [4], wherein the average thickness of the particles is 0.03 to 0.15. Mu.m.
[6]
The aluminum pigment according to any one of [1] to [5], wherein the average aspect ratio of the particles is 40 to 90.
[7]
The aluminum pigment according to any one of [1] to [6], wherein the aluminum pigment contains metal aluminum particles having a particle diameter of 0.2 to 2.0 μm and a number ratio of 15 to 70% of the total metal aluminum particles.
[8]
The aluminum pigment according to any one of [1] to [7], wherein the aluminum pigment contains at least 60% by number of the above-mentioned particles as planar particles having a planarity (shortest length/particle cross-sectional length) of 0.95 to 1.00.
[9]
A method for producing an aluminum pigment according to any one of [1] to [8], comprising: a step of grinding the raw material metal aluminum powder by a grinding device, and a step of classifying the ground slurry.
[10]
The method for producing an aluminum pigment according to [9], wherein the step of grinding is performed in 2 stages.
[11]
A coating composition comprising the aluminum pigment according to any one of [1] to [8 ].
[12]
An ink composition comprising the aluminum pigment according to any one of [1] to [8 ].
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, it is possible to provide an aluminum pigment (composition) which can obtain a high dense feel, a high brightness in a high light region close to regular reflection, and a metallic design which exhibits a high brightness even in a wide reflection region, and which can realize good dispersibility and workability and a high glossiness.
Drawings
FIG. 1 is a photograph showing an example of an FE-SEM image of a particle cross section of an aluminum pigment obtained by using a FE-SEM (HITACHI system/S-4700) of field emission type for explaining a method of evaluating a particle cross section thickness and a length-thickness ratio of metal aluminum particles in an aluminum pigment. The white, laterally elongated objects in the photograph correspond to metallic aluminum particles. In fig. 1, the white portion corresponds to the area of the cross section of the metal aluminum particle, the lateral direction corresponds to the length of the cross section of the particle, and the vertical direction corresponds to the thickness of the cross section of the particle.
FIG. 2 is a photograph showing an example of an observation image of the particle surface of an aluminum pigment obtained by using a microscope (HIROX CO., LTD. Co., ltd./KH-3000) for explaining a method of evaluating the particle number ratio of metal aluminum particles having a particle diameter of 0.2 to 2.0. Mu.m in the aluminum pigment. The white round and irregular objects in the photograph correspond to the metallic aluminum particles. In fig. 2, the white portion mainly corresponds to the particle shape as viewed from a plane perpendicular to the thickness direction of the metal aluminum particles.
FIG. 3 is a photograph showing an example of an FE-SEM image of a particle cross section of an aluminum pigment obtained by using a FE-SEM (HITACHI system/S-4700) for explaining a method of evaluating the flatness of particles of an aluminum pigment.
Detailed Description
The mode 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 the present invention is not limited to the following. The present invention can be implemented by appropriately modifying the scope of the gist thereof.
[ Aluminum pigment ]
The aluminum pigment of the present embodiment has an average thickness t of metal aluminum particles, as measured from a cross-sectional view, of 0.02 to 0.20 μm, an average aspect ratio (particle cross-sectional length/particle cross-sectional thickness) of 40 to 100, and a standard deviation of the aspect ratio of 15 to 70.
The metallic aluminum particles contained in the aluminum pigment of the present invention preferably have a thin film-like, scaly or flaky shape with a small thickness and a flat shape, and the particle diameter is a measured value in a plane perpendicular to the thickness direction, and the average thickness-to-average aspect ratio (particle cross-sectional length/particle cross-sectional thickness) is a measured value in the particle cross section.
In the aluminum pigment of the present embodiment, the average thickness, length-to-thickness ratio (particle cross-sectional length/particle cross-sectional thickness), particle number ratio (%) of particle diameter 0.2 to 2.0 μm, arithmetic average height Sa (nm) of surface roughness, and planar particle ratio (%) of the metal aluminum particles are defined as follows.
The average thickness t and the aspect ratio (particle cross-sectional length/particle cross-sectional thickness) of the metal aluminum particles can be obtained by obtaining an FE-SEM image of the cross-section of a coating film formed using the coating composition containing the aluminum pigment of the present embodiment and measuring the obtained image by image analysis software.
In the FE-SEM image of the cross section of the coating film, the outline, measurement area, and length in the long axis direction of the metal aluminum particles were extracted along the shape using image analysis software. The area/length of the extracted particle cross section was determined, and the calculated value was set as "particle cross section thickness".
The ratio of the cross-sectional length of the particles to the cross-sectional thickness of the particles (particle cross-sectional length/particle cross-sectional thickness) was determined, and the calculated value was defined as the "aspect ratio" of the particles.
The length-thickness ratio of 100 or more particles was determined by the definition described above, and the average value and standard deviation were determined. Similarly, from the image analysis result, the number ratio of particles having a length to thickness ratio of 20 or less to the whole and the number ratio of particles having a length to thickness ratio of 110 or more to the whole can be obtained.
The production of a coating film cross section, the acquisition of an FE-SEM image, and the image analysis can be performed by the methods described in examples described later.
The aluminum pigment of the present embodiment has an average thickness of 0.02 to 0.20 μm, an average aspect ratio (particle cross-sectional length/particle cross-sectional thickness) of 40 to 100, and a standard deviation of 15 to 70 in the aspect ratio, which are obtained by the above cross-sectional observation, and thus can maintain a dense feel, improve brightness and brightness, and obtain a preferable design.
The cross-sectional thickness t (μm) of the metal aluminum particles can be obtained by using an FE-SEM image of a cross-section of the coating film suitable for the measurement of the aspect ratio of the particles and by measuring the cross-section using image analysis software.
Specifically, in the FE-SEM image of the coating film cross section, the outline of the particles was extracted along the shape using image analysis software, and the area/size (length) of the extracted particle cross section was obtained, and the calculated value was defined as "particle cross section thickness". The average thickness t (μm) of the metallic aluminum particles can be obtained by calculating an arithmetic average of 100 or more thicknesses of the randomly selected particles.
The average thickness t (μm) of the metallic aluminum particles in the aluminum pigment of the present embodiment is 0.02 μm to 0.20 μm.
When the average thickness t is 0.02 μm or more, deformation and cracking of the particles can be suppressed, and the surface smoothness can be maintained, so that high brightness can be obtained. In addition, the dispersibility and workability in the painting process are good.
The average thickness t of the particles is 0.20 μm or less, whereby the shadow area at the end of the particles can be suitably adjusted, and a dense feel and a high glossiness can be obtained.
The average thickness t (μm) of the metallic aluminum particles in the aluminum pigment of the present embodiment is preferably 0.03 μm or more and 0.18 μm or less, more preferably 0.03 μm or more and 0.15 μm or less, still more preferably 0.04 μm or more and 0.16 μm or less, 0.04 μm or more and 0.14 μm or less, still more preferably 0.05 μm or more and 0.13 μm or less.
