JP2022150635A - metal pigment composition - Google Patents

Abstract

To provide a new metal pigment composition.SOLUTION: A metal pigment composition in this invention includes a composite particle having a metal particle and at least one coating layer on the surface thereof, and satisfies the following conditions (1) to (6): (1) the composite particle has a scaly shape; (2) D50 of volume standard when measuring the particle size distribution of the composite particle using a laser diffraction type particle size distribution meter is 3 μm or more but 30 μm or less; (3) the average thickness of the composite particle is 20 nm or more but 300 nm or less; (4) at least one layer of the coating layer includes a silicon compound; (5) in the composite particle, the ratio of a silicon content based on the coating layer to a metal element content based on the metal particle is 0.02 or more but 0.3 or less ; and (6) the number ratio of the composite particle having a particle size of 0.1 μm or more but 1 μm or less to the total amount of the composite particle occupying in the metal pigment composition, is 10% or less.SELECTED DRAWING: None

Description

The present invention relates to a metal pigment composition containing novel composite particles. More specifically, the present invention provides novel composite particles having excellent paint stability, storage stability, paint film color tone (specifically, brightness, flip-flop feeling, hiding property), and paint adhesion. It relates to a metal pigment composition comprising

BACKGROUND ART Conventionally, metallic pigments have been used for metallic paints, printing inks, kneading into plastics, and the like, for the purpose of obtaining a cosmetic effect that emphasizes a metallic feeling.
In recent years, in the field of paints, there is a growing need to switch to water-based paints that use less organic solvents as a measure to conserve resources and eliminate pollution. There are not enough types of water-based paints. The reason for this is that metal pigments are easily corroded in water-based paints. When metal powder is present in water-based paint or water-based ink, corrosion by water occurs in either acidic, neutral, basic, or multiple regions based on the properties of various metals, and hydrogen gas is generated. do. In particular, it is an extremely serious problem in terms of safety in paint and ink manufacturing processes at paint and ink manufacturers, and in painting and printing processes at automobile manufacturers, home appliance manufacturers, printer manufacturers, and the like.
Since the corrosiveness of metal pigments poses a problem in terms of storage stability, the corrosion resistance of metal pigments can be rephrased as storage stability.
In addition, since the smoothness of the metal surface is lost due to corrosion, the color tone when used as a coating film, that is, the coating film color tone (specifically, the brightness, the flip-flop feeling, and the hiding property) is inevitably reduced. In addition, in recent years, due to the diversification of color design, there is a high demand for metallic paints that can provide a finish with a strong luster. (which is a parameter dependent on the degree of orientation of the metal pigment) is desired.
In addition, when a metallic pigment is used as a paint, the aggregating property of the pigment (specifically, the aggregating property of individual particles constituting the pigment) is required to be small, that is, the paint stability is required.
In addition, when the metal pigment is made into a paint to form a coating film, it is required not to reduce the adhesion to the substrate, that is, the paint adhesion.

In Patent Document 1 (International Publication No. 2020/21735 pamphlet), when an aluminum pigment that has not been subjected to surface treatment is used as a paint or printing ink, the problem of low adhesion to the resin in the coating film is solved. Therefore, a resin-coated metal pigment having a minute average particle size and using a predetermined copolymer as a coating resin has been disclosed.
In addition, in Patent Document 2 (International Publication No. 2019/77904 pamphlet), from the viewpoint of providing a new design and a high-class metallic feeling, the particle size is 1 μm or less. In the microscope image observed using , the ratio of the number of the small-diameter aluminum flakes to the total number of the aluminum flakes is 35% or less.
However, none of the above-described coating stability, storage stability, coating color tone (specifically, light brightness, flip-flop feeling, hiding property), and coating The current situation is that it is difficult to provide adhesion, and development of a metal pigment composition containing novel composite particles is desired.

WO 2020/21735 pamphlet International Publication No. 2019/77904 Pamphlet

An object of the present invention is to provide a metal pigment composition containing novel composite particles not found in the prior art.
A further object of the present invention is to solve the problems of the prior art, namely, paint stability, storage stability, paint film color tone (specifically, brightness, flip-flop feeling, hiding property), and paint adhesion. An object of the present invention is to provide a metal pigment composition containing novel composite particles having excellent properties.

As a result of intensive research, the present inventors have found a metal pigment composition comprising metal particles and composite particles having a coating layer containing one or more silicon compound-containing layers (i.e., silica layers) on the surface thereof, wherein the composite The particles are shaped like scales, and the average thickness of the composite particles (specifically, the size (particle diameter) of the metal particles that are the core of the composite particles and the silica layer that constitutes the coating layer on the surface) thickness) is within a certain range, and in addition to controlling the volume-based _D50 in the particle size distribution of the composite particle to be within a predetermined range, the metal that is the core particle of the composite particle According to the metal pigment composition in which the ratio of the silicon content based on the silica layer to the metal element content based on the particles and the number ratio of the composite particles having a predetermined fine particle size are controlled within a predetermined range, the above We have found that the problem can be solved.
In addition, the present inventors have found that in the composite particles containing the metal pigment composition, a coating layer containing one or more silicon compound-containing layers (i.e., silica layers) is formed on the surface of the metal particles serving as the core of the composite particles. In this case, while a silica layer with a certain thickness is required to exhibit corrosion resistance, as the size (particle diameter) of the composite particles increases, the metal particles that become the core also become smaller. The thickness of the silica layer becomes relatively large, which hinders the orientation of the metal pigment, making it difficult to exhibit the original optical performance of the metal particles, and the size (particle diameter) of the composite particles is very small. It has been found that the metal pigment composition described above can solve the problem that the adhesion between the base material and the paint is hindered and the adhesion of the base material of the paint resin is lowered when the amount is increased.

That is, aspects of the present invention are as follows.
[Aspect 1]
A metal pigment composition comprising composite particles having metal particles and one or more coating layers on the surface thereof,
(1) the shape of the composite particles is scaly,
(2) a volume-based _D50 of 3 μm or more and 30 μm or less when the particle size distribution of the composite particles is measured with a laser diffraction particle size distribution meter;
(3) the average thickness of the composite particles is 20 nm or more and 300 nm or less;
(4) at least one layer of the coating layer is a silicon compound-containing layer;
(5) In the composite particles, the ratio of the metal element content based on the metal particles to the silicon content based on the coating layer is 0.02 or more and 0.3 as a ratio of the silicon content to the metal element content. and
(6) The number ratio of the composite particles having a particle size of 0.1 μm or more and 1 μm or less is 10% or less of the total number of the composite particles in the metal pigment composition.
The above metal pigment composition.
[Aspect 2]
When the particle size distribution of the composite particles is measured with the laser diffraction particle size distribution meter, the number ratio of the composite particles having a particle size of 3 times or more the _D50 on a volume basis is the metal pigment composition. The metal pigment composition according to [Aspect 1] above, which accounts for 3% or less of the total number of the composite particles in the product.
[Aspect 3]
The metal pigment composition according to [Aspect 1] or [Aspect 2] above, wherein the metal particles are aluminum or an aluminum alloy.
[Aspect 4]
The metal pigment composition according to any one of [Aspect 1] to [Aspect 3] above, further comprising a coating layer comprising at least one of metal, metal oxide, metal hydrate and resin.
[Aspect 5]
The metal pigment composition according to any one of [Aspect 1] to [Aspect 4] above, wherein at least the silicon compound-containing layer is disposed as the outermost layer.
[Aspect 6]
A water-based metallic paint comprising the metallic pigment composition according to any one of [Aspect 1] to [Aspect 5].
[Aspect 7]
An aqueous metallic coating film comprising the metallic pigment composition according to any one of [Aspect 1] to [Aspect 5].

According to the present invention, it is possible to provide a metal pigment composition containing novel composite particles not found in the prior art.
According to a preferred embodiment of the present invention, the paint stability (specifically, when the pigment is used as a paint, the individual particles that make up the pigment have little cohesiveness), storage stability (specifically Specifically, the property that the generation of hydrogen gas due to corrosion can be suppressed), the paint film color tone (specifically, the properties of high brightness, flip-flop feeling, and high hiding power), and the paint adhesion (specifically, , the properties of high adhesion to a substrate when the metal pigment is made into a paint to form a coating film) can be provided.

The present invention will be described below along typical or preferred embodiments, but the present invention is not limited to these embodiments. Unless explicitly indicated, these embodiments are freely combinable within the scope of the invention as defined in the appended claims.

1. Composite Particles Contained in the Metal Pigment Composition The metal pigment composition according to the present invention comprises composite particles having metal particles and one or more coating layers thereon.
As used herein, the term "metallic pigment composition" means that composite particles comprising metal particles and one or more coating layers on the surface thereof are dispersed in a solvent comprising water and/or a hydrophilic solvent, or is accompanied by a solvent, including water and/or a hydrophilic solvent, and may optionally contain other ingredients.
In the present specification, a composition obtained by adding a resin to a metallic pigment composition is distinguished from the term "metallic pigment composition" by the term "resin composition" or "resin composition containing a metallic pigment composition". sometimes referred to as

Metal Particles The composite particles contained in the metal pigment composition according to the present invention comprise metal particles and one or more coating layers formed on the surfaces thereof. That is, one or more coating layers are formed on the surface of the metal particles that form the core of the composite particles.

The material of the metal particles (core particles) that make up the composite particles is not particularly limited. Alternatively, any metal used as a commercially available metal pigment may be used. In this specification, the metal of the metal particles constituting the composite particles includes not only simple metals but also alloys and intermetallic compounds.
As described above, the metal particles may be composed of a single metal composed of only one metal element, or a combination of two or more metals composed of only one metal element (i.e., two or more metals elemental metals) may also be used.
The metal particles in the present invention are preferably metal containing aluminum as a main component, such as aluminum or an aluminum alloy, more preferably aluminum.

Although the shape of the metal particles is not limited, it is particularly desirable that they are scaly (flaky). As a result, the composite particles contained in the metal pigment composition according to the present invention can also have a scaly shape, and as a result, high hiding power and the like can be obtained more reliably. From this point of view, the aspect ratio (shape factor obtained by dividing the average particle size by the average thickness) of the scaly metal particles is preferably 20 or more and 30 or less. When the aspect ratio of the metal particles is 20 or more, a higher feeling of brightness can be obtained. In addition, when the aspect ratio of the metal particles is 3000 or less, the mechanical strength of the flakes is maintained, and a stable color tone can be obtained. Here, the average thickness of the metal particles used in the present invention can be calculated from the water surface diffusion area and density of the metal particles.

The average particle size of the metal particles is not particularly limited as long as the average particle size can provide _D50 in the particle size distribution of the composite particles described later. That is, it is desirable to set the average particle size of the metal particles so that the composite particles have a _D50 of 3 μm or more and 30 μm or less when the volume distribution is measured with a laser diffraction particle size distribution meter.
The average particle size of the metal particles is determined by the process of grinding, sieving, and filtering the raw atomized metal powder (e.g., aluminum powder) using a ball mill or the like. It can be controlled by appropriately adjusting the mass per piece, the rotation speed of the grinding device, the degree of sieving and filter pressing, and the like.

In addition, the metal particles do not necessarily have to be composed of metal only, and as long as the effects of the present invention are not hindered, for example, inorganic particles such as synthetic resin particles, mica, glass, etc., whose surfaces are coated with metal, etc. can also be used. In the present invention, particles formed from aluminum or an aluminum alloy are desirable in terms of particularly high weather resistance, low specific gravity, easy availability, and the like.

Aluminum flakes, which are commonly used as metallic pigments, are particularly suitable as the metal particles constituting the composite particles. As the aluminum flakes, those having surface properties such as surface glossiness, whiteness, luster, etc., particle size, and shape required for metallic pigments are suitable. Aluminum flakes are usually commercially available in paste form. Paste-like aluminum flakes usually contain scale-like aluminum powder, mineral spirits (aliphatic hydrocarbons) used during pulverization, residual fatty acids, and organic solvents such as solvent naphtha and xylene. you can stay The paste-like aluminum flakes may be used as they are, or may be used after removing the fatty acid or the like from the surface in advance with an organic solvent or the like.
In addition, a so-called aluminum-deposited foil can also be used, which has a volume average particle size (D ₅₀ ) of 3 μm or more and 30 μm or less and an average thickness of 20 nm or more and 300 nm or less in the state of composite particles.

2. Desirable Physical Properties of Metal Pigment Composition The metal pigment composition according to the present invention is characterized by further satisfying the following physical property requirements.
(1) The shape of the composite particles is scaly,
(2) the volume-based _D50 when the particle size distribution of the composite particles is measured with a laser diffraction particle size distribution meter is 3 μm or more and 30 μm or less;
(3) the average thickness of the composite particles is 20 nm or more and 300 nm or less;
(4) at least one of the coating layers is a silicon compound-containing layer;
(5) In the composite particles, the ratio of the metal element content based on the metal particles to the silicon content based on the coating layer is 0.02 or more and 0.3 as a ratio of the silicon content to the metal element content. be
(6) The number ratio of the composite particles having a particle size of 0.1 μm or more and 1 μm or less is 10% or less of the total number of the composite particles in the metal pigment composition.
Each of these physical property requirements will be described below.