The average length to thickness ratio of the metal aluminum particles in the aluminum pigment of the present embodiment is 40 to 100.
When the average aspect ratio is 40 or more, a dense and smooth coating film can be obtained when the coating composition is used for coating, with high brightness, high brightness in a wide area, and higher hiding power.
By having an average aspect ratio of 100 or less, warpage, deformation, and cracking of the particles can be suppressed.
The average length to thickness ratio of the metal aluminum particles in the aluminum pigment of the present embodiment is preferably 40 to 90 or 45 to 95, more preferably 45 to 85, still more preferably 50 to 90, still more preferably 50 to 80.
The standard deviation of the aspect ratio is 15 to 70. When the standard deviation of the long-to-thick ratio is 15 or more, a high brightness can be maintained for a wide reflection region, and a light-dark difference due to an angle can be suppressed. By having a standard deviation of 70 or less, high brightness and high glossiness of the specular reflection area can be maintained.
The standard deviation of the aspect ratio of the aluminum pigment according to the present embodiment is preferably 20 to 65.
The aluminum pigment according to the present embodiment preferably has a ratio of the number of particles having a length to thickness ratio of 20 or less of 30% or less of the whole.
The number ratio of particles having a length-thickness ratio of 20 or less is preferably 30% or less based on the whole, since a metallic coating film having a metallic feel with higher brightness can be obtained.
The aluminum pigment according to the present embodiment preferably has a ratio of the number of particles having a length to thickness ratio of 20 or less, more preferably 20% or less based on the whole.
The ratio of the number of particles having a length to thickness ratio of 110 or more is preferably 30% or less based on the whole of the metal aluminum particles in the aluminum pigment of the present embodiment.
The number ratio of particles having a length-thickness ratio of 110 or more to the whole is 30% or less, whereby warping, deformation and cracking of the particles can be suppressed. And is therefore preferred. Further, dispersibility and workability at the time of painting become better, so that it is preferable.
The aluminum pigment according to the present embodiment preferably has a ratio of the number of particles having a length to thickness ratio of 110 or more, more preferably 20% or less based on the whole.
The arithmetic average height Sa of the surface roughness (irregularities on the particle surface) of the metallic aluminum particles in the aluminum pigment of the present embodiment is an index indicating the smoothness of the surface of the particles of the aluminum pigment, and can be measured by a scanning probe microscope (SPM, scanning Probe Microscope) including an atomic force microscope or the like.
The arithmetic mean height Sa is preferably 2 to 15nm.
Since the arithmetic average height Sa is 15nm or less, the smoothness of the particle surface is high, and the amount of specular reflection of light is increased, and a higher brightness feeling is obtained. By setting the arithmetic average height Sa to 2nm or more, the grinding time required for producing the aluminum pigment of the present embodiment is not extremely prolonged, and the productivity is excellent.
The arithmetic mean height Sa is more preferably 2 to 12nm.
The flatness (shortest length/particle cross-sectional length) of the metallic aluminum particles in the aluminum pigment of the present embodiment can be obtained by obtaining an FE-SEM image of the cross-section of the coating film described above and measuring the image by 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 obtained by connecting the two ends of the cross section of the particle in a straight line was taken as the "shortest length". The measured value of a line formed by connecting both ends of the particle cross section along the shape of the particle cross section is referred to as the "particle cross section length".
The value of the ratio of the shortest length to the cross-sectional length of the particle (shortest length/cross-sectional length of the particle) is defined as the planarity of the particle.
The closer the planarity of the particles is to 1.00, the less warpage and deformation of the particles are indicated.
The planarity of 100 particles was determined by the definition above.
The degree of flatness of the particles was set to 0.95, and particles in the range of 0.95 to 1.00 were defined as planar particles, and the ratio was determined as a planar particle ratio (%) to the number ratio.
The proportion of particles having a flatness in the range of 0.95 to 1.00 is preferably 60% or more, since the brightness of the specular reflection region can be maintained high. More preferably from 60% to 98%.
As a method for achieving more excellent glossiness in the aluminum pigment according to the present embodiment, it is preferable to set metal aluminum particles having a particle diameter of 0.2 to 2.0 μm to a specific ratio. The enlargement of the particle diameter of the aluminum pigment is effective for improving the metallic luster. On the other hand, if the particles of the aluminum pigment are excessively large, the feeling of particles in the coating film is remarkable, and therefore the number ratio of particles of a specific particle diameter is preferably controlled within a certain range.
Specifically, the particle number ratio of the metal aluminum particles in the aluminum pigment according to the present embodiment is preferably 15 to 70% based on the total particle number obtained from the photograph of the observation image of the particle surface of the aluminum pigment obtained by using a microscope, the particle size of the metal aluminum particles being 0.2 to 2.0 μm. The particle size ratio of 0.2 to 2.0 μm suppresses the feeling of particles and achieves high glossiness.
The particle number ratio of the metal aluminum particles in the aluminum pigment of the present embodiment is more preferably 20 to 65% and the particle diameter of the metal aluminum particles is 0.2 to 2.0 μm.
The above-described preferable range of the particle number ratio of the metal aluminum particles having a particle diameter of 0.2 to 2.0 μm can be achieved by performing the step of grinding the raw material metal aluminum powder in2 stages in the method for producing an aluminum pigment described later, and the effect that the obtained aluminum pigment has a high glossiness can be exhibited.
[ Method for producing aluminum pigment ]
The method for producing the aluminum pigment according to the present embodiment will be described below.
The method for producing an aluminum pigment according to the present embodiment comprises: a step of grinding raw material metal aluminum powder (atomized aluminum powder) by a grinding device equipped with a ball mill or the like; and classifying the milled slurry. The grinding step preferably includes: a step 1 of smoothing and uniformly thinning aluminum particles; and a2 nd stage grinding step of adjusting the amount of fine aluminum particles as needed (i.e., a step of grinding the aluminum particles in 2 stages).
The average thickness, aspect ratio (particle cross-sectional length/particle cross-sectional thickness) and particle number ratio of 0.2 to 2.0 μm can be adjusted by appropriately adjusting and combining the conditions such as the particle diameter of the atomized aluminum powder to be used as the raw material, the mass of each 1 of the grinding balls to be used, the rotation speed of the grinding device, the grinding solvent, the grinding aid, and the like.
< Procedure of grinding >
Considering that the average particle thickness is in the range of 0.02 to 0.20 μm, the following conditions are combined for particularly preferred milling conditions: as the raw material, atomized aluminum powder having a particle size of preferably 1.0 to 6.0 μm, more preferably 1.5 to 5.0 μm is used, the mass of each 1 grinding ball used in the grinding apparatus is preferably 0.08 to 11.00mg, more preferably 0.08 to 9.00mg, and the rotation speed of the grinding apparatus is 33 to 78%, more preferably 36 to 57% relative to the critical rotation speed (Nc).
< Grinding ball >)
The specific gravity of the grinding balls used in the ball mill or the like is preferably 8 or less, more preferably 7.5 or less, and even more preferably 7 or less, from the viewpoint of easy adjustment of the above-mentioned particles and from the viewpoint of improvement of the surface smoothness of the aluminum particles.