(1) The shape of the composite particles is scale-like The shape of the composite particles of the metallic pigment composition according to the present invention is scale-like (flake-like). As a result, the coating film formed using the metal pigment composition can exhibit high brightness, high flip-flop feeling, high hiding power, and the like. In this specification, the shape of the composite particles is “scaly” (flaky), which means that the average aspect ratio (shape factor obtained by dividing the average particle diameter by the average thickness) of the composite particles is 10 or more. shall be The average aspect ratio of the scale-like composite particles is preferably 10 or more and 1,500 or less from the viewpoint of obtaining high brightness, flip-flop feeling, concealability, and the like. When the average aspect ratio is 10 or more, a sufficient feeling of glitter can be exhibited, while when the average aspect ratio is 1500 or less, the mechanical strength of the flakes can be maintained and a stable color tone can be obtained.
The "composite particles" in the physical property requirement (1) refer to aggregates (aggregates) when a plurality of composite particles are aggregated and adhered.
Here, the average particle diameter for calculating the average aspect ratio of the composite particles is the volume-based _D50 called the median diameter, and this point will be described in detail in the description of requirement (2) below. Also, the average thickness for calculating the average aspect ratio of the composite particles will be described in detail in the description of requirement (3) below.

(2) When the particle size distribution of the composite particles is measured with a laser diffraction particle size distribution meter, the volume-based _D50 is 3 μm or more and 30 μm or less The particle size distribution of the composite particles was measured with a laser diffraction particle size distribution meter. In this case, the volume-based _D50 is 3 μm or more and 30 μm or less. As a result, the coating film formed using the metal pigment composition exhibits high brightness, high flip-flop feeling, high hiding power, etc., and also suppresses aggregation of individual particles that make up the metal pigment composition. and its cohesiveness can be reduced. This volume-based _D50 is also commonly referred to as the median diameter.
From the viewpoint of obtaining such high light brightness, high flip-flop feeling, high hiding power and small cohesiveness of individual particles, the volume-based D when measuring the particle size distribution of the composite particles with a laser diffraction particle size distribution meter ₅₀ has a lower limit of 3 μm or more and an upper limit of 30 μm or less, preferably 25 μm or less, more preferably 20 μm or less.
The “composite particles” in the physical property requirement (2) refer to aggregates (aggregates) when a plurality of composite particles are aggregated and adhered.
Here, the volume-based D50 when the particle size distribution of the composite particles is measured with a laser diffraction particle size distribution meter refers to the particle size with a cumulative degree of ₅₀ % in the volume cumulative particle size distribution. The laser diffraction particle size distribution meter is not particularly limited, but for example, "LA-300" (manufactured by HORIBA, Ltd.) can be used. Mineral spirits can be used as the measuring solvent. For example, after performing ultrasonic dispersion for 2 minutes as a pretreatment on the metal pigment composition containing the sample composite particles, it is put into a dispersion tank and after confirming that it is properly dispersed, _D50 is measured. can do.
The particle size of the composite particles in the resin composition described below cannot be measured by this method. Therefore, as an alternative method in this case, for example, the composite particles in the resin composition are photographed from the coating surface with an optical microscope, a laser microscope, etc., and commercially available image analysis software is used to obtain the distribution of the equivalent circle diameter. It is possible to adopt a method of determining the particle size by
The volume-based _D50 of the composite particles contained in the metal pigment composition is obtained by grinding, sieving, and filtering the raw material atomized metal powder (e.g., aluminum powder) using a ball mill or the like in the method for producing the metal pigment composition described later. By appropriately adjusting the particle diameter of the raw material atomized metal powder, the mass per grinding ball when using a ball mill, the rotation speed of the grinding device, the degree of sieving and filter pressing, etc., and , in the step of coating the silicon compound-containing layer (and other coating layers as necessary), in the type of organosilicon compound used, in the coating step (if the organosilicon compound is hydrolyzed and used, that step is also included) pH, concentration, stirring temperature, stirring time, type of stirring device, power/degree of stirring (type and diameter of stirring blade, number of revolutions, presence/absence of external stirring, etc.), etc. can be controlled as appropriate. can.

(3) The composite particles have an average thickness of 20 nm or more and 300 nm or less. The average thickness of the composite particles having a layer is desirably 20 nm or more and 300 nm or less. As a result, together with the satisfaction of the above requirements (1) to (2), the coating film formed using the metal pigment composition exhibits higher brightness, higher flip-flop feeling, higher hiding power, etc. At the same time, aggregation of individual composite particles constituting the metal pigment composition is suppressed, and the aggregation can be reduced.
In addition, together with the satisfaction of the requirements (4) to (6) described later, it exhibits high corrosiveness even when used for water-based metallic paints and metallic coating films, and is suitable for coating films such as metallic coating films. Even when used, excellent adhesion can be exhibited.
From the above viewpoint, the average thickness of the composite particles has a lower limit of 20 nm or more and an upper limit of 300 nm or less, preferably 200 nm or less.
The "composite particles" in the physical property requirement (3) refer to aggregates (aggregates) when a plurality of composite particles are aggregated and adhered.
The average thickness of the composite particles here can be calculated from the water surface diffusion area and density of the composite particles. The water surface diffusion area refers to the area occupied by the dry composite particles per unit mass when the dried composite particles are uniformly diffused on the water surface using the leafing phenomenon and covered without gaps. The water surface diffusion area can be measured according to JIS K5906:1998.
However, with the composite particles of the present invention, it may be difficult to determine the water surface diffusion area when the surface is highly hydrophilic. In this case, the average thickness of the composite particles can be measured according to the method described in the examples below. That is, a coating (thin film) is formed using a metal pigment composition in which the composite particles are dispersed in a mixture of an alcoholic solvent such as methoxypropanol and water, and the composite particles (500 or more) are observed with a scanning electron microscope (SEM). By observing the thickness of the composite particles, the average thickness of the composite particles can be obtained.
The average thickness of the composite particles contained in the metallic pigment composition is obtained by grinding raw material atomized metal powder (for example, aluminum powder) using a ball mill or the like in the method for producing the metallic pigment composition described later, similarly to the volume-based _D50 . And in the sieving and filtering process, the particle size of the raw material atomized metal powder, the mass of each grinding ball when using a ball mill, the number of revolutions of the grinding device, the degree of sieving and filter pressing, etc. are adjusted as appropriate. and in the step of coating the silicon compound-containing layer (and other coating layers as necessary), the type of organosilicon compound used, the coating step (if the organosilicon compound is hydrolyzed and used, its pH, concentration, stirring temperature, stirring time, type of stirring device, power/degree of stirring (e.g., type and diameter of stirring blade, number of revolutions, presence/absence of external stirring), etc. can be controlled by

(4) At least one coating layer is a silicon compound-containing layer In the metal pigment composition according to the present invention, at least one coating layer formed on the surface of the metal particle serving as the core of the composite particle One layer is a silicon compound-containing layer. As a result, gas generation in the water-based paint can be suppressed, good storage stability (that is, corrosion resistance) can be obtained, and excellent water resistance can be obtained when the paint film is formed.
In addition, together with the satisfaction of the requirements (1) to (3) described above and the requirements (5) to (6) described later, high light luminance is obtained even when used in a water-based metallic paint to form a metallic coating film or the like. In addition to exhibiting an excellent coating film color tone due to a high flip-flop feeling and a high hiding property, it can exhibit excellent adhesion when used for a coating film such as a metallic coating film.
The coating layer of the composite particles may have another coating layer (second coating layer) in addition to the silicon compound-containing layer. Such a second coating layer will be further described later.

The silicon compound-containing layer is preferably a layer composed of a compound containing Si—O—bonds (siloxane bonds). Examples of such a layer include a layer containing at least one of a silane compound and silicon oxide. Examples of such compounds include silane-based compounds [H ₃ SiO(H ₂ SiO) _n SiH ₃ ] (where n represents an arbitrary positive integer), SiO ₂ , SiO ₂ ·nH ₂ O ( However, n represents any positive integer.) and the like are exemplified. These silane-based compounds and silicon oxides may be either crystalline or amorphous, but are preferably amorphous. Therefore, as the layer containing silicon oxide (silica etc.), for example, a layer containing amorphous silica can also be suitably employed.

Also, the layer composed of a compound containing Si—O bonds may be a layer formed using an organosilicon compound (including a silane coupling agent) as a starting material. In this case, the silicon compound-containing layer may contain an organosilicon compound or a component derived therefrom as long as the effects of the present invention are not impaired. Typically, layers composed of compounds containing Si—O bonds can be formed by hydrolyzing organosilicon compounds.

The silicon compound-containing layer may contain additives, impurities, etc. other than the silicon compound as long as the characteristics of the present invention are not impaired.

The silicon content in the silicon compound-containing layer is not particularly limited as long as it satisfies requirement (5) described later.

The coating layer of the composite particles contained in the metal pigment composition according to the invention is particularly preferably hydrophilic. The composite particles usually form a metal pigment composition dispersed in an aqueous solvent (water or a mixed solvent containing water and an organic solvent). is highly dispersible in such aqueous solvents. Moreover, since silicon oxides (such as amorphous silica) are very stable in aqueous solvents, it is possible to provide a metal pigment composition containing composite particles that are highly stable in aqueous solvents. From this point of view, it is desirable that at least the outermost layer of the composite particles contained in the metal pigment composition of the present invention is a silicon compound-containing layer (especially a layer composed of a compound containing Si—O bonds). When the coating layer is composed of a plurality of layers, in addition to the silicon compound-containing layer as the outermost layer, a silicon compound-containing layer (especially a Si—O-based coating layer) may be separately formed as a layer other than the outermost layer. .

The thickness of the coating layer of each composite particle is not particularly limited as long as the average thickness of the composite particles is in the range of 20 nm or more and 300 nm or less as described above, but it is usually about 5 to 50 nm (especially 10 nm or more and 40 nm or less, and further 15 nm or more and 30 nm or less). When the thickness of the coating layer is 1 nm or more, it is possible to obtain a coating film that has sufficient water resistance and suppresses the occurrence of corrosion or discoloration of metal particles in water-based paint. On the other hand, when the thickness of the coating layer is about 50 nm or less, the brightness, sharpness, and hiding power of the coating film can be maintained at a high level.

The thickness of the silicon compound-containing layer contained in the coating layer of each composite particle is also not particularly limited as long as the average thickness of the composite particles is in the range of 20 nm or more and 300 nm or less as described in the above requirement (3). From the viewpoint of the function of the layer, the thickness is usually in the range of 5 nm or more and 50 nm or less, and particularly preferably in the range of 10 nm or more and 40 nm or less.

Specific examples of the organosilicon compound that can be used in the present invention are further described below, but the organosilicon compound is not limited to these specific examples.
The organosilicon compound comprises at least one organosilicon compound represented by the following general formula (1), a silane coupling agent represented by any one of the following general formulas (2), (3) and (4), and and at least one selected from partial condensates thereof.

Si(OR ¹ ) ₄ (1)
(In the formula, R ¹ is a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and all R ^1s may be the same, some may be the same, or all may be different.)
R ² _m Si(OR ³ ) _4-m (2)
(Wherein, R ² is a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms which may optionally contain a halogen group, and R ³ is a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms R ² and R ³ may be the same or different, and when there are two or more R ² or R ³ , all of them may be the same, some of them may be the same, or all of them may be different. 1≤m≤3.)
R ⁴ _p R ⁵ _q Si(OR ⁶ ) _4-pq (3)
(Wherein, R ⁴ is a group containing a reactive group capable of chemically bonding with other functional groups, and R ⁵ is a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, which may optionally contain a halogen group. and R ⁶ is a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms.When there are two or more R ⁴ , R ⁵ , or R ⁶ , all or part of , all may be different, 1 ≤ p ≤ 3, 0 ≤ q ≤ 2, 1 ≤ p + q ≤ 3.)
R ⁷ _r SiCl _4-r (4)
(In the formula, R ⁷ is a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms which may optionally contain a halogen group, and when there are two or more R ⁷ , even if all are the same, some may be the same or all may be different, 0≦r≦3.)

Examples of hydrocarbon groups for R ¹ in formula (1) include methyl, ethyl, propyl, butyl, hexyl, octyl, etc., which may be branched or linear. Among these hydrocarbon groups, methyl, ethyl, propyl and butyl are particularly preferred. In addition, all four R ¹ 's may be the same, some may be the same, or all may be different.
Preferred examples of such organosilicon compounds of formula (1) include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, and the like. Among these, tetraethoxysilane is particularly preferred.

Examples of hydrocarbon groups for R ² in formula (2) include methyl, ethyl, propyl, butyl, hexyl, octyl, decyl, dodecyl, oleyl, stearyl, cyclohexyl, phenyl, benzyl, naphthyl, etc., which are It may be branched or linear, and may contain halogen groups such as fluorine, chlorine, and bromine. Among these, hydrocarbon groups having 1 to 18 carbon atoms are particularly preferred. Moreover, when there are two or more R ² , they may all be the same, some of them may be the same, or all of them may be different. The number of R ² in the molecule is m=1 to 3, that is, 1 to 3 in formula (2), but m=1 or 2 is more preferable.
Examples of hydrocarbon groups for R ³ in formula (2) include methyl, ethyl, propyl, butyl, hexyl, octyl, etc., which may be branched or linear. Among these hydrocarbon groups, methyl, ethyl, propyl and butyl are particularly preferred. Moreover, when there are ^two or more R3's, they may all be the same, some of them may be the same, or all of them may be different.
Preferred examples of such organosilicon compounds (silane coupling agents) of formula (2) include methyltrimethoxysilane, methyltriethoxysilane, methyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldibutoxysilane, silane, trimethylmethoxysilane, trimethylethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltributoxysilane, butyltrimethoxysilane, butyltriethoxysilane, butyltributoxysilane, dibutyldimethoxysilane, Dibutyldiethoxysilane, dibutyldibutoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, dihexyldimethoxysilane, dihexyldiethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, dioctyl Dimethoxysilane, dioctyldiethoxysilane, dioctylethoxybutoxysilane, decyltrimethoxysilane, decyltriethoxysilane, didecyldimethoxysilane, didecyldiethoxysilane, octadecyltrimethoxysilane, octadecyltriethoxysilane, dioctadecyldimethoxysilane, di Octadecyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, trifluoropropyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, tridecafluorooctyltrimethoxysilane, tridecafluoro octyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 3-chloropropyltributoxysilane and the like.

Examples of reactive groups that can chemically bond with other functional groups in R ⁴ of formula (3) include vinyl groups, epoxy groups, styryl groups, methacryloxy groups, acryloxy groups, amino groups, ureido groups, mercapto groups, and polysulfide groups. , an isocyanate group, and the like.
Moreover, when there are two or more ^R4 's, they may all be the same, some of them may be the same, or all of them may be different. The number of ^R4 's in the molecule is p=1 to 3, that is, 1 to 3 in formula (3), but p=1 is more preferable.
Examples of hydrocarbon groups for R ⁵ in formula (3) include methyl, ethyl, propyl, butyl, hexyl, octyl, decyl, dodecyl, oleyl, stearyl, cyclohexyl, phenyl, benzyl, naphthyl and the like, which are It may be branched or linear, and may contain halogen groups such as fluorine, chlorine, and bromine. Among these, hydrocarbon groups having 1 to 18 carbon atoms are particularly preferred. Moreover, when there are two or more R ⁵ , they may all be the same, some of them may be the same, or all of them may be different.
Examples of hydrocarbon groups for R ⁶ in formula (3) include methyl, ethyl, propyl, butyl, hexyl, octyl, etc., which may be branched or linear. Among these hydrocarbon groups, methyl, ethyl, propyl and butyl are particularly preferred. Moreover, when there are two or more R ⁶ , they may all be the same, some of them may be the same, or all of them may be different.

Preferred examples of such organosilicon compounds (silane coupling agents) of formula (3) include vinyltrimethoxysilane, vinyltriethoxysilane, vinyl-tris(2-methoxyethoxy)silane, 2-(3,4 -epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacrylic roxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, N-methyl-3-amino Propyl-trimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3 -aminopropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3- aminopropyltrimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, 3-ureidopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyl-triethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatopropyltriethoxysilane and the like.

Examples of hydrocarbon groups for R ⁷ in formula (4) include methyl, ethyl, propyl, butyl, hexyl, octyl, decyl, dodecyl, oleyl, stearyl, cyclohexyl, phenyl, benzyl, naphthyl, etc., which are It may be branched or linear, and may contain halogen groups such as fluorine, chlorine, and bromine. Among these, hydrocarbon groups having 1 to 12 carbon atoms are particularly preferred. Moreover, when there are two or more R ⁷ , they may all be the same, some of them may be the same, or all of them may be different. The number of ^R7 in the molecule is r=0 to 3, ie, 0 to 3 in formula (4), and more preferably r=1 to 3.
Preferred examples of such organosilicon compounds (silane coupling agents) of formula (4) include methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, octyldimethylchlorosilane, phenyltrichlorosilane, vinyltrichlorosilane, tetrachlorosilane, and the like. mentioned.

The organosilicon compounds represented by the general formula (1) may be used alone or in combination of two or more. Also, the silane coupling agents represented by any of the general formulas (2), (3) and (4) may be used alone or in combination of two or more. good too. When two or more are used in combination, only the silane coupling agents represented by any one of (2), (3) and (4) may be used in combination of two or more, Silane coupling agents represented by two or more different general formulas may be used in combination.

The hydrolyzate and/or condensation reaction product of the organosilicon compound can be obtained by stirring and mixing the organosilicon compound, a necessary amount of water for the hydrolysis reaction, and a hydrolysis catalyst. In that case, a hydrophilic solvent can also be used as needed. Various conditions for the hydrolysis reaction (that is, the reaction for forming the silicon compound-containing layer) will be described later.

As raw materials for the hydrolysis reaction and/or the condensation reaction for obtaining the hydrolyzate and/or the condensation reaction product of the organosilicon compound, a preliminarily partially condensed oligomer may be used.
The condensation reaction of the hydrolyzate of the organosilicon compound may be carried out simultaneously with the hydrolysis reaction of the organosilicon compound, or may be carried out in separate steps with a different catalyst if necessary. In that case, you may heat as needed.

The coating layer of the composite particles contained in the metal pigment composition according to the present invention is not particularly limited except that at least one layer is a silicon compound-containing layer. layers") may be formed as desired.
The second coating layer includes, for example, metals (alkali metals; alkaline earth metals; metals such as manganese, iron, cobalt, nickel, copper, and silver), metal oxides (titanium oxide, zirconium oxide, iron oxide, etc.), metal It may contain at least one of hydrates and resins (synthetic resins such as acrylic resins, alkyd resins, polyester resins, polyurethane resins, polyvinyl acetate resins, nitrocellulose resins, and fluorine resins). As the second coating layer, for example, a molybdenum-containing coating, a phosphoric acid compound coating, or the like can be formed. By providing the second coating layer, it is possible to improve the corrosion resistance of the metal particles and promote the formation of the silicon compound-containing layer.
The second coating layer (if formed) is preferably formed especially between the metal particles and the silicon compound-containing layer. Therefore, for example, a layer structure of "metal particles/second coating layer/silicon compound-containing layer" can be preferably adopted. Although not particularly limited, examples of molybdenum-containing coatings include those disclosed in JP-A-2003-147226, WO-2004/096921, JP-A-5979788, and JP-A-2019-151678. can be done. An example of the phosphate compound coating is disclosed in Japanese Patent No. 4633239. Preferred examples of the molybdenum-containing material constituting the molybdenum-containing coating include the mixed coordination heteropolyanion compound disclosed in JP-A-2019-151678.
In another variation, a second coating layer can be formed on the outside of the metal particles and the silicon compound-containing layer. In yet another variation, the components of the second coating layer (such as molybdenum-containing compounds and phosphate compounds) can be included with the silicon compound in the silicon compound-containing layer.

The mixed-coordination heteropolyanion compound used in the embodiment of forming the second coating layer (typically a molybdenum-containing coating) other than the silicon compound-containing layer of the composite particles contained in the metal pigment composition according to the present invention is particularly Specific examples include, but are not limited to, the following.

The mixed-coordination heteropolyanion of the mixed-coordination heteropolyanion compound that can be used has a structure in which some of the polyatoms of a heteropolyanion composed of one element are replaced by another element, It exhibits different physical properties from the mixture of each heteropolyanion.

In terms of chemical formulas, when the mixed-coordination _{heteropolyanion is} ^{expressed as [XpMqNrOs]t} _{, the heteropolyanion} becomes [ _XpMqOs ^]t _, and the _isopolyanion [ _MqOs ] ^t . However, the heteroatom X represents an element of the IIIB, IVB and VB groups such as B, Si, Ge, P and As, among which B, Si and P are preferred. Polyatoms M and N represent transition metals such as Ti, Zr, V, Nb, Ta, Mo and W, with Ti, Zr, V, Nb, Mo and W being preferred.
Also, p, q, r, and s represent the number of atoms, and t represents the oxidation number.
Since heteropolyanion compounds have many structures, mixed-coordination-type heteropolyanion compounds can have many more structures. Acids: H ₃ PW _x Mo _12-x O ₄₀ · nH ₂ O (phosphorus molybdic acid · n-hydrate), H _3+x PV _x Mo 12- _x O ₄₀ · nH ₂ O (phosphovanadomolybdic acid · n water hydrate), H ₄ SiW _x Mo _12-x O _{40.nH 2} O (silicotungstomolybdic acid, n-hydrate), H _4+x SiV _x Mo _12-x O _{40.nH 2} O (silicovanadomolybdic acid, n-hydrate) and the like are exemplified. (However, 1≤x≤11, n≥0)

Preferred specific examples of these heteropolyanion compounds include H ₃ PW ₃ Mo ₉ O _{40.nH 2} O, H ₃ PW ₆ Mo ₆ O _{40.nH 2} O, H ₃ PW ₉ Mo ₃ O _{40.nH 2 O , H4PV1Mo11O40.nH2O , H6PV3Mo9O40.nH2O , H4SiW3Mo9O40.nH2O , H4SiW6Mo6O40 . _ _ _ _ _ _ _ _ _ nH2O , H4SiW9Mo3O40.nH2O , H5SiV1Mo11O40.nH2O , H7SiV3Mo9O40.nH2O and other mixed coordination heteropoly _ _ _ _} Acids are exemplified. (However, n≧0)
The mixed-coordination heteropolyanion compound may be used in the form of an acid (so-called mixed-coordination heteropolyacid), or in the form of a (partial or complete) salt with a specific cation as a counterion. good too.

When the mixed-coordination heteropolyanion compound is used in the form of a salt with a specific cation as a counterion, examples of counter cation sources include alkali metals such as lithium, sodium, potassium, rubidium and cesium; magnesium, calcium, strontium, At least one selected from alkaline earth metals such as barium; metals such as manganese, iron, cobalt, nickel, copper, zinc, silver, cadmium, lead and aluminum; inorganic components such as ammonia; are mentioned. Among the inorganic components, salts of alkali metals, alkaline earth metals and ammonia are preferred.
Further, when at least one selected from these alkali metals, alkaline earth metals and ammonia is used as a counter cation source, H ₃ PW _x Mo _12-x O _{40.nH 2} O (phosphorustomolybdic acid n-hydrate), H _3+x PV _x Mo _12-x O _{40.nH 2} O (phosphovanadomolybdate n-hydrate), H ₄ SiW _x Mo _12-x O _{40.nH 2} O (silicongustomolybdate n-hydrate) ) and H _4+x SiV _x Mo _12-x O _{40.nH 2} O (silicovanadomolybdic acid.n-hydrate) in the form of a salt.

An amine compound, which is an organic component, is also preferably used as a counter cation source for the mixed-coordination type heteropolyanion compound, and a specific example thereof is preferably represented by the following general formula (5).

(R ⁸ -N(-R ¹⁰ )-) _n -R ⁹ (5)
(Wherein, R ⁸ , R ⁹ and R ¹⁰ may be the same or different, and may contain a hydrogen atom, or an ether bond, an ester bond, a hydroxyl group, a carbonyl group, or a thiol group having 1 to 30 carbon atoms. good monovalent or divalent hydrocarbon group, optionally R ⁸ and R ⁹ together form a 5- or 6-membered cycloalkyl group, or additionally a nitrogen or oxygen atom as a bridge member or optionally R ⁸ , R ⁹ and R ¹⁰ together form one or more additional nitrogen and/or oxygen atoms It may form a multi-membered multi-ring that can be included as a bridge member.R ⁸ , R ⁹ and R ¹⁰ are not hydrogen atoms at the same time.n represents an integer of 1 to 2.)

Specific examples of the amine compound that is a counter cation source for the mixed coordination heteropolyanion compound include ethylamine, propylamine, butylamine, hexylamine, octylamine, laurylamine, tridecylamine, and stearylamine. Linear primary amines; branched primary amines such as isopropylamine, isobutylamine, 2-ethylhexylamine, branched tridecylamine; dimethylamine, diethylamine, dipropylamine, dibutylamine, dihexylamine, dioctylamine, dilaurylamine , ditridecylamine, distearylamine; branched secondary amines such as diisopropylamine, diisobutylamine, di-2-ethylhexylamine, di-branched tridecylamine; N-methylbutylamine, Asymmetric secondary amines such as N-ethylbutylamine, N-ethylhexylamine, N-ethyllaurylamine, N-ethylstearylamine, N-isopropyloctylamine, N-isobutyl-2-ethylhexylamine; Linear tertiary amines such as propylamine, tributylamine, trioctylamine, trilaurylamine, tritridecylamine, tristearylamine; triisopropylamine, triisobutylamine, tri-2-ethylhexylamine, tri-branched tridecylamine branched tertiary amines such as; N,N-dimethyloctylamine, N,N-dimethyllaurylamine, N,N-dimethylstearylamine, N,N-diethyllaurylamine having mixed hydrocarbon groups such as In addition to primary amines, etc., amines having an alkenyl group such as allylamine, diallylamine, triallylamine, N,N-dimethylallylamine, alicyclic primary amines such as cyclohexylamine and 2-methylcyclohexylamine; aniline, benzylamine , 4-methylbenzylamine having an aromatic ring substituent; alicyclic secondary amines such as N,N-dicyclohexylamine and N,N-di-2-methylcyclohexylamine; dibenzylamine , N,N-di-4-methylbenzylamine, secondary amines having aromatic ring substituents; N-cyclohexyl-2-ethylhexylamine, N-cyclohexylbenzylamine, N-stearylbenzylamine, N-2 - like ethylhexylbenzylamine asymmetric secondary amines such as N,N-dimethylbenzylamine, N,N-dimethylcyclohexylamine and tricyclohexylamine; alicyclic tertiary amines such as tribenzylamine and tri-4-methylbenzylamine; Tertiary amines with aromatic ring substituents; amines having: monoethanolamine, diethanolamine, monoisopropanolamine, monopropanolamine, butanolamine, triethanolamine, N,N-dimethylethanolamine, N-methylethanolamine, N-methyldiethanolamine, N-ethylethanolamine, N-propylethanolamine, N-isopropylethanolamine, N-butylethanolamine, N-cyclohexyl-N-methylaminoethanol, N-benzyl-N-propylaminoethanol, or N-hydroxyethylpyrrolidine, N-hydroxyethylpiperazine , alkanolamines such as N-hydroxyethylmorpholine; ethylenediamine, N-methylethylenediamine, N,N'-dimethylethylenediamine, N,N,N',N'-tetramethylethylenediamine, 1,2-propanediamine, 1 ,3-propanediamine, N,N-dimethyl-1,3-propanediamine, N-cyclohexyl-1,3-propanediamine, N-decyl-1,3-propanediamine, N-isotridecyl-1,3-propane Diamines such as diamines; N,N'-dimethylpiperazine, N-methoxyphenylpiperazine, N-methylpiperidine, N-ethylpiperidine, quinuclidine, diazabicyclo[2,2,2]octane, 1,8-diazabicyclo[5 ,4,0]-7-undecene; aromatic amines such as pyridine and quinoline; or any mixture thereof.