The specific gravity of the milled balls is preferably greater than the specific gravity of the milled solvent. Since the specific gravity of the grinding balls is larger than that of the grinding solvent, the grinding balls can be prevented from floating in the solvent, and the shearing stress between the grinding balls can be sufficiently obtained, and the grinding tends to be sufficiently performed.
The grinding balls used in the method for producing an aluminum pigment according to the present embodiment are preferably grinding balls having high surface smoothness such as stainless steel balls, zirconia balls, and glass balls, from the viewpoints of adjustment of surface smoothness of aluminum particles and durability of the grinding balls.
On the other hand, steel balls, alumina balls, and the like having low surface smoothness are not preferable from the viewpoints of adjustment of surface smoothness of aluminum particles and durability of the grinding balls.
Therefore, for example, in the case of stainless steel balls, it is preferable to use stainless steel balls whose surface smoothness is improved by mechanical polishing and chemical polishing.
The mass of each grinding ball is preferably 0.08 to 11.00mg as described above.
By using the grinding balls having a mass of 0.08 mg/or more, the grinding balls do not move individually but move in clusters or blocks, and therefore, the occurrence of a phenomenon in which shearing stress between the grinding balls is reduced without grinding, so-called group motion (group motion), can be prevented.
Further, by using the grinding balls having a mass of 11.00 mg/or less, excessive impact force applied to the aluminum powder can be prevented, and generation of warpage, deformation, cracks, and the like can be prevented.
In addition, instead of the ball mill, a medium stirring mill may be used in the same manner as described above. As the medium stirring mill, for example, a screw type (tower type), a stirring tank type, a flow pipe type, an annular (annular) type, or the like medium stirring mill can be used.
< Raw Material Metal aluminum powder >)
The atomized aluminum powder (raw material metal aluminum powder) as the raw material is preferably low in impurities other than aluminum.
The purity of the atomized aluminum powder is preferably 99.5% or more, more preferably 99.7% or more, and still more preferably 99.8% or more.
The average particle diameter of the atomized aluminum powder as the raw material is preferably 1.0 to 6.0. Mu.m, more preferably 1.5 to 5.0. Mu.m.
The atomized aluminum powder having an average particle diameter of 1.0 μm or more is preferable because the energy applied to the particles during grinding is not excessively large, warpage and deformation of the particles can be prevented, and the particle shape can be maintained well.
The atomized aluminum powder as the raw material is preferably spherical powder or teardrop powder. By using these, the shape of the aluminum pigment during grinding tends to be less likely to be lost. On the other hand, needle-like powder and amorphous powder are not preferable because the shape of the aluminum pigment during grinding tends to be lost.
< Milling solvent >
The grinding solvent is preferably used when the aluminum pigment of the present embodiment is produced by a grinding apparatus including a ball mill or the like.
The type of the milling solvent is not limited to the following, and examples thereof include conventionally used hydrocarbon solvents such as mineral spirits and solvent naphtha, and low-viscosity solvents such as alcohols, ethers, ketones and esters.
The milling conditions for the atomized aluminum powder are preferably such that the volume of the milling solvent is 1.5 to 16.0 times, more preferably 2.0 to 12.0 times, the mass of aluminum in the atomized aluminum powder. The volume of the milled solvent is preferably 1.5 times or more the mass of aluminum in the atomized aluminum powder, because warpage, deformation, cracking, and the like associated with long-term milling of the atomized aluminum powder can be prevented.
In addition, since the volume of the milling solvent is 16.0 times or less the mass of aluminum in the atomized aluminum powder, uniformity in the mill during milling is improved, and the atomized aluminum powder and the milling medium are effectively brought into contact with each other, so that milling tends to be suitably performed.
The volume of the milled sphere is preferably 0.5 to 3.5 times, more preferably 0.8 to 2.5 times, the volume of the milled solvent (volume of the milled sphere/volume of the milled solvent).
When the volume of the grinding balls is 0.5 times or more the volume of the grinding solvent, uniformity of the grinding balls in the mill during grinding is improved, and grinding tends to be suitably performed.
Further, since the ratio of the volume of the grinding balls to the volume of the grinding solvent is 3.5 times or less, the ratio of the grinding balls in the mill is preferably in a suitable range, and the lamination of balls is not excessively high, the problem of deterioration in the shape such as warpage, deformation, and cracks of particles due to grinding stress is prevented, and the decrease in brightness and the increase in scattered light can be prevented.
< Grinding aid >)
In the case of producing the aluminum pigment according to the present embodiment by a milling apparatus equipped with a ball mill, a milling aid is preferably used in addition to the above-mentioned milling solvent.
The grinding aid is not limited to the following, and examples thereof include higher aliphatic alcohols such as higher unsaturated fatty acids such as oleic acid and higher aliphatic amines such as stearylamine, stearyl alcohol and oleyl alcohol; higher fatty acid amides such as stearic acid amide and oleic acid amide; higher fatty acid metal salts such as aluminum stearate and aluminum oleate.
The grinding aid is preferably used in an amount of 0.2 to 30 mass% relative to the mass of the atomized aluminum powder.
< Ball mill >
The ball mill used for grinding the atomized aluminum powder preferably has a diameter of 0.6mφ to 2.4mφ, more preferably 0.8mφ to 2.0mφ.
By using a ball mill having a diameter of 0.6m phi or more, the lamination of the grinding balls is not excessively low, and the pressure applied to the aluminum particles during grinding is in a suitable range, so that grinding tends to be suitably performed.
Further, the use of a ball mill having a diameter of 2.4m phi or less is preferable because the stacking of the grinding balls is not excessively high, and the problems of deterioration in shape such as warpage, deformation, and cracking of the particles due to the overlapping of balls are prevented, and the decrease in brightness and the increase in scattered light can be prevented.
The rotation speed of the ball mill during grinding of the atomized aluminum powder is preferably 33% to 78%, more preferably 36% to 57%, with respect to the critical rotation speed (Nc) as described above.
The ratio of the rotation speed to the critical rotation speed is preferably 33% or more, since uniformity of movement of the aluminum slurry and balls in the ball mill is maintained.
Further, when the ratio of the rotational speed to the critical rotational speed is 78% or less, the grinding balls are prevented from being stirred up or falling down by their own weight, and the problem of shape deterioration such as warping, deformation, and cracking of the aluminum particles is prevented from being caused by the impact force applied from the grinding balls.
The aluminum pigment according to the present embodiment may be produced by a vacuum vapor deposition method in addition to the production method including the step of grinding the atomized aluminum powder.
< Procedure of classification >
After the above-described grinding step, the aluminum pigment according to the present embodiment can be subjected to classification to remove particles having a large aspect ratio and small particles. As this method, there is, for example, a liquid cyclone fractionation method. Classification can be performed by feeding the ground slurry to a two-component separation type liquid cyclone classifier, a three-component separation type liquid cyclone classifier, or the like. As the classification conditions, the classification operation can be optimized by appropriately adjusting the conditions of nozzle diameter, flow rate (L/min), operating pressure (MPa), and the like as needed.
The average value, standard deviation, and particle number ratio of 0.2 to 2.0 μm of the aspect ratio of the aluminum pigment according to the present embodiment may be within the above numerical ranges, and may be adjusted by mixing a plurality of aluminum pigments different from each other in each range so as to meet the design properties that ultimately become the object.
[ Coating composition ]
The coating composition of the present embodiment contains the aluminum pigment of the present embodiment described above.
The coating composition of the present embodiment may use mica, a coloring pigment, or the like in combination in addition to the aluminum pigment.
In addition, various additives such as various resins, antioxidants, light stabilizers, polymerization inhibitors, surfactants, and the like may be used in combination in the coating composition of the present embodiment.
The coating composition of the present embodiment can be produced by mixing an aluminum pigment with other various materials as needed.
The coating composition of the present embodiment can be used as a metallic coating.
[ Ink composition ]
The ink composition of the present embodiment contains the aluminum pigment of the present embodiment described above.
The ink composition of the present embodiment may use a predetermined coloring pigment, solvent, or the like in combination in addition to the aluminum pigment.
In addition, various additives such as various resins, antioxidants, light stabilizers, polymerization inhibitors, surfactants, and the like may be used in combination in the ink composition of the present embodiment.
The ink composition of the present embodiment can be produced by mixing an aluminum pigment and other various materials as needed, and can be used as a metallic ink.
[ Other uses ]
The aluminum pigment of the present embodiment may be kneaded with a resin or the like and used as a water-resistant binder or filler.
Examples
The present embodiment will be described in more detail with reference to examples and comparative examples.
The present embodiment is not limited in any way by the following examples.
The method for measuring various physical properties used in examples and comparative examples is as follows.
[ (I) thickness of metallic aluminum particles, aspect ratio ]
((1) Manufacturing of coated plate)
Metallic paint was prepared using the aluminum pigments obtained in examples and comparative examples described below, and the following compositions were used.
Aluminum pigment: 1g of
A diluent: 50g
(Trade name "PLa-ACE THINNER No.2726", manufactured by Wucang paint Co., ltd.)
Acrylic resin: 33g
(Trade name "PLA-ACE No.7160", manufactured by Wucang paint Co., ltd.)
The above-mentioned paint was applied to an ABS resin plate in such a manner that the thickness of the dried film was 20 μm using an air spraying apparatus, and dried for 30 minutes using an oven at 60 ℃.
(2) Preparation of a coating film in section
Using the coated plate for evaluation produced as described above, a coating film cross section was produced as follows. The coated plate for evaluation was cut into a square 1cm size using scissors.
The coated plate for evaluation, which was cut at 1cm square, was repeatedly cut into a film cross section using a large rotary microtome (manufactured by the large and opto-mechanical industries, inc./RV-240), and the aluminum-acrylic resin fine protruding from the cross section was removed.
The coating film section obtained as described above was subjected to ion milling treatment by setting the position of a shield plate so that an ion beam could be irradiated to a portion 20 μm away from the coating film section using an ion milling apparatus (japan electronics system/IB-09010 CP), and a coating film section for FE-SEM image acquisition described later was produced.
(3) Obtaining a section of the particle (FE-SEM image)
The coated film section (coated plate) obtained in the foregoing (section preparation of coated film) was adhered in parallel to an SEM sample stage, and FE-SEM (HITACHI/S-4700) of the coated film section was obtained by using a field emission type FE-SEM.
For the conditions of FE-SEM observation and acquisition, the setting of the acceleration voltage was adjusted to 10kV, the image magnification was set to 3 to 1 thousand times, and the magnification was appropriately changed according to the size of the particles, and the image was taken at the magnification at which the particles entered the field of view.
Before the (capture) FE-SEM image is obtained, an electron axis alignment process is performed, so that the boundary line between the aluminum particles and the acrylic resin in the FE-SEM image is not deformed, and the brightness and the light-dark difference are appropriately set, so that the particles can be clearly and clearly distinguished. The image quality at the time of photographing was photographed at a high resolution of 2560×1920 pixels. A clear image of the sample without cracks or flaws during ion milling cross-section processing was obtained, and then the sample was used as an image for measurement, and the image was not processed, but was made to be non-processed.
((4) Analysis (measurement of particle size in section: particle thickness, aspect ratio))
The length and area of the particles in the cross section of the aluminum particles were measured by using image analysis software Image Pro Plus version 7.0.0 (Media Cybernetics) for the FE-SEM images obtained in the steps of obtaining the cross sections (FE-SEM images) of the particles ((I) - (3)), and the thickness and aspect ratio were calculated.
The FE-SEM image obtained by measuring the length and area of the aluminum particles in the cross section is read into image analysis software, and the scale length/unit is set by performing spatial correction.
Then, the outline of the particles was accurately extracted, and 2 measurement values of the area and the size (length) were obtained. The extraction of particles was performed using a free curve AOI tool, and converted into objects (objects). And then the particle image is properly enlarged and the subject is corrected to correctly extract the contour of the particle. Further, particles exceeding the image and particles not clear are designed as the object to be measured.
The measured particle size (length) is defined as "particle cross-sectional length", and the calculated value of the ratio of the area to the size (length) (area/size (length)) is defined as "particle cross-sectional thickness". The calculated value of the ratio of the particle cross-sectional length to the particle cross-sectional thickness (particle cross-sectional length/particle cross-sectional thickness) was set as "the length-thickness ratio of the particles".
Measurement value of particle cross-sectional length=size (length)
Calculated particle cross-sectional thickness = area/size (length)
Length to thickness ratio = particle cross-sectional length/particle cross-sectional thickness
The above procedure was repeated to obtain values of the aspect ratio of 100 or more particles.
[ (II) average thickness, average aspect ratio, standard deviation of aspect ratio of metallic aluminum particles, evaluation of number ratio ]
The average value (average thickness t) of the whole particle cross-sectional thickness (area/dimension (length)) of 100 or more particles obtained by the above-described ((I) - (4)) analysis, and the average value (average length-thickness ratio) of the aspect ratio (particle cross-sectional length/particle cross-sectional thickness), the standard deviation of the aspect ratio, and the number ratio of particles having an aspect ratio of 20 or less and 110 or more to the whole were obtained.
[ (III) analysis (measurement of particle size in section: particle planarity) ]
(1) Evaluation of particle planarity
For the FE-SEM images obtained in the step of obtaining particle cross sections (FE-SEM images) of the foregoing ((I) - (3)), measurement of the flatness (shortest length/particle cross-sectional length) of the aluminum particles was carried out using image analysis software Win Roof version5.5 (MITANI CORPORATION).
An image of an example of measurement of the flatness of particles (shortest length/particle cross-sectional length) is shown in fig. 3.