Preferred specific examples of these amine compounds include at least one selected from linear or branched alkyl primary, secondary, or tertiary amines having 4 to 20 carbon atoms, or alkanolamines, For example butylamine, hexylamine, cyclohexylamine, octylamine, tridecylamine, stearylamine, dihexylamine, di-2-ethylhexylamine, linear or branched ditridecylamine, distearylamine, tributylamine, trioctylamine, linear or branched tridecylamine, tristearylamine, N,N-dimethylethanolamine, N-methyldiethanolamine, triethanolamine, morpholine and the like.
At least one selected from the amine compounds represented by the general formula (5), H ₃ PW _x Mo _12-x O ₄₀ ·nH ₂ O (phosphorustungstomolybdic acid·n-hydrate), and H _3+x PV _x Mo _{12 -x} O _{40.nH 2} O (phosphovanadomolybdate n-hydrate), H ₄ SiW _x Mo _12-x O _{40.nH 2} O (silicotungstomolybdate n-hydrate), H _4+x SiV _x It is more preferably used in the form of a salt with at least one selected from Mo _12-x O _{40.nH 2} O (silicovanadomolybdic acid.n-hydrate).
Among the above mixed-coordination heteropolyanion compounds, H ₃ PW _x Mo _12-x O _{40.nH 2} O (phosphorustungstomolybdic acid.n-hydrate), H _3+x PV _x Mo _12-x O _{40.nH 2} O (phosphovanadomolybdic acid n-hydrate), H ₄ SiW _x Mo _12-x O ₄₀ nH ₂ O (silicone gustomolybdic acid n-hydrate), or mixed coordination heteropolyacids of these Organic amine salts of mixed coordination heteropolyacids are most preferred.

The second coating layer other than the silicon compound-containing layer of the composite particles contained in the metal pigment composition according to the present invention further improves the corrosion resistance of the core metal particles (preferably aluminum particles or aluminum alloy particles). It may be a layer containing a corrosion inhibitor. The corrosion inhibitor to be added is not particularly limited, and any known corrosion inhibitor can be used. The amount used may be within a range that does not impair the desired effects of the present invention. Examples of such corrosion inhibitors include acidic phosphoric acid esters, dimer acids, organophosphorus compounds, metal salts of molybdic acid, and the like.

In the silicon compound-containing layer and/or the second coating layer of the composite particles contained in the metal pigment composition, or as a separate layer, from the viewpoint of adhesion and chemical resistance when forming a coating film, an organic oligomer is further added. Or it can contain a polymer.
In addition, from the viewpoint of storage stability, inorganic phosphoric acids and salts thereof, and acidic organic (sub)phosphates and It may contain at least one selected from the group consisting of salts thereof.
These compounds are not particularly limited, and for example, those disclosed in JP-A-2019-151678 can be used.

(5) In the composite particles, the ratio of the metal element content based on the metal particles to the silicon content based on the coating layer is 0.02 or more and 0.3 as a ratio of the silicon content to the metal element content. The composite particles contained in the metal pigment composition of the present invention have a metal particle as the core and one or more coating layers on the surface of the metal particle. At least one of the coating layers is a silicon compound-containing layer (so-called silica layer), as described in detail in the description of requirement (4) above. Therefore, the composite particles of the metal pigment composition according to the present invention are composed of a metal element constituting the core metal particles of the composite particles and a silicon compound-containing layer (so-called silica) constituting the coating layer on the surface of the metal particles. layer) as a constituent.
In the composite particles contained in the metal pigment composition of the present invention, the ratio of the silicon element content to the metal element content is preferably 0.02 or more and 0.3 or less. Here, the content of each element in the composite particles can be determined, for example, by dissolving the metal pigment composition and measuring the content of the metal element and the content of the silicon element in the composite particles contained therein by high frequency inductively coupled plasma. It can be analyzed and determined by (ICP) emission spectroscopy.
The content of the metal element constituting the metal particle serving as the core of the composite particle is proportional to the size of the metal particle (that is, the particle size), and the silicon compound-containing layer constituting the coating layer on the surface of the metal particle The content of silicon element from (so-called silica layer) is proportional to the thickness of the silicon compound-containing layer (so-called silica layer).
When the above ratio is 0.02 or more, the thickness of the silicon compound-containing layer (so-called silica layer) in the coating layer on the surface of the metal particle relative to the particle size of the metal particle is a thickness that can effectively exhibit corrosion resistance. . Further, when the ratio is 0.3 or less, the thickness is such that the optical performance of the metal particles can be effectively exhibited. The lower limit of the ratio is 0.02 or more, preferably 0.03 or more, and more preferably 0.04 or more. The upper limit is 0.3 or less, preferably 0.2 or less, and more preferably 0.15 or less. That is, in the composite particles of the metal pigment composition according to the present invention, the silicon compound-containing layer (so-called silica layer) and optical performance based on the characteristics of the metal particles that are the core of the composite particles (e.g., high brightness, high flip-flop feeling, excellent coating color tone due to high hiding power). can be made Specifically, by effectively exhibiting the corrosion resistance based on the silica layer, it is possible to suppress gas generation and obtain good storage stability even when used as water-based paint such as water-based metallic paint or water-based ink. It has excellent water resistance when used as a film, and by effectively exhibiting the optical performance based on the inherent properties of metal particles, it can be used for water-based metallic paints and metallic coatings, etc. An excellent paint film color tone due to brightness, high flip-flop feeling, and high hiding power can also be obtained.
In addition, together with the satisfaction of requirements (1) to (4) described above and requirement (6) described later, it further exhibits excellent coating film color tone such as high hiding power and light brightness, and further Excellent adhesion can be exhibited even when used for coating films such as metallic coating films.
The “composite particles” in the physical property requirement (5) refer to aggregates (aggregates) when a plurality of composite particles are aggregated and adhered.
As described above, the metal particles may be composed of a single metal consisting of only one metal element, or a combination of two or more metals consisting of only one metal element (i.e., two or more metals elemental metals) may also be used. For example, when the metal particles that serve as the core of the composite particles are composed of a metal consisting of one metal element, the " metal element that constitutes the metal particles " in requirement (5) refers to the one metal element For example, when the metal particles that serve as the core of the composite particles are composed of a metal consisting of two metal elements, the " metal element that constitutes the metal particles " in requirement (5) is the It refers to two kinds of metal elements. In other words, if the metal particles that form the core of the composite particles are aluminum metal particles consisting only of the aluminum element, the " metal element constituting the metal particles " of requirement (5) refers to the aluminum metal element, If the metal particles forming the core of the composite particles are metal particles composed of two metal elements, ie, an aluminum element and another metal element, the term "aluminum metal element" and "other metal element" refers to the metal element.
As described above, the metal particles in the present invention are preferably aluminum or an aluminum alloy, more preferably aluminum.
The amount of metal particles contained in the composite particles and the silicon content contained in the silicon compound-containing layer constituting the coating layer on the surface of the metal particles satisfy the above ratio (that is, this requirement (5)). There is no particular limitation as long as it is an amount that can be used.

(6) The metal pigment composition of the present invention, wherein the number ratio of the composite particles having a particle size of 0.1 µm or more and 1 µm or less is 10% or less of the total number of the composite particles in the metal pigment composition. Composite particles having a particle size of 0.1 μm or more and 1 μm or less (hereinafter also referred to as fine composite particles) account for 10% or less of the total number of composite particles contained in the substance (that is, the total number).
As described in the above requirement (4), at least one of the coating layers formed on the surface of the metal particles serving as the cores of the composite particles contained in the metal pigment composition according to the present invention is a silicon compound-containing layer (so-called silica layer ), excellent corrosion resistance can be obtained. In order to obtain excellent corrosion resistance, this silica layer has a constant thickness that satisfies the aforementioned requirement (5). However, fine composite particles having a particle size of 1 μm or less (specifically, composite particles having a particle size of less than 0.1 μm are too small to affect the performance of the present invention. Therefore, composite particles Therefore, composite particles having a particle size of 0.1 μm or more and 1 μm or less (i.e., microcomposite particles) are excluded. The thickness ratio of the silica layer is increased, and the ratio of the metal itself in the composite particles is decreased. Therefore, when the number ratio of the fine composite particles in the metal pigment composition increases, the original optical performance of the metal particles (e.g., high brightness, high flip-flop feeling, excellent coating color tone due to high hiding power) is exhibited. I can't. In addition, since the thickness of such fine composite particles is relatively large relative to the particle diameter, it becomes difficult to orient the particles, and the orientation of the metal pigment as a whole is inhibited, making it impossible to exhibit the original optical performance of the metal particles. .
In addition, since fine composite particles with a particle size of 1 μm or less hinder the adhesion between the base material and the paint, if a large amount of fine composite particles are present in the metal pigment composition, when used as a paint, the base of the paint resin will be reduced. Adhesion to the material is also likely to decrease.
However, in the metal pigment composition of the present invention, the number ratio of fine composite particles is 10% or less of the total number of composite particles in the metal pigment composition. As a result, the number of composite particles having a small particle size in the total composite particles contained in the metal pigment composition can be suppressed, so that the original optical performance of the metal particles (e.g., high brightness, high flip-flop feeling, high hiding power, etc.) ) can be demonstrated.
In addition, together with the satisfaction of the above-mentioned requirements (1) to (5), the metallic pigment composition further exhibits excellent paint film color tone due to high brightness, high flip-flop feeling, and high hiding power. Aggregation of the individual composite particles that constitute the can be obtained, good storage stability can be obtained, and excellent water resistance can be obtained when used as a coating film.
The number ratio of the fine composite particles is 10% or less, preferably 5% or less, more preferably 3% or less, relative to the total number of composite particles in the metal pigment composition, and is preferably as low as possible from the above viewpoint. .
The “composite particles” in the physical property requirement (6) refer to aggregates (aggregates) when a plurality of composite particles are aggregated and adhered.
The method for measuring the number ratio of composite particles (that is, fine composite particles) having a particle size of 0.1 μm or more and 1 μm or less is not particularly limited. Created, the coating film is photographed with a digital microscope (for example, HiROX: KH-3000) at a magnification in which the total number of particles (that is, the total number of all composite particles) is about 500 or more, and image analysis. Using software (for example, Media Cybernetics: Image-ProPLUS ver.7.0), particles having an equivalent circle diameter of 0.1 μm or more and 1 μm or less are extracted from all the particles contained therein. can be obtained by counting the number of particles with respect to the total number of particles. Here, the equivalent circle diameter is the diameter of a circle having the same area as the projected area of the particle image, and is generally called Heywood diameter. For example, even if there are irregularly shaped particles that are not circular, if the area is, for example, 78.5 nm ² (particle diameter=corresponding to the area of a circle of 10 nm), the particle diameter is regarded as 10 nm. In addition, when the particles are aggregated and adhered to each other and the boundary cannot be visually recognized, the circle equivalent diameter can be obtained from the distorted cross-sectional area of the aggregated and adhered state. If the boundary can be visually recognized at a magnification, the particle diameter (equivalent circle diameter) of each particle can be measured.
As described above, the “composite particles” in the physical property requirement (6) are ultrafine composite particles having a particle size of less than 0.1 μm (specifically, composite particles having an equivalent circle diameter of less than 0.1 μm ) are excluded from being recognized as composite particles because their size is too small to have a negligible effect on the performance of the present invention.