The straight line tool and the curve tool of the image analysis software Win rouvision 5.5 are selected, and the measured value of the straight line connecting the two ends of the cross section of the aluminum particle is used as the shortest length, the measured value of the line connecting the two ends along the cross section of the aluminum particle is used as the particle cross section length, and the value of (shortest length/particle cross section length) is used as the planeness of the aluminum particle.
This procedure was repeated to obtain a value of flatness of 100 particles.
The aluminum particles selected for obtaining the flatness value were used as the average particle diameter: particles within + -50% of d 50.
The closer the value of the flatness of the particles is to 1.00, the smaller the degree of warpage, deformation, etc. of the particles.
((2) Average particle diameter d 50)
The average particle diameter (d 50) of the aluminum pigment was measured by a laser diffraction/scattering particle diameter distribution measuring apparatus (LA-300/horiba corporation).
As the measuring solvent, mineral spirits were used.
The measurement was performed according to the instrument instructions, and as a precaution, the aluminum pigment serving as a sample was subjected to ultrasonic dispersion for 2 minutes as a pretreatment, and then placed in a dispersion tank, and after confirming that an appropriate concentration was formed, the measurement was started.
After the measurement is completed, d50 is automatically displayed.
((3) Ratio of planar particles)
From the value of the flatness (shortest length/particle cross-sectional length) of 100 particles obtained as described above, the ratio of aluminum particles in the range of 0.95 to 1.00 was obtained with the threshold value of the flatness of the particles being set to 0.95.
The aluminum pigment according to the present embodiment has a number ratio of planar particles having a particle planarity in the range of 0.95 to 1.00 of 60% or more.
[ (IV) particle diameter of 0.2 to 2.0 μm ]
((1) Manufacturing of coated plate)
Metallic paint was prepared using the aluminum pigments obtained in examples and comparative examples described below, and the following compositions were used.
Aluminum pigment: 0.25g
A diluent: 12.75g
(KANSAI PAINT Co., ltd., "trade name ACRIC 2000GL thinner")
Acrylic resin: 97.00g
(KANSAI PAINT Co., ltd., trade name "ACRIC 2000 clear")
The thus prepared paint was then shaken for 10 minutes by a paint shaker, and the paint was applied to a masking test paper (product name "masking test paper H-100JIS quality product" manufactured by Taiyou machine Co., ltd.) by using a bar coater No.6, and dried at room temperature to obtain a coated board for evaluation.
(2) Observation image acquisition of particle surface of aluminum pigment)
For the coating film (coated plate) obtained by the aforementioned ((1) production of coated plate), an observation image of the particle surface of the aforementioned coating film was obtained using a microscope (HIROX co., ltd. System/KH-3000).
The image magnification was set at 2100 times, and 10 views were taken for each 1 sample.
(3) Analysis (particle count, size measurement)
The image obtained in the step of obtaining the observed image of the particle surface of the aluminum pigment ((IV) - (2)) was measured by using image analysis software Image Pro Plus version 7.0.0 (manufactured by Media Cybernetics), the diameters of all aluminum particles present clearly were confirmed without interruption in the image, the number of particles in the whole was 100 or more, and the ratio of the diameters of 0.2 to 2.0 μm to the number of particles in the whole was calculated. In this case, particles whose shape is not clear and whose contour is unclear are overlapped with each other, and particles which are judged to be confused are excluded from measurement.
The method of extracting particles was to extract the outline of the particles accurately by manual measurement, measure the items, and select the diameter (average) as the value of the diameter of the particles.
(4) Evaluation of particle count ratio of particle size 0.2 to 2.0 μm)
The analysis of 10 fields ((IV) - (3)) was performed for each 1 sample, and the number ratio of particles having diameters (average) of 0.2 to 2.0 μm was determined based on the total number of 100 or more aluminum particles in the 10 fields.
If the number of particles to be measured is less than 100, the number of fields of view is increased by obtaining an image again, and the number of particles to be measured is set to 100 or more.
Arithmetic mean height of surface roughness of [ (V) particles: sa ]
The arithmetic average height Sa of the surface roughness of the metallic aluminum particles in the aluminum pigment is measured by the following method.
((1) Pretreatment)
The aluminum pigments obtained in examples and comparative examples described later were subjected to a cleaning treatment because they were a mixture with mineral spirits and solvent naphtha.
100Mg of Al paste (aluminum pigment) was collected in a threaded tube, and 5mL of toluene was added.
The dispersion was carried out by shaking with hands for 10 seconds, and centrifugal separation was carried out.
Toluene 5mL was added again to the supernatant removed, 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 5mL of toluene, and then added dropwise to a 1cm square silicon wafer, followed by air-drying.
(2) Acquisition of measurement image)
The arithmetic average height Sa of the surface roughness of the particles was measured under the following conditions.
Particles capable of securing a square field of view of 4 μm were selected, and an image for measurement was obtained under the following conditions.
The device comprises: AFM5100N manufactured by HITACHI HIGH-Technologies Corporation
Measurement mode: DFM (distributed feedback model)
And (3) probe: PRC-DF40P
Measurement field: 4 μm square/512 pixels (pixels)
((3) Analysis and calculation of Sa)
The parsing is performed using parsing software attached to the device.
After the inclination correction is performed once, sa is calculated using the roughness analysis function.
Software: AFM5000II
Correction after measurement: one-time inclination correction
And (3) roughness measurement: sa (automatic calculating)
[ (VI) evaluation of sense of densification, brightness, lightness and glossiness ]
((1) Preparation of paint and coated plate)
Using the aluminum pigments obtained in examples and comparative examples described below, metallic paints were prepared according to the following compositions.
Aluminum pigment: 1.25g
Mixing a diluent: 8.75g
( Solvent mixing ratio/methyl ethyl ketone: 40 mass%, ethyl acetate: 40 mass%, isopropanol: 20 mass% )
Polyurethane resin: 4.00g
(Trade name "Sanplen IB series 1700D" manufactured by Sanyo chemical industry Co., ltd.)
The prepared coating material was then dispersed for 20 minutes at a rotation speed of 500rpm using a magnetic stirrer, and coated on a PET film using a bar coater No.6, and dried at room temperature to obtain a coated plate for evaluation.
(2) Measurement of sense of densification, brightness, lightness and glossiness)
(I) Sense of densification
As an evaluation of an index showing the sense of densification, the sense of graininess was evaluated using BYK-mac (manufactured by BYK-Gardner Co.).
For evaluation of graininess, the uniformity of the light and dark portions was numerically represented by detecting the diffused light (-15 degrees, 45 degrees, 75 degrees) with a camera detector (0 degrees).
The value of the particle size (GRAININESS) is read for the measured value of the uniformity of the bright and dark portions, and the smaller the value is, the more dense the sense is judged to be.
(Ii) Brightness and brightness
Brightness and lightness were evaluated using a colorimeter VC-2 (Suga Test Instruments co., ltd.).