In addition, when the volume distribution of the composite particles is measured with a laser diffraction particle size distribution meter, the number ratio of the composite particles having a particle size of 3 times or more the D ₅₀ based on volume (hereinafter also referred to as coarse composite particles is preferably 3% or less of the total number (that is, the total number) of the composite particles in the metal pigment composition.
As a result, when it is used as a coating film, it is possible to obtain a metallic coating film with a dense feeling, and when it is used as a coating film, it is possible to suppress surface roughness.
In addition, together with the satisfaction of the above-mentioned requirements (1) to (6), the individual components constituting the metal pigment composition further exhibit excellent coating film color tone such as high hiding power and light brightness. Aggregation of the composite particles is suppressed, and gas generation can be suppressed even when used as a water-based paint such as a water-based metallic paint or water-based ink, and good storage stability can be obtained. It is excellent in water resistance when used as a coating film, and can exhibit excellent adhesion even when used in a coating film such as a metallic coating film.
The number ratio of the coarse composite particles is preferably 3% or less, more preferably 2% or less, and preferably 1% or less with respect to the total number of composite particles in the metal pigment composition. More preferred.
"Composite particles" in the physical property requirements refer to aggregates (aggregates) when multiple composite particles are aggregated and adhered.
The method for measuring the coarse composite particles is not particularly limited. It can also be obtained using a meter or the like.

The number ratio of fine composite particles and coarse composite particles contained in the metal pigment composition of the present invention is mainly determined by appropriately selecting the particle size of the metal particles to be used and the silicon compound-containing layer (and, if necessary, other In the step of coating the coating layer), the stirring time, the type of stirring device, the power/degree of stirring (type and diameter of the stirring blade, the number of rotations, the presence or absence of external stirring, etc.) can be controlled by appropriately adjusting the can be done. In particular, the number ratio of the fine composite particles contained in the metal pigment composition of the present invention is, as will be described later, a fine particle size before the step of coating the silicon compound-containing layer (and other coating layers as necessary). It is preferably controlled by removal of metal particles (grinding and classification under mild conditions) and agitation under mild conditions during the step of coating the silicon compound-containing layer (and other coating layers as required).

3. Method for producing a metallic pigment composition The metallic pigment composition according to the present invention is produced, for example, from a slurry of metal powder through processes such as grinding, washing, sieving (classification), filtration, and concentration, to form predetermined scales (flakes). form), and then coating the metal particles with a silicon compound-containing layer under stirring using a solvent containing water and/or a hydrophilic solvent. can. More specifically, the following methods may be mentioned, but are not limited thereto.

The metal pigment composition according to the present invention comprises, for example, (a) metal particles, (b) a silicon-containing raw material containing at least one organosilicon compound, (c) a solvent (water and/or a hydrophilic solvent), and optionally A step of forming a silicon compound-containing layer on the surface of the metal particles (silicon compound-containing layer forming step) by hydrolyzing/(partially) condensing the organosilicon compound in the mixed liquid containing other optional components accordingly. It can be suitably manufactured by a method. This step can be carried out under normal stirring.

(1) Pulverization, sieving (classification), and filtration steps Here, the case where aluminum particles are used as the metal particles will be described as an example.
Aluminum particles are generally produced by using atomized aluminum powder and/or aluminum foil using a method commonly used in the pigment industry, such as dry ball milling, wet ball milling, attritor method, and stamp milling, and adding a grinding aid. or in the presence of an inert solvent to form so-called scale-like (flake-like) aluminum particles, and after this process, sieving (classification) removes coarse aluminum particles, filtering, washing, A paste-like aluminum particle pigment is obtained through a necessary process such as mixing. It is also referred to herein as a "pasty aluminum flake pigment".
Here, the scale-like (flake-like) aluminum particles with a large particle size are aluminum particles that do not pass through a #300 to #800 metal mesh.

In the present invention, it is desirable to grind the atomized aluminum powder and/or the aluminum foil under mild conditions. By doing this, among the composite particles obtained by subsequently forming a coating layer containing at least one silicon compound-containing layer on the surface of the aluminum particles, composite particles with a microparticle diameter of 1 μm or less (specifically Therefore, composite particles having a particle size of less than 0.1 μm are excluded without being recognized as composite particles because the size is too small to affect the performance of the present invention. This is because the generation of composite particles having a particle size of 1 μm or less) can be effectively suppressed.

Here, mild conditions refer to appropriately adjusting and combining conditions such as reducing the mass of each grinding ball and reducing the rotational speed of the grinding device.
In addition to performing the above operation, adjusting the average particle size (D ₅₀ ) of the scale-like (flake-like) aluminum particles to the range of the present embodiment and improving productivity, grinding It is good to determine the conditions.
Considering that the average particle diameter (D ₅₀ ) of the scale-like (flake-like) aluminum particles is in the range of 3 μm or more and 30 μm or less, particularly preferable grinding conditions are as follows. Atomized aluminum powder is used, the mass of each grinding ball used in the grinding device is preferably 0.08 to 11 mg, and the rotation speed of the grinding device is 33 with respect to the critical rotation speed (Nc). % to 78%, more preferably 36% to 57%.

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 the reduction of the proportion of fine particles and increasing the surface smoothness of the aluminum particles. is more preferable, and 7 or less is even more preferable.
The specific gravity of the grinding balls is preferably higher than the specific gravity of the grinding solvent. Since the specific gravity of the grinding balls is greater than the specific gravity of the grinding solvent, the grinding balls can be prevented from floating on the solvent, sufficient shear stress can be obtained between the grinding balls, and the grinding proceeds sufficiently. There is a tendency.

As grinding balls used in the method for producing an aluminum pigment of the present embodiment, those having high surface smoothness such as steel balls, stainless steel balls, zirconia balls, glass balls, etc. are used to adjust and grind the surface smoothness of aluminum particles. This is preferable from the viewpoint of ball durability.
On the other hand, steel balls, alumina balls, etc. with low surface smoothness are not preferable from the viewpoint of adjusting the surface smoothness of the aluminum particles and the durability of the grinding balls.
For this reason, for example, in the case of steel balls, it is preferable to use ones whose surface smoothness has been enhanced by mechanical polishing and chemical polishing.

The mass of each grinding ball is preferably 0.08 to 11 mg, as described above.
By using grinding balls with a mass of 0.08 mg/piece or more, the grinding balls do not move individually but move in groups or in clusters, so the shear stress between the grinding balls decreases and grinding proceeds. It is possible to prevent the occurrence of so-called group motion.
Further, by using grinding balls having a mass of 11 mg/piece or less, it is possible to prevent excessive impact force from being applied to the aluminum powder, thereby preventing warping, distortion, cracking, and the like.

As the atomized aluminum powder to be used as a raw material, it is preferable to use a powder containing few impurities other than aluminum.
The purity of the atomized aluminum powder is preferably 99% or higher, more preferably 99.5% or higher, still more preferably 99.7% or higher.
The average particle size of the atomized aluminum powder as a raw material is preferably 2 to 25 μm.
The shape of the atomized aluminum powder used as the raw material is preferably spherical powder or teardrop-like powder. By using these, the shape of the aluminum pigment tends to be less likely to collapse during grinding. On the other hand, acicular powder and irregular-shaped powder are not preferable because the shape of the aluminum pigment tends to collapse during grinding.

It is preferable to use a grinding solvent when producing the aluminum pigment of the present embodiment with a grinding device equipped with a ball mill.
The types of grinding solvents are not limited to the following, but include, for example, conventionally used hydrocarbon solvents such as mineral spirits and solvent naphtha, alcohols, ethers, ketones, and esters. 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 with respect to the mass of aluminum in the atomized aluminum powder, it is possible to prevent warping, distortion, cracking, etc., caused by long-term grinding of the atomized aluminum powder, which is preferable. .
In addition, since the volume of the grinding solvent is 16.0 times or less with respect to the mass of aluminum in the atomized aluminum powder, the uniformity in the mill during grinding is improved, and the atomized aluminum powder acts as a grinding media. They tend to come into contact with each other efficiently, and grinding proceeds favorably.
The volume of grinding balls relative to the volume of grinding solvent (volume of grinding balls/volume of 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 balls is at least 0.5 times the volume of the grinding solvent, the homogeneity of the grinding balls in the mill during grinding is improved, and grinding tends to proceed favorably.
In addition, since 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 within a suitable range, and the layers of the balls do not become too high. It is preferable because problems of shape deterioration such as warpage, distortion, and cracking of particles due to crushing stress can be prevented, and decrease in luminance and increase in scattered light can be prevented.

When producing the aluminum pigment of the present embodiment with a grinding device equipped with a ball mill, it is preferable to use a grinding aid in addition to the grinding solvent described above.
Examples of grinding aids include fatty acids, fatty amines, fatty amides, fatty alcohols, and the like. Generally, oleic acid, stearic acid, stearylamine and the like are preferred. Examples of inert solvents include hydrophobic solvents such as mineral spirits, solvent naphtha, LAWS, HAWS, toluene and xylene, and these can be used alone or in combination. Grinding aids and inert solvents are not limited to these.
The grinding aid is preferably used in an amount of 0.2 to 30% by mass relative to the mass of the atomized aluminum powder.
The ball mill used for grinding the atomized aluminum powder preferably has a diameter of 0.6 to 2.4 mm.

By using a ball mill with a diameter of 0.6 mm or more, the layering 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 grinding tends to proceed favorably. .
In addition, by using a ball mill with a diameter of 2.4 mm or less, the layers of grinding balls do not become too high, and the problem of shape deterioration such as warping, distortion, and cracking of particles due to the weight of the balls is prevented, and brightness is improved. 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% of the critical rotation speed (Nc).
A rotation speed/critical rotation speed ratio of 33% or more is preferable because the uniformity of the aluminum slurry and ball movement in the ball mill is maintained.
In addition, since the rotation speed/critical rotation speed ratio is 78% or less, the grinding balls are prevented from being scraped up or falling under their own weight, and the impact force applied to the aluminum particles received from the grinding balls. is not too high, and the problem of shape deterioration such as grain warpage, distortion and cracks is prevented.
The aluminum pigment of the present embodiment can also be produced by a vacuum vapor deposition method in addition to the above-mentioned production method including the step of grinding the atomized aluminum powder.
As the pulverization step, pulverization by a wet ball mill method is preferable from the viewpoint of preventing dust explosion and ensuring safety.

Further, in the present invention, before forming a coating layer containing at least one silicon compound-containing layer on the surface of the scale-like (flake-like) aluminum particles, among the aluminum particles, the aluminum particles having a small particle size are classified. It is preferable to remove in advance by By doing this, among the composite particles obtained by subsequently forming a coating layer containing at least one silicon compound-containing layer on the surface of the aluminum particles, composite particles with a microparticle diameter of 1 μm or less (specifically Therefore, composite particles having a particle size of less than 0.1 μm are excluded without being recognized as composite particles because the size is too small to affect the performance of the present invention. This is because the generation of composite particles having a particle size of 1 μm or less) can be effectively suppressed. Specifically, the number ratio of composite particles having a particle size of 0.1 μm or more and 1 μm or less in the aluminum pigment can be suppressed to 10% or less of the total number of composite particles in the same aluminum pigment. By using this classification together with the above-described grinding under mild conditions, it is possible to further enhance the suppression of the generation of fine composite particles.
However, it is not always necessary to perform both the above-described grinding step under mild conditions and the above-described classification for removing the fine scale-like (flake-like) aluminum particles having a particle size. You may do only one or the other. In other words, without performing the grinding step under mild conditions as described above, only a step of removing scaly (flake-shaped) aluminum particles with a small particle size by classification after the normal grinding step may be performed, or It is also possible to perform only the above-mentioned grinding step under mild conditions without performing the subsequent classification.
As the classification step for removing scaly (flake-shaped) aluminum particles with a small particle size, wet classification is preferable from the viewpoint of ensuring safety. There are methods using machines such as hydraulic classifiers, siphon sizers, centrifugal classifiers, liquid cyclones, jet sizers, rake classifiers, Akins type machines, spiral classifiers, ball classifiers, hydro separators and decanters.

As the metal particles in the production of the metal pigment composition of the present invention, a metal layer deposited on a support material such as a resin film by physical vapor deposition (PVD) is peeled off from the support material and pulverized, so-called evaporated aluminum. Pigments can also be used. Also in this case, it is important to appropriately adjust the grinding conditions to suppress the generation of fine particles, or to remove the fine particles by classification.

(2) Step of forming a silicon compound-containing layer The above-mentioned (a) metal particles, (b) a silicon-containing raw material containing at least one organosilicon compound, and (c) a solvent, and optionally other optional components Mixtures containing can be prepared by mixing these components. The order of mixing is not particularly limited.

As the (a) metal particles, particles of aluminum or an aluminum alloy can be preferably used. As for the particle shape, scale-like (flake-like) metal particles can be suitably used as described above.

The content (solid content) of the metal particles in the mixed solution is not particularly limited as long as the metal pigment composition of the present invention can be obtained, and can be appropriately set according to the type and particle size of the metal particles used. .

An organosilicon compound is used as the silicon-containing raw material. The organosilicon compound is not limited, but preferably those mentioned above can be used.
An organosilicon compound represented by the above formula (1) (typically tetraalkoxysilane) and/or a condensate thereof, and a silane coupling agent represented by any one of the above formulas (2) to (4). At least one type can be preferably used.
Hereinafter, the case where tetraalkoxysilane is used as the organosilicon compound represented by the above formula (1) will be described as an example. In the following description, tetraalkoxysilane and/or its condensate may be collectively referred to simply as "tetraalkoxysilane".

When the tetraalkoxysilane represented by the above formula (1) and the silane coupling agent represented by any one of the above formulas (2) to (4) are used in combination, a method of using a mixture of both ("first method”) can be employed. Alternatively, a method comprising the step of subjecting the metal particles to one treatment to form a first silicon compound-containing layer and the other treatment to form a second silicon compound-containing layer (referred to as a "second method" ) can also be adopted.

As a first method, for example, a pH is appropriately adjusted to cause a hydrolysis/condensation reaction between a tetraalkoxysilane and a silane coupling agent to form a silicon compound-containing layer.

As a second method, for example, by appropriately adjusting the pH of the mixed solution containing the metal particles and the tetraalkoxysilane represented by the above formula (1), the tetraalkoxysilane is hydrolyzed/condensed to react the surface of the metal particles. A step of forming a first silicon compound-containing layer (for example, a silica coating made of amorphous silica), and metal particles and a silane coupling agent represented by any of the above formulas (2) to (4) A method including the step of forming a second silicon compound-containing layer on the surface of the first silicon compound-containing layer by hydrolyzing/condensing the silane coupling agent by adjusting the pH of the mixed solution.

The amount of the tetraalkoxysilane represented by the formula (1) or the condensate thereof to be used can be appropriately set according to the type of tetraalkoxysilane to be used. The amount used is, for example, from the viewpoint of the coating treatment effect and from the viewpoint of suppressing the aggregation of the metal particles or the deterioration of the glitter feeling, etc. It is preferably 3 parts by mass or more and 100 parts by mass or less, and even more preferably 5 parts by mass or more and 60 parts by mass or less.

The amount of the silane coupling agent represented by any of the above formulas (2) to (4) is not particularly limited, but from the viewpoint of the desired coating treatment effect, the metal particles (solid content) On the other hand, it is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 15 parts by mass, and even more preferably 1 to 10 parts by mass.

The solvent in the mixed solution, that is, the solvent for the hydrolysis reaction and/or condensation reaction of the organosilicon compound may be appropriately selected depending on the type of silicon-containing raw material to be used. An organic solvent or a mixed solvent thereof can be used. By using these solvents, the uniformity of the reaction and the uniformity of the resulting hydrolyzate and/or condensation product can be improved. In the embodiment in which the silicon compound-containing layer is formed directly on the metal particles, it is particularly preferable that the solvent of the mixture contains a hydrophilic organic solvent from the viewpoint of avoiding rapid reaction between the metal particles and water. . In the present invention, a mixed solvent of water and a hydrophilic organic solvent can be preferably used.

Examples of hydrophilic organic solvents include, but are not limited to, alcohols such as methanol, ethanol, propanol, butanol, isopropanol, and octanol; ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, Ether alcohols such as propylene glycol monoethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether and their esters; ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, polyoxyethylene glycol , polyoxypropylene glycol, ethylene propylene glycol; ethyl cellosolve, butyl cellosolve, acetone, methoxypropanol, ethoxypropanol, and other alkoxy alcohols. These can be used alone or in combination of two or more.

Moreover, when a mixed solvent of water and a hydrophilic organic solvent is used as the solvent, the ratio between the two is not particularly limited as long as the metallic pigment composition of the present invention can be obtained.

The amount of the solvent used in the step of forming the silicon compound-containing layer (excluding the amount of solvent for pre-dispersion of the metal particles) is not limited, but is usually per 100 parts by mass of the metal particles (solid content). 100 to 10,000 parts by mass, preferably 200 to 1,000 parts by mass. When the amount of the solvent used is 100 parts by mass or more, an increase in the viscosity of the mixed liquid (slurry) is suppressed, and suitable stirring becomes possible. In addition, when the amount of the solvent used is 10,000 parts by mass or less, it is possible to prevent the recovery and recycling costs of the treatment liquid from increasing. In addition, in the case of the second method, the amount of solvent used here refers to the total amount of solvent used for forming the first silicon compound-containing layer and forming the second silicon compound-containing layer.

If necessary, other additives may be added to the mixed solution as long as the effects of the present invention are not impaired. Examples thereof include catalysts such as hydrolysis catalysts and dehydration condensation catalysts, as well as surfactants and metal corrosion inhibitors.

Among these, a hydrolysis catalyst can be preferably used. By blending the hydrolysis catalyst, it is possible to adjust the pH of the mixed liquid and efficiently hydrolyze and dehydrate the organosilicon compound. As a result, the silicon compound-containing layer is efficiently formed on the surface of the metal particles It is possible to reliably form them.

A known or commercially available hydrolysis catalyst may be used, and is not particularly limited. Examples of hydrolysis catalysts include inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid; organic acids such as benzoic acid, acetic acid, chloroacetic acid, salicylic acid, oxalic acid, picric acid, phthalic acid, and malonic acid; vinylphosphonic acid. , 2-carboxyethanephosphonic acid, 2-aminoethanephosphonic acid and octanephosphonic acid. These hydrolysis catalysts may be used alone or in combination of two or more.
Examples of hydrolysis catalysts include inorganic alkalis such as ammonia, sodium hydroxide and potassium hydroxide; inorganic alkali salts such as ammonium carbonate, ammonium hydrogen carbonate, sodium carbonate and sodium hydrogen carbonate; monomethylamine, dimethylamine, Amines such as trimethylamine, monoethylamine, diethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, N,N-dimethylethanolamine, ethylenediamine, pyridine, aniline, choline, tetramethylammonium hydroxide, guanidine; ammonium formate, Organic acid salts such as ammonium acetate, monomethylamine formate, dimethylamine acetate, pyridine lactate, guanidinoacetic acid, and aniline acetate can also be used. These hydrolysis catalysts can be used alone or in combination of two or more.

The amount of the hydrolysis catalyst to be added is not particularly limited, but is usually 0.01 parts by mass or more and 20 parts by mass or less relative to 100 parts by mass of the metal particles (solid content), particularly 0.02 parts by mass or more and 10 parts by mass. It is preferable to set it as part by mass or less. When the addition amount is 0.01 parts by mass or more, a sufficient amount of the silicon compound-containing layer can be deposited. Also, when the amount added is 20 parts by mass or less, aggregation of the metal particles can be effectively suppressed.

In the preparation of the mixed liquid, it is sufficient that these components are mixed uniformly in the mixed liquid, and the mixing order is not particularly limited.
In the production of the metal pigment composition according to the present invention, it is preferable to prepare the mixed solution under moderately strong stirring.

The temperature of the mixed solution may be normal temperature or under heating. In general, the temperature of the mixed liquid should be 20°C or higher and 90°C or lower, and it is particularly preferable to control it in the range of 30°C or higher and 80°C or lower. When the temperature is 20° C. or higher, the formation speed of the silicon compound-containing layer can be increased and the treatment time can be shortened. On the other hand, when the temperature is 90° C. or lower, the reaction can be easily controlled, and the probability of obtaining desired composite particles can be increased.

The stirrer for stirring the mixed liquid is not particularly limited, and a known stirrer capable of efficiently and uniformly stirring the mixed liquid containing the aluminum particles and the organosilicon compound can be used. Specific examples include kneaders, kneaders, rotary vessel agitators, agitating reactors, V-type agitators, double cone agitators, screw mixers, sigma mixers, flash mixers, airflow agitators, ball mills, edge runners, etc. is mentioned. Further description of the agitator is provided below.

The temperature of the mixture containing the metal particles and the organosilicon compound is usually about 10 to 100°C, preferably 30°C or more and 80°C or less. When this temperature is 10° C. or higher, the reaction time for obtaining a sufficient treatment effect can be shortened. Further, when this temperature is 100° C. or less, it becomes easier to control the reaction for obtaining the desired metallic pigment composition.

The stirring time of the mixed solution is not particularly limited as long as it is sufficient for forming the desired silicon compound-containing layer. The stirring time is, for example, preferably 0.5 hours or more and 10 hours or less, more preferably 1 to 5 hours. A sufficient treatment effect can be obtained by stirring for 0.5 hours. Moreover, an increase in processing cost can be suppressed by setting the stirring time to 10 hours or less.

In the mixed solution, a silicon compound-containing layer is formed on the surface of the metal particles (or through the second coating layer) by hydrolyzing/condensing the silicon-containing raw material. This hydrolysis/condensation reaction can be carried out particularly by adjusting the pH of the mixture.

When adjusting the pH, since the pH value of the mixed solution changes particularly at the stage where the silicon compound-containing layer is formed on the surface of the metal particles (or via the second coating layer), the pH value must be within a certain range. It is desirable to make appropriate adjustments so that it can be maintained. At that time, it is desirable to adjust the pH value by adding a hydrolysis catalyst, but other acidic or alkaline compounds may be used to adjust the pH value as long as the properties of the metal pigment composition according to the present invention are not impaired. may

When a basic hydrolysis catalyst is used as the hydrolysis catalyst, the pH value is preferably 7 or more and 11 or less, more preferably 7.5 or more and 10 or less. A silicon compound-containing layer can be rapidly formed by a pH value of 7 or more. On the other hand, when the pH value is 11 or less, aggregation of metal particles and deterioration of brightness can be suppressed, and generation of hydrogen gas due to corrosion can be prevented.

When an acidic hydrolysis catalyst is used as the hydrolysis catalyst, the pH value is preferably 1.5 or more and 4 or less, more preferably 2 or more and 3 or less. When the pH value is 1.5 or higher, the reaction can be appropriately controlled, making it easier to obtain a metallic pigment composition containing desired composite particles. On the other hand, when the pH value is 4 or less, the deposition rate of the silicon compound-containing layer can be kept high.

In the case of adopting either the first method or the second method, the hydrolyzate and/or condensate of the organosilicon compound represented by the general formula (1) is a metal particle ( It is preferable to add 0.01 to 50 parts by mass, more preferably 1 to 30 parts by mass, based on 100 parts by mass of solid content) in terms of the state in which the hydrolysis and condensation reactions are completed. Further, the silane coupling agent represented by any one of the above general formulas (2) to (4), and / or hydrolyzate derived from partial condensate thereof and / or condensate thereof, metal particles (solid 0.01 to 0.8 parts by mass, more preferably 0.01 to 0.7 parts by mass, based on 100 parts by mass of hydrolysis and condensation reactions.

The amount of the hydrolyzate and/or condensate of the organosilicon compound represented by the general formula (1) to be added is the mass of the organosilicon compound represented by the general formula (1) used in the production of the metal pigment composition. is multiplied by the mass ratio before and after the reaction when all of the organosilicon compound is hydrolyzed and condensation reaction is performed.
For example, when tetraethoxysilane (TEOS) is used as the organosilicon compound represented by the general formula (1), the hydrolyzate of the organosilicon compound is obtained using the following mass ratios before and after the hydrolysis and condensation reaction. and/or the amount of the condensate to be added can be calculated.
(Hydrolysis)
Si( _OC2H5 ) _{4 (} molecular weight: 208) ₊ 4H2O
→ Si(OH) ₄ (molecular weight: 96) + (C ₂ H ₅ OH) ₄
(condensation)
Si(OH) ₄ (molecular weight: 96) + Si(OH) ₄ (molecular weight: 96)
→ (SiO ₂ ) ₂ (molecular weight: 60×2) + 4H ₂ O
Before and after the above hydrolysis and condensation reactions, the mass becomes 60/208=0.288 times. The amount of the hydrolyzate and/or its condensate added is 0.288 times that amount, ie, 2.88 parts by mass.

Similarly, the addition amount of the hydrolyzate such as the silane coupling agent represented by any one of the general formulas (2) to (4) and / or the condensate thereof is also the general formula used in the production of the metal pigment composition The silane coupling agent and/or the partial condensate thereof are all hydrolyzed to the mass of the silane coupling agent and/or the partial condensate thereof represented by any one of (2) to (4), and the condensation reaction It can be calculated by multiplying the mass ratio before and after the reaction.
For example, when methyltrimethoxysilane is used as the silane coupling agent represented by the general formula (2), the hydrolysis of the silane coupling agent is performed using the following mass ratios before and after the hydrolysis and condensation reaction. It is possible to calculate the addition amount of the product and/or its condensate.
(Hydrolysis)
_{CH3Si(OCH3)3 ( molecular} weight: 136) + _3H2O
→ CH ₃ Si(OH) ₃ (molecular weight: 94) + (CH ₃ OH) ₃
(condensation)
CH3Si(OH) ₃ (molecular weight: 94) + _CH3Si (OH) _{3 (} molecular weight: 94)
→ (SiCH ₃ O _1.5 ) ₂ (molecular weight: 67×2) + 3H ₂ O
Before and after the above hydrolysis/condensation reaction, the mass becomes 67/136=0.49 times. When used, the amount of the hydrolyzate and/or the condensate added is 0.49 times that, ie, 0.60 parts by mass.