The incident angle was set at 45 degrees, and the brightness was measured at a setting of 5 degrees (L5) of the light receiving angle close to the specular reflection light, except for the light in the specular reflection region reflected on the surface of the coating film. Further, brightness was measured by setting 55 degrees (L55) in which the light receiving angle was shifted by 50 degrees.
The brightness was a parameter proportional to the intensity of the specular reflection light from the aluminum pigment, and the greater the measured value, the higher the specular reflection light intensity was judged to be excellent.
The brightness can capture the change in brightness observed for each angle, and the higher the value of L for each angle, the higher the intensity of light reflected at that angle, and the greater the measured value, the higher the brightness.
(Iii) Gloss level
Gloss was evaluated using UGV-5D (Suga Test Instruments co., ltd.). When the reflectance at 60 degrees was measured from the 60-degree specular gloss, the higher the 60-degree specular reflectance was, the higher the gloss of the coating film was judged to be, the more excellent the optical properties were.
[ (VII) evaluation of dispersibility ]
(1) Preparation of evaluation sample
Using the aluminum pigments obtained in examples and comparative examples described below, samples for evaluation were prepared with the following compositions.
(I) 10g of an aluminum pigment sample was weighed into a disposable cup (500 ml).
(Ii) 100ml of xylene was added to the above (i) to form a test sample.
((2) Evaluation of the test for easy dispersibility)
The evaluation sample prepared in (1) above was tested and judged by the following method.
(I) The test specimens were dispersed by stirring at 500rpm for 1 minute using a three-in-one motor.
(Ii) The dispersion was transferred to another disposable cup, and the presence or absence of undispersed sample at the bottom of the disposable cup was confirmed.
(Iii) When an undispersed sample is present, the transferred dispersion is returned, and the measurement operations of (i) to (ii) are repeated until no undispersed sample is present.
(Iv) The time required until the sample was not dispersed was used to determine that the dispersibility was good as the time required was shorter.
Example A1
A ball mill having an inner diameter of 2m and a length of 30cm was charged with a compound containing 9.5kg of atomized aluminum powder of the raw material metal (average particle diameter: 2.1 μm), 45.8kg of mineral spirits and 570g of oleic acid, and the mixture was pulverized using 309kg of zirconia balls having a diameter of 0.8 mm.
As the zirconia balls, zirconia balls containing 94 mass% or more of ZrO 2 as a main component and having a round shape of 95% or more are used.
The rotation speed of the ball mill was set to 13rpm (the ratio of the rotation speed to the critical rotation speed was 43%), and grinding was performed for 150 hours.
After the grinding, the slurry in the mill was washed out with mineral spirits and classified using a liquid cyclone classifier. First, the slurry was fed to a two-component separation type liquid cyclone classifier by adjusting the diameter of the top nozzle to 5mm, the diameter of the bottom nozzle to 2mm, and the pressure to 0.4MPa, to obtain a slurry classified on the top side. Then, the slurry was fed to a three-component separation type liquid cyclone classifier having a top nozzle diameter of 3mm, a middle nozzle diameter of 6mm, a bottom nozzle diameter of 1.5mm and a pressure of 0.6MPa, to obtain a slurry classified on the bottom side. The slurry obtained by classification was filtered through a filter and concentrated to obtain a cake containing 76 mass% of the heated residual component.
The obtained cake was transferred to a vertical mixer, and a predetermined amount of solvent naphtha was added thereto and mixed for 20 minutes to obtain an aluminum pigment having a heated residual component of 66 mass%.
The obtained aluminum pigment was evaluated for the average thickness, average length-thickness ratio, standard deviation of length-thickness ratio, number ratio of particles having length-thickness ratio of 20 or less, number ratio of particles having length-thickness ratio of 110 or more, number ratio of planar particles, arithmetic average height Sa of surface roughness of particles, number ratio of particle diameter of 0.2 to 2.0 μm by the above (I) to (V), and the densification, brightness, dispersibility, and glossiness by the above (VI) and (VII). The evaluation results are shown in Table A1.
Example A2
The starting metal was atomized aluminum powder (average particle diameter: 2.5 μm) and pulverized using zirconia balls having a diameter of 1.3 mm.
The rotation speed of the ball mill was set to 17rpm (the ratio of the rotation speed to the critical rotation speed was 57%), and grinding was performed for 50 hours.
The same operation as in [ example A1] was performed under other conditions to obtain an aluminum pigment having a heating residue of 70% by mass.
The obtained aluminum pigment was evaluated for densification, brightness, lightness, dispersibility, and glossiness by the above-mentioned (VI) and (VII). The evaluation results are shown in Table A1.
Example A3
The aluminum pigment obtained in the following (1) and (2) was mixed at a ratio of 1:1 to obtain an aluminum pigment.
(1) The raw material metal atomized aluminum powder (average particle diameter: 1.9 μm) was charged with a compound containing 53.4kg of mineral spirits and 950g of oleic acid, and pulverized with 309kg of zirconia balls having a diameter of 1.7 mm.
The rotation speed of the mill was set to 13rpm (the ratio of the rotation speed to the critical rotation speed was 43%), and grinding was performed for 80 hours.
The same operation as in [ example A1] was performed under the other conditions to obtain an aluminum pigment having a heating residue of 68% by mass.
(2)
The same procedure as in (1) above was carried out using the raw material metal atomized aluminum powder (average particle diameter: 2.8 μm) under the other conditions to obtain an aluminum pigment having a heat-treated residual component of 70 mass%.
(3)
The obtained aluminum pigment was evaluated for densification, brightness, lightness, dispersibility, and glossiness by the above-mentioned (VI) and (VII). The evaluation results are shown in Table A1.
Example A4
The rotation speed of the ball mill was set at 17rpm (the ratio of rotation speed/critical rotation speed was 57%).
The other conditions were the same as in [ example A1 ].
The obtained aluminum pigment was evaluated for densification, brightness, lightness, dispersibility, and glossiness by the above-mentioned (VI) and (VII). The evaluation results are shown in Table A1.
Comparative example A1
The grinding was carried out by the same compound as in the foregoing [ example A1 ].
After the completion of grinding, the slurry in the mill was refined with mineral oil, coarse particles were removed by a 400-mesh vibrating screen, and the mixture was filtered and concentrated by a filter to obtain a cake containing 74% by mass of the heated residual component (classification step was not performed).
The obtained cake was transferred to a vertical mixer, and a predetermined amount of solvent naphtha was added thereto and mixed for 20 minutes to obtain an aluminum pigment having a heated residual component of 64 mass%.
The obtained aluminum pigment was evaluated for densification, brightness, lightness, dispersibility, and glossiness by the above-mentioned (VI) and (VII). The evaluation results are shown in Table A1.
Comparative example A2
The material filled with the same compound as in the foregoing [ example A1] was used, and the milling was performed by changing the rotation speed of the ball mill to 25rpm (the ratio of the rotation speed to the critical rotation speed was 83%).
After the completion of grinding, the slurry in the mill was refined with mineral oil, coarse particles were removed by a 400-mesh vibrating screen, and the mixture was filtered and concentrated by a filter to obtain a cake containing 72% by mass of the heated residual component (classification step was not performed).