Also, in the case of adopting either the first method or the second method, the metal particles are mixed with the organosilicon compound as the source of the silicon compound (or when forming the second coating layer). (before combining with the molybdenum compound), it is preferably sufficiently dispersed in water, a hydrophilic organic solvent, or a mixed solvent thereof. In this pre-dispersion (initial dispersion), preferably, part of the dispersion (for example, 0.5% by mass or more and 30% by mass or less, preferably 1% by mass or more and 20% by mass or less, per minute of the entire dispersion, More preferably, 1% by mass or more and 15% by mass or less) is extracted from the dispersing tank and then returned to the dispersing tank. Dispersibility can be further enhanced by performing ultrasonic treatment outside the dispersing tank in the middle of the external circulation flow path.
Although the ultrasonic treatment is not particularly limited, it can be usually performed at 10 W or more and 1000 W or less, preferably 50 or more and 800 W or less, and usually 20 seconds or more and 10 minutes or less, preferably about 30 seconds to 5 minutes. In addition, the amount of the solvent used for this pre-dispersion is usually about 100 to 10000 parts by mass with respect to 100 parts by mass of the metal particles (solid content) from the viewpoint of appropriately adjusting the strength of stirring to obtain sufficient dispersion. It is preferably 200 parts by mass or more and 5000 parts by mass or less, and more preferably 300 parts by mass or more and 1000 parts by mass or less.
Such pre-dispersion of the metal particles can be carried out usually at 10° C. or higher and 80° C. or lower, preferably 15° C. or higher and 60° C. or lower, most preferably around room temperature (about 20 to 30° C.). Also, the pre-dispersion of the metal particles (including ultrasonic treatment, if any) can be carried out for a period of 5 minutes to 10 hours, preferably 10 minutes to 5 hours.

(3) Step of Forming Second Coating Layer As described above, the second coating layer (if formed) is preferably formed particularly between the metal particles and the silicon compound-containing layer. Therefore, a layer structure of "metal particles/second coating layer/silicon compound-containing layer" can be preferably adopted.
The second coating layer is not particularly limited, but may be a molybdenum-containing coating, a phosphate compound coating, or the like. Preferred examples of the molybdenum-containing material constituting the molybdenum-containing coating include the mixed coordination heteropolyanion compound disclosed in JP-A-2019-151678. Examples of constituents of the second coating layer, including mixed-coordination heteropolyanion compounds, are described above.
Hereinafter, an embodiment in which a molybdenum-containing film is formed as the second coating layer between the metal particles and the silicon compound-containing layer will be described as an example.

When forming a molybdenum-containing coating as a second coating layer between the metal particles and the silicon compound-containing layer, prior to the formation of the silicon compound-containing layer, the metal particles and the molybdenum compound (typically mixed coordination heteropolyanion compound), a molybdenum-containing coating can be formed on the surface of the metal particles.

The method for forming the molybdenum-containing coating on the surface of the metal particles is not particularly limited, and any method may be used as long as the mixed liquid containing the metal particles and the molybdenum compound in the aqueous solvent can be uniformly stirred. For example, a molybdenum-containing coating can be formed on the surface of the metal particles by stirring or kneading a mixture containing metal particles and a molybdenum compound in a slurry or paste state. The molybdenum compound may be dissolved or dispersed in the mixture.

Further, the stirrer for stirring the mixed liquid containing the metal particles and the molybdenum compound is not particularly limited, and a known stirrer capable of efficiently and uniformly stirring the mixed liquid containing the aluminum particles and the molybdenum compound is used. machine can be used. Specific examples include kneaders, kneaders, rotary vessel agitators, agitating reactors, V-type agitators, double cone agitators, screw mixers, sigma mixers, flash mixers, airflow agitators, ball mills, edge runners, etc. is mentioned. Examples of the stirring blades of the stirrer are not particularly limited, but anchor blades, paddle blades, propeller blades, turbine blades and the like can be mentioned.

The amount of the molybdenum compound used can be appropriately set according to the type of molybdenum compound used. The amount used is generally 0.02 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the metal particles (solid content), and particularly 0.1 parts by mass or more and 10 parts by mass or less. is preferred. When the content is 0.02 parts by mass or more, a sufficient treatment effect can be obtained. Moreover, when the content is 20 parts by mass or less, the resulting metallic pigment composition can maintain high luster.

As a solvent used for mixing the metal particles and the molybdenum compound, water, a hydrophilic organic solvent, or a mixed solvent thereof can usually be used.

Examples of hydrophilic organic solvents include alcohols such as methanol, ethanol, propanol, butanol, isopropanol, octanol; ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monoethyl ether. , propylene glycol monomethyl ether, dipropylene glycol monomethyl ether and other ether alcohols and their esters; ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, polyoxyethylene glycol, polyoxypropylene glycol , ethylene propylene glycol; ethyl cellosolve, butyl cellosolve, acetone, methoxypropanol, ethoxypropanol, and other alkoxy alcohols. These can use 1 type(s) or 2 or more types.

The amount of solvent used in the step of forming the second coating layer (excluding the amount of solvent for pre-dispersion of metal particles) is not particularly limited, but usually metal particles (solid content) per 100 parts by mass It is preferably 50 parts by mass or more and 5000 parts by mass or less, more preferably 100 parts by mass or more and 2000 parts by mass or less. When the amount of the solvent used is 50 parts by mass or more, uneven distribution of the molybdenum compound and aggregation of the metal particles can be suppressed. Further, when the amount of the solvent used is 5000 parts by mass or less, a sufficient effect of treating the metal particles with the molybdenum compound can be obtained.

The temperature of the mixed liquid when stirring the mixed liquid containing the metal particles and the molybdenum compound is usually about 10 to 100°C, preferably 30°C or higher and 80°C or lower. When this temperature is 10° C. or higher, the reaction time for obtaining a sufficient treatment effect can be shortened. Further, when this temperature is 100° C. or less, it becomes easier to control the reaction for obtaining the desired metal pigment composition.

The stirring time of the mixed solution is not particularly limited as long as it is sufficient for forming the desired molybdenum-containing coating. The stirring time is, for example, preferably 0.5 hours or more and 10 hours or less, more preferably 1 hour or more and 5 hours or less. A sufficient treatment effect can be obtained by stirring for 0.5 hours. Moreover, an increase in processing cost can be suppressed by setting the stirring time to 10 hours or less.

After the mixture containing the metal particles and the molybdenum compound has been stirred, the particles having the second coating layer formed thereon can be collected. In this case, well-known washing, solid-liquid separation, etc. can be appropriately carried out as necessary. For example, it is preferable to remove water and unreacted substances from the cake containing the metal particles having the molybdenum-containing coating by washing the mixture with a hydrophilic solvent and then filtering it with a filter or the like. In this manner, a molybdenum-containing coating, which is the second coating layer, can be formed. Also when forming other 2nd coating layers, it can implement according to said method.

In the embodiment in which the second coating layer (molybdenum-containing coating) and then the silicon compound-containing layer are formed on the metal particles, the second coating layer is formed after stirring the mixed liquid containing the metal particles and the molybdenum compound. Without recovering the particles, a silicon compound source (typically, an organosilicon compound represented by the above formula (1), such as tetraalkoxysilane and/or a condensate thereof, and the above formula ( At least one of the silane coupling agents represented by any one of 2) to (4) may be directly added and stirred in water and/or a hydrophilic organic solvent dispersion. At this time, an organosilicon compound represented by the above formula (1), such as a tetraalkoxysilane and/or a condensate dispersion thereof, is added to the system containing the particles on which the second coating layer is formed, and then the above A dispersion of at least one of the silane coupling agents represented by any of formulas (2) to (4) may be added and stirred (the second method in the above-mentioned "silicon compound-containing layer forming step" ).

(4) Stirring Conditions In the production of the metal pigment composition according to the present invention, at least the step of forming the silicon compound-containing layer must be carried out under stirring. Moreover, in the production of the metal pigment composition according to the present invention, it is preferable to carry out not only the step of forming the silicon compound-containing layer but also the step of forming the second coating layer under stirring. In the embodiment in which the metal particles are pre-dispersed as described above, this is also preferably carried out under stirring. Further, in the production of the metal pigment composition according to the present invention, it is further preferable to carry out all the steps including pre-dispersion of the metal particles, the step of forming the second coating layer, and the step of forming the silicon compound-containing layer under stirring. preferable.
In the production of the metal pigment composition according to the present invention, at least the step of forming the silicon compound-containing layer is carried out under appropriately controlled stirring, whereby the composite particles adhere to each other through the silicon compound-containing layer, or the metal It is possible to effectively suppress or prevent a phenomenon in which aggregated particles of particles are coated with a silicon compound-containing layer. In addition, the entire process, including the pre-dispersion of the metal particles, the step of forming the second coating layer, and the step of forming the silicon compound-containing layer (until the formation of all the layers to be formed on the surfaces of the metal particles is completed), was carried out under stirring. By doing so, it becomes possible to more easily obtain the metal pigment composition according to the present invention that satisfies all of the physical property requirements (1) to (6) above.
The following description of stirring conditions can apply to any step in the production of the metallic pigment composition according to the present invention.

Stirring can be carried out with a known or commercially available stirring device. For example, at least one of kneader, kneader, rotary vessel agitator, agitating reactor, V-type agitator, double cone agitator, screw mixer, sigma mixer, flash mixer, airflow agitator, ball mill, edge runner, etc. one can be used.

Stirring is preferably carried out under particularly mild conditions.
The term "mild conditions" as used herein means that the step of forming the silicon compound-containing layer is performed by stirring at a low speed with a tip speed of the stirring blade of 0.5 m/sec or more and 20 m/sec or less.
Among the composite particles obtained by forming a coating layer containing at least one silicon compound-containing layer on the surface of the metal particles by performing such low-speed stirring, composite particles having a small particle size (specifically, Since composite particles having a particle size of less than 0.1 μm are too small to affect the performance of the present invention, they are not considered as composite particles. This is because it is possible to effectively suppress the generation of the composite particles having Specifically, the number ratio of composite particles having a particle size of 0.1 μm or more and 1 μm or less in the metallic pigment composition is suppressed to 10% or less of the total number of composite particles in the metallic pigment composition. can be done. Stirring under this mild condition can more effectively reduce the ratio of composite particles with fine particle diameters by using it in combination with the grinding and classification under mild conditions described above.

Among the above stirrers, it is preferable to use a stirring tank type device that stirs with stirring blades. The stirring blade exerts a pressure shearing action as well as a circulating action for fluidizing the entire reaction system including the liquid phase, and as a result, it is possible to more effectively suppress the formation of agglomeration of the composite particles.

The shape of the stirring blade is not particularly limited, and for example, anchor type, propeller type, turbine type, inclined turbine type, fan turbine type, paddle type, inclined paddle type, and gate type can be used. Maxblend blades (manufactured by Sumitomo Heavy Industries Process Equipment Co., Ltd.) and full zone blades (manufactured by Shinko Environmental Solutions Co., Ltd.) are also suitable. Moreover, the stirring blades having these shapes can be combined in multiple stages.

The stirring speed is preferably such that the stirring impeller is not exposed by the vortex generated by the stirring. Also, in order to suppress the vortex caused by stirring, a cylindrical tank, a rectangular tank, or a tank provided with a baffle plate can be preferably used.

In the production of the metal pigment composition containing the composite particles according to the present invention, the optimum size of the stirring tank and stirring blades and the speed of the stirring blades are set in relation to the amount of the mixed liquid and the physical properties (density, viscosity, etc.). is desirable. The size of the stirring tank should be selected so that the maximum amount of the liquid mixture used in a series of steps is 20% or more and 80% or less of the stirring tank. In the case of a cylindrical stirring tank, the ratio of the height (L) to the inner diameter (D) of the stirring tank is generally in the range of 0.5 or more and 3.0 or less. The range is 2 or less. In addition, the maximum diameter of the stirring blade is generally in the range of 0.2 or more and 0.9 or less of the inner diameter of the stirring vessel, and is preferably about 0.4 or more and 0.6 or less. . The shape (including length) of the stirring blades is desirably selected appropriately according to the physical properties of the mixed liquid, and it is important that the entire stirring tank is stirred throughout the entire process. In particular, in order to prevent unstirred stagnant areas near the liquid surface and the bottom of the agitation tank, the inclined paddle type, inclined turbine type, and propeller type, which tend to generate upstream and downstream, are combined in multiple stages, and Maxblend impeller and full zone impeller are used It is preferable to At this time, it is desirable that the distance between the stirring blade and the inner surface of the stirring vessel (including the baffle plate) is 5 mm or more. By doing so, it becomes easy to suppress breakage and deformation of the metal particles.

The speed of the stirring blade is preferably 0.5 m/s or more and 20 m/s or less at the tip, more preferably 1 m/s or more and 15 m/s or less, and 2 m/s or more and 10 m/s or less. is more preferred. When the speed of the tip of the stirring blade is in the range of 0.5 m/s or more and 20 m/s or less, the dispersibility of the composite particles in the metal pigment composition to be produced can be enhanced, and thus the individual particles can be separated. It becomes easier to obtain a metal pigment composition that has less agglomeration, excellent hiding power and color tone, and less gas generation. In addition, when the linear speed of stirring is within the above range, damage to the metal particles (for example, scale-like aluminum powder) is prevented, and the speed of the hydrolysis/condensation reaction is appropriately controlled, resulting in aggregation of the composite particles. can be effectively suppressed.