The obtained cake was transferred to a vertical mixer, and a predetermined amount of solvent naphtha was added thereto and mixed for 20 minutes to obtain an aluminum pigment having a heating residue content of 62 mass%.
The obtained aluminum pigment was evaluated for densification, brightness, lightness, dispersibility, and glossiness by the above-mentioned (VI) and (VII). The evaluation results are shown in Table A1.
Comparative example A3
The grinding was carried out using a raw material metal atomized aluminum powder (average particle diameter: 6.5 μm). The other compounds and grinding conditions were subjected to the same procedure as in [ example A1 ].
After the completion of grinding, the slurry in the mill was refined with mineral oil, coarse particles were removed by a 400-mesh vibrating screen, and the mixture was filtered and concentrated by a filter to obtain a cake containing 76 mass% of the heated residual component (classification step was not performed).
The obtained cake was transferred to a vertical mixer, and a predetermined amount of solvent naphtha was added thereto and mixed for 20 minutes to obtain an aluminum pigment having a heated residual component of 66 mass%.
The obtained aluminum pigment was evaluated for densification, brightness, lightness, dispersibility, and glossiness by the above-mentioned (VI) and (VII). The evaluation results are shown in Table A1.
Comparative example A4
The grinding was carried out using a raw material metal atomized aluminum powder (average particle diameter: 2.2 μm).
The rotation speed of the ball mill was set to 11rpm (the ratio of the rotation speed to the critical rotation speed was 37%), and grinding was performed for 110 hours.
The other compounds and grinding conditions were subjected to the same procedure as in [ example A1 ].
After the completion of grinding, the slurry in the mill was refined with mineral oil, coarse particles were removed by a 400-mesh vibrating screen, and the mixture was filtered and concentrated by a filter to obtain a cake containing 78% by mass of the heated residual component (classification step was not performed).
The obtained cake was transferred to a vertical mixer, and a predetermined amount of solvent naphtha was added thereto and mixed for 20 minutes to obtain an aluminum pigment having a heating residue content of 68 mass%.
The obtained aluminum pigment was evaluated for densification, brightness, lightness, dispersibility, and glossiness by the above-mentioned (VI) and (VII). The evaluation results are shown in Table A1.
[ Table A1]
Table A @
As is clear from Table A1, the aluminum pigment of the present invention was dense, and had extremely high brightness and brightness, and also had good dispersibility and workability.
Example B1
A ball mill having an inner diameter of 2m and a length of 30cm was charged with a compound containing 9.5kg of atomized aluminum powder of the raw material metal (average particle diameter: 2.4 μm), 45.8kg of mineral spirits and 570g of oleic acid, and the mixture was pulverized using 309kg of zirconia balls having a diameter of 0.8 mm.
As the zirconia balls, zirconia balls containing 94 mass% or more of ZrO 2 as a main component and having a round shape of 95% or more are used.
The rotation speed of the ball mill was set to 13rpm (the ratio of the rotation speed to the critical rotation speed was 43%), and the grinding in the 1 st stage was performed for 100 hours.
After grinding in the stage 1, 9.2kg of mineral spirits and 114g of oleic acid were added to the ball mill, and the grinding in the stage 2 was carried out over 6 hours with the rotation speed of the ball mill set to 23rpm (the ratio of the rotation speed to the critical rotation speed: 77%).
After the grinding, the slurry in the mill was washed out with mineral spirits and classified using a liquid cyclone classifier. The slurry was fed to a two-component separation type liquid cyclone classifier having a top nozzle diameter of 5mm, a bottom nozzle diameter of 2mm and a pressure of 0.4MPa, to obtain a slurry classified on the top side. The slurry obtained by classification was filtered through a filter and concentrated to obtain a cake containing 76 mass% of the heated residual component.
The obtained cake was transferred to a vertical mixer, and a predetermined amount of solvent naphtha was added thereto and mixed for 20 minutes to obtain an aluminum pigment having a heated residual component of 66 mass%.
The obtained aluminum pigment was evaluated for the average thickness, average length-thickness ratio, standard deviation of length-thickness ratio, number ratio of particles having length-thickness ratio of 20 or less, number ratio of particles having length-thickness ratio of 110 or more, number ratio of planar particles, arithmetic average height Sa of particle surface roughness, number ratio of particle diameter of 0.2 to 2.0 μm by the above (I) to (V), and the densification, brightness, dispersibility and glossiness by the above (VI) and (VII). The evaluation results are shown in Table B1.
Example B2
The starting metal atomized aluminum powder (average particle diameter: 2.5 μm) was used and the zirconium oxide balls having a diameter of 1.3mm were used for grinding.
The milling conditions for stage 1 are as follows: the rotation speed of the ball mill was set to 10rpm (the ratio of the rotation speed to the critical rotation speed was 33%), and grinding was performed for 60 hours.
The milling conditions for stage 2 were as follows: the rotation speed of the ball mill was set to 23rpm (the ratio of the rotation speed to the critical rotation speed was 77%), and grinding was performed for 10 hours. The same operation as in [ example B1] was performed under the other conditions to obtain an aluminum pigment having a heating residue of 68% by mass.
The obtained aluminum pigment was evaluated for a dense feel, brightness, lightness, dispersibility, and glossiness by the above-mentioned (VI) and (VII). The evaluation results are shown in Table B1.
Example B3
The starting metal atomized aluminum powder (average particle diameter: 2.3 μm) was used and the zirconium oxide balls having a diameter of 1.0mm were used for grinding.
The milling conditions for stage 1 are as follows: the rotation speed of the ball mill was set to 11rpm (the ratio of the rotation speed to the critical rotation speed was 37%), and the grinding was performed for 70 hours.
The milling conditions for stage 2 were as follows: the rotation speed of the ball mill was set to 23rpm (the ratio of the rotation speed to the critical rotation speed was 77%), and grinding was performed for 7 hours. The same operation as in example B1 was performed under the other conditions to obtain an aluminum pigment having 66 mass% of the heating residue.
The obtained aluminum pigment was evaluated for a dense feel, brightness, lightness, dispersibility, and glossiness by the above-mentioned (VI) and (VII). The evaluation results are shown in Table B1.
Example B4
The starting metal atomized aluminum powder (average particle diameter: 3.2 μm) was used and the zirconium oxide balls having a diameter of 1.7mm were used for grinding.
The milling conditions for stage 1 are as follows: the rotation speed of the ball mill was set to 10rpm (the ratio of the rotation speed to the critical rotation speed was 33%), and grinding was performed for 45 hours.
The milling conditions for stage 2 were as follows: the rotation speed of the ball mill was set to 23rpm (the ratio of the rotation speed to the critical rotation speed was 77%), and grinding was performed for 12 hours. The same operation as in [ example B1] was performed under the other conditions to obtain an aluminum pigment having a heating residue of 70% by mass.
The obtained aluminum pigment was evaluated for a dense feel, brightness, lightness, dispersibility, and glossiness by the above-mentioned (VI) and (VII). The evaluation results are shown in Table B1.
Example B5
The starting metal atomized aluminum powder (average particle diameter: 2.8 μm) was used and the zirconium oxide balls having a diameter of 1.3mm were used for grinding.
The milling conditions for stage 1 are as follows: the rotation speed of the ball mill was set to 12rpm (the ratio of the rotation speed to the critical rotation speed was 40%), and grinding was performed for 50 hours.
The same operation as in [ example B1] was performed under the other conditions to obtain 69 mass% of the aluminum pigment as a heating residue.
The obtained aluminum pigment was evaluated for a dense feel, brightness, lightness, dispersibility, and glossiness by the above-mentioned (VI) and (VII). The evaluation results are shown in Table B1.
Comparative example B1
The grinding conditions in stage 1 were as follows, using a material filled with the same compound as in the foregoing [ example B1 ]: the rotation speed of the ball mill was set to 6rpm (the ratio of rotation speed/critical rotation speed was 20%), and grinding was performed for 100 hours.
The milling conditions for stage 2 were as follows: the rotation speed of the ball mill was set to 6rpm (the ratio of the rotation speed to the critical rotation speed was 20%) in the same manner as in the 1 st stage, and grinding was carried out for 8 hours.
The same operation as in [ example B1] was performed under the other conditions to obtain an aluminum pigment having a heating residue of 70% by mass.
The obtained aluminum pigment was evaluated for a dense feel, brightness, lightness, dispersibility, and glossiness by the above-mentioned (VI) and (VII). The evaluation results are shown in Table B1.
Comparative example B2
The same raw material metal atomized aluminum powder as in the aforementioned [ example B1] was charged with a compound containing 42kg of mineral spirits and 950g of stearylamine, and pulverized using 408kg of stainless steel balls having a diameter of 0.8 mm.
The milling conditions for stage 1 are as follows: the rotation speed of the ball mill was set to 13rpm (the ratio of the rotation speed to the critical rotation speed was 43%), and grinding was performed.
After grinding in the stage 1, 8.4kg of mineral spirits and 190g of stearyl amine were added to the ball mill, and the rotation speed of the ball mill was set to 23rpm (rotation speed/critical rotation speed ratio: 77%), followed by grinding in the stage 2 over 8 hours.
The same operation as in [ example B1] was performed under other conditions to obtain an aluminum pigment having a heating residue of 64% by mass.
The obtained aluminum pigment was evaluated for a dense feel, brightness, lightness, dispersibility, and glossiness by the above-mentioned (VI) and (VII). The evaluation results are shown in Table B1.
Comparative example B3
The grinding in stage 1 was carried out using a raw material metal atomized aluminum powder (average particle diameter: 6.2 μm).
The milling conditions for stage 2 were as follows: the rotation speed of the ball mill was set to 6rpm (the ratio of rotation speed/critical rotation speed was 20%), and grinding was performed for 8 hours.
The other compounds and grinding conditions were subjected to the same procedure as in [ example B1 ].
After the completion of grinding, the slurry in the mill was refined with mineral oil, coarse particles were removed by a 400-mesh vibrating screen, and the mixture was filtered and concentrated by a filter to obtain a cake containing 78% by mass of the heated residual component (classification step was not performed).
The obtained cake was transferred to a vertical mixer, and a predetermined amount of solvent naphtha was added thereto and mixed for 20 minutes to obtain an aluminum pigment having a heating residue content of 68 mass%.
The obtained aluminum pigment was evaluated for densification, brightness, lightness, dispersibility, and glossiness by the above-mentioned (VI) and (VII). The evaluation results are shown in Table B1.
Comparative example B4
The aluminum pigment obtained by the metal vapor deposition method (without grinding step and classification step) of Metalure L55700,55700 manufactured by Eckart was evaluated for densification, brightness, lightness, dispersibility, and glossiness by the above-mentioned (VI) and (VII). The evaluation results are shown in Table B1.
[ Table B1]
Table B1
From the results shown in Table B1, it is clear that the aluminum pigment of the present invention is dense, and has extremely high brightness, brightness and glossiness, and good dispersibility and workability.
Industrial applicability
The aluminum pigment of the present invention is industrially useful as a material for mixing a high-grade metal resin in the fields of high-grade metal coating materials for automobile bodies, automobile interior parts, automobile repair metal coating materials, metal coating materials for home use, metal coating materials for optical instruments such as cellular phones, smart phones, PCs, flat panels, cameras, televisions, and the like, PCM, industrial metal coating materials, high-grade metal printing inks such as gravure printing, offset printing, screen printing, and the like.
Claims (12)
1. An aluminum pigment wherein the average thickness of metallic aluminum particles is 0.02 to 0.20 mu m, the average aspect ratio, i.e., the particle cross-sectional length/particle cross-sectional thickness is 40 to 100, and the standard deviation of the aspect ratio is 15 to 70.
2. The aluminum pigment according to claim 1, wherein the ratio of the number of particles having a length to thickness ratio of 20 or less is 30% or less relative to the whole.
3. The aluminum pigment according to claim 1 or 2, wherein the ratio of the number of particles having a length to thickness ratio of 110 or more to the whole is 30% or less.
4. An aluminum pigment according to any one of claims 1 to 3, wherein the arithmetic mean height Sa of the surface roughness of the particles is 2 to 15nm.
5. The aluminum pigment according to any of claims 1 to 4, wherein the average thickness of the particles is 0.03 to 0.15 μm.
6. The aluminum pigment according to any of claims 1 to 5, wherein the average aspect ratio of the particles is 40 to 90.
7. The aluminum pigment according to any one of claims 1 to 6, which contains the metal aluminum particles having a particle diameter of 0.2 to 2.0 μm in a number ratio of 15 to 70% of the total metal aluminum particles.
8. The aluminum pigment according to any one of claims 1 to 7, which contains the planar particles having a planeness of the particles, i.e., a shortest length/particle cross-sectional length of 0.95 to 1.00, in a number ratio of 60% or more.
9. A process for producing the aluminum pigment according to any one of claims 1 to 8, comprising: a step of grinding the raw material metal aluminum powder by a grinding device, and a step of classifying the ground slurry.
10. The method for producing an aluminum pigment according to claim 9, wherein the step of grinding is performed in 2 stages.
11. A coating composition comprising the aluminum pigment of any one of claims 1 to 8.
12. An ink composition comprising the aluminum pigment according to any one of claims 1 to 8.
Applications Claiming Priority (4)
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| JP2021-147252 | 2021-09-10 | ||
| JP2022-033210 | 2022-03-04 | ||
| JP2022033210 | 2022-03-04 | ||
| PCT/JP2022/033291 WO2023038009A1 (en) | 2021-09-10 | 2022-09-05 | Aluminum pigment, method for producing aluminum pigment, coating material composition containing aluminum pigment, and ink composition |
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| CN117957286A true CN117957286A (en) | 2024-04-30 |
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