(5) Composite Particle Recovery Step After the step of forming the silicon compound-containing layer (and optionally the second coating layer) on the metal particles, the resulting composite particles can be recovered. Upon recovery, known treatments such as washing and solid-liquid separation can be carried out as necessary. For example, it is preferable to remove water and unreacted substances from the composite particle-containing cake by washing the dispersion with an organic solvent and then filtering it with a filter. Moreover, after that, if necessary, the cake containing the composite particles may be heat-treated, for example, at a temperature in the range of 100 to 500°C. The composite particles recovered in this manner can constitute a metal pigment composition in which a solvent, including a small amount of water/hydrophilic solvent used in the manufacturing process, remains and is entrained, as will be described later.

4. Metallic Pigment Composition The metallic pigment composition of the present invention obtained as described above comprises composite particles containing metal particles and one or more coating layers on the surface thereof, and solid content (nonvolatile content) As a residue of the metal pigment composition containing the solvent such as water/hydrophilic solvent used in the manufacturing process.
The metal pigment composition usually contains an organosilicon compound (for example, at least one of the organosilicon compounds represented by the general formula (1) and any one of the general formulas (2), (3) and (4) At least one selected from silane coupling agents represented by and partial condensates thereof) hydrolyzate and / or a silicon compound that is a condensate thereof is hydrolyzed / condensed with respect to 100 parts by mass of metal particles It can be present in an amount of 0.02 to 50 parts by mass calculated as the reaction is completed.
The metal pigment composition includes an optional second coating layer-forming compound (in an optional embodiment forming a molybdenum-containing coating as the second coating layer, a molybdenum-containing compound such as a mixed-coordination heteropolyanion compound ) can be present from 0.01 to 10 parts by weight relative to 100 parts by weight of the metal particles.
An optional organic oligomer or polymer may be present in the metal pigment composition from 0.01 to 50 parts by weight per 100 parts by weight of the metal particles.
In the metal pigment composition, at least one selected from the group consisting of optional inorganic phosphoric acids and salts thereof, and acidic organic (sub)phosphates and salts thereof is added to 100 parts by mass of the metal particles, 0.01 to 20 parts by weight may be present.
The metal pigment composition may contain a solvent including water/hydrophilic solvent used in the manufacturing process as a residue of the above components (non-volatile matter). The amount of solvent including water/hydrophilic solvent may be, for example, 0.5% or more and 95% or less by weight of the metal pigment composition. Alternatively, the amount of the solvent containing water/hydrophilic solvent is 1% by mass or more and 90% by mass or less, or 2% by mass or more and 80% by mass or less, or 5% by mass or more and 70% by mass or less of the metal pigment composition. good.

The metallic pigment composition may optionally contain optional components other than those described above. Examples of optional components include at least one of antioxidants, light stabilizers, polymerization inhibitors, and surfactants.

Antioxidants that can be used include phenol compounds, phosphorus compounds, and sulfur compounds.

As the light stabilizer, those used as the antioxidants described above can also be used, and benzotriazole-based compounds, benzophenone-based compounds, salicylate-based compounds, cyanoacrylate-based compounds, oxalic acid derivatives, hindered amine-based compounds (HALS), Those typified by hindered phenolic compounds can be used.

5. Uses of the Metallic Pigment Composition Such a metal pigment composition can be used for water-based paints, inks and the like. Further, this metallic pigment composition can be added to a water-based paint or water-based ink in which a resin, which is a coating film-forming component (binder), is dissolved or dispersed in a medium containing water as a main component, thereby forming a metallic water-based paint or a metallic pigment composition. It can be water-based ink. The metal pigment composition can also be kneaded with a resin or the like and used as a water-resistant binder or filler. Antioxidants, light stabilizers, and surfactants may be added when the metallic pigment composition is blended into water-based paints, water-based inks, resins, or the like.

When the metal pigment composition is used for paint or ink, it may be added to the (aqueous) paint or (aqueous) ink as it is, but it is preferable to disperse it in a solvent before adding it. Solvents to be used include water, texanol, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, and the like. Examples of these resins include acrylic resins, polyester resins, polyether resins, epoxy resins, fluororesins, rosin resins and the like. Further, examples of binders for paints or inks include rubbers in addition to resins.
These resins are preferably emulsified, dispersed or dissolved in water. Therefore, carboxyl groups, sulfone groups, etc. contained in resins can be neutralized.

Preferred resins are acrylic resins and polyester resins.
Resins such as melamine-based curing agents, isocyanate-based curing agents, and urethane dispersions can be used in combination as necessary. In addition, inorganic pigments, organic pigments, coloring pigments such as extender pigments, silane coupling agents, titanium coupling agents, dispersing agents, anti-settling agents, leveling agents, thickeners, anti-foaming agents, which are generally added to paints It may be combined with an agent. In order to improve the dispersibility in the paint, a surfactant may be added, and in order to improve the storage stability of the paint, an antioxidant, a light stabilizer, and a polymerization inhibitor may be added. may

Examples of coloring pigments include phthalocyanine, quinacridone, isoindolinone, perylene, azo lake, iron oxide, chrome, carbon black, titanium oxide, pearl mica, and the like.

The content of the metallic pigment composition according to the present invention in the water-based paint or water-based ink (resin composition) is not particularly limited, but is usually 0.1% by mass or more and 50% by mass or less. It is preferable to make it 1 mass % or more and 30 mass % or less. When this content is 0.1% by mass or more, a high decorative (metallic) effect can be obtained. In addition, when the content is 50% by mass or less, it is possible to prevent the properties of the water-based paint or water-based ink, such as weather resistance, corrosion resistance, and mechanical strength, from being impaired.

The solvent content is not particularly limited, but may be 20% by mass or more and 200% by mass or less with respect to the binder content. When the content of the solvent is within this range, the viscosity of the paint or ink can be adjusted within an appropriate range, and handling and film formation can be facilitated.

There are no particular restrictions on the method of coating with a water-based paint or the like, or the method of printing. For example, various coating methods or printing methods can be appropriately employed in consideration of the form of the water-based paint, the surface shape of the material to be coated, and the like. The coating method includes, for example, a spray method, a roll coater method, a brush coating method, a doctor blade method and the like. Examples of printing methods include gravure printing and screen printing.

A coating film formed of a water-based paint or the like may be formed on an undercoat layer or an intermediate coat layer formed by electrodeposition coating or the like. If necessary, a topcoat layer or the like may be formed on the coating film formed by a water-based paint or the like.

In the case of these layer structures, each coating film layer may be coated, and the next coating film layer may be coated after curing or drying. Subsequent coating layers may be applied without drying. The water-based paint containing the metallic pigment composition according to the present invention provides a coating film having good mirror-like luster. It is preferable to employ a method including a step of forming a coating film layer.
The curing method of the coating composition in each coating layer may be heat curing or normal temperature curing. Moreover, the drying method of the coating composition of each coating film layer may be, for example, using hot air or natural drying at room temperature.

Although the thickness of the coating film layer made of water-based paint or the like is not particularly limited, it is usually preferably 0.5 μm or more and 100 μm or less. When the thickness of the coating film layer is 0.5 μm or more, the effect of hiding the substrate by the ink or paint can be sufficiently obtained. In addition, when the thickness of the coating film layer is 100 μm or less, drying becomes easy, and the occurrence of defects such as popping and sagging can be suppressed.

The present invention will be described in greater detail below with reference to examples, but it should be noted that these examples are merely illustrative and the present invention is not limited by the description of these examples.

1. Evaluation Methods for Various Physical Properties Used in Examples and Comparative Examples Evaluation methods for various physical properties used in Examples and Comparative Examples are as follows.
(1) Measurement of average particle size _D50
Using the aluminum pigment composition obtained in each example and comparative example as a sample, the volume-based _D50 of the composite particles contained therein was measured with a laser diffraction particle size distribution analyzer "LA-300" (manufactured by HORIBA, Ltd.). was measured using
Mineral spirits were used as the measuring solvent.
For the metal pigment composition containing the composite particles to be the sample, after performing ultrasonic dispersion for 2 minutes as a pretreatment, it was put into the dispersion tank and after confirming that the appropriate concentration was reached, D ₅₀ was measured.

(2) Measurement of the ratio of Si element to Al element Measured by spectrophotometry.

(3) Measurement of number ratio of composite particles The number of composite particles (coarse composite particles) having a particle size of 3 times or more the volume-based _D50 is obtained by preparing a metallic paint to create a coating film, and the number of composite particles contained in the coating film Measured by counting. Specifically, it is as follows.
First, a metallic paint having the following components was prepared.
Aluminum pigment composition: 0.25 g as non-volatile matter
Isopropyl alcohol: 18.0 g
Acrylic resin (*1): 24g
Melamine resin (*2): 5g
*1: Acrylic 47712 manufactured by DIC Corporation
*2: Amidia J-820-60 manufactured by DIC Corporation
As the aluminum pigment composition, the one obtained in each example and comparative example was used.
In order to prepare a test piece for observation, first, the metallic paint prepared according to the above formulation was applied onto a polyethylene terephthalate film (PET film) with a 1 mil applicator, allowed to stand at room temperature for 20 minutes, and then heated at 140°C. A coated plate was prepared by baking for 20 minutes.
Next, the coating film of the prepared coated plate was photographed at a magnification of 700 using a microscope (manufactured by HiROX: KH-3000), and image analysis software (manufactured by Media Cybernetics: Image-ProPLUS ver.7.0). Using, particles with an equivalent circle diameter of 0.1 μm or more and 1 μm or less, and composite particles whose equivalent circle diameter is measured using the laser diffraction particle size distribution analyzer “LA-300” (manufactured by Horiba, Ltd.) Particles exceeding 3 times the volume-based _D50 were extracted and each counted as the number of all particles. The former is the number ratio (%) of the composite particles having a particle size of 0.1 μm or more and 1 μm or less, and the latter is the volume-based D when the volume distribution of the composite particles is measured with a laser diffraction particle size distribution meter. The number ratio (%) of composite particles having a particle size of 3 times or more of ₅₀ was used.
The imaging range was appropriately selected so that the number of particles was about 500.
Particles with an equivalent circle diameter of less than 0.1 μm were excluded because they were so small that their influence on the performance of the present invention was negligible.

2. Production of aluminum pigment composition
Reference example 1
A ball mill with an inner diameter of 2 m and a length of 30 cm was filled with a mixture of 50 kg of raw material atomized aluminum powder (average particle size: 25 μm), 82.2 kg of mineral spirit, and 1.5 kg of oleic acid, and the diameter was 1.6 mm. , with 900 kg of steel balls having a specific gravity of 7.8.
The steel balls used had a surface roughness Ra (maximum) of 0.08 μm (grade G40) or less according to JIS B 1501 for steel balls for ball bearings. The rotation speed of the ball mill was 27 rpm, and grinding was performed for 6 hours.
After grinding, the slurry in the mill was washed out with mineral spirits and passed through a 400-mesh vibrating sieve. Aluminum pigment was removed to 2%.
The obtained slurry was filtered with a filter, concentrated, recovered as an aluminum pigment cake, and the non-volatile content was adjusted to obtain an aluminum pigment paste (that is, pasty aluminum flake pigment) having a non-volatile content of 80% by mass.

Reference example 2
An aluminum pigment paste having a non-volatile content of 80% by mass was obtained in the same manner as in Reference Example 1, except that atomized aluminum powder (average particle size: 20 μm) was used as the raw material.

Reference example 3
The same operation as in Reference Example 1 was performed except that the aluminum pigment in the fine particles was removed to 9% using a liquid cyclone classifier (Murata Industries, Ltd., Model T-10 Superclone), and the nonvolatile content was 80% by mass. An aluminum pigment paste was obtained.
Example 1
Obtained in Reference Example 1 in a reaction tank having a diameter of 1 m and an internal volume of 1 m ² , having two inclined paddle-type stirring blades with a blade diameter of 0.5 m and positioned 0.3 m and 0.6 m from the bottom, respectively. 465 kg of methoxypropanol (hereinafter also referred to as “PM”) was added to 135 kg of aluminum pigment paste (average particle size 16 μm, non-volatile content 80% by mass), and the mixture was stirred at 100 rpm (the tip speed of the stirring blade was 2.6 m / sec). The aluminum paste was uniformly dispersed in the PM while stirring with a stirring blade at , and performing external circulation of returning 40 L/min of the dispersion extracted from the bottom to the reaction tank from the top of the reaction tank. In the external circulation, an ultrasonic wave with a frequency of 20 kHz and an output of 500 W was applied for 1 minute in the middle of the flow channel to improve the dispersibility of the particles.
Next, a solution obtained by dissolving 1 kg of phosphortungstomolybdic acid (H ₃ PW ₆ Mo ₆ O ₄₀ ) hydrate in 5 kg of methoxypropanol was gradually added, and the slurry was kept at 40° C. under the same conditions as above for 1 hour. Stirred.
After that, 10 kg of tetraethoxysilane was added as an organosilicon compound, and then 10 kg of 25% aqueous ammonia and 200 kg of purified water were added over 3 hours. After that, 1.3 kg of methyltrimethoxysilane was added as a silane coupling agent, and the mixture was stirred for 2 hours under the same conditions as above. After completion of the reaction, the slurry was filtered after cooling.
As a result, an aluminum pigment composition having a non-volatile content of 60% was obtained, which contained composite particles having aluminum metal particles and a coating layer containing a silicon compound-containing layer on the surface thereof. During the reaction, external circulation was continued while applying ultrasonic waves.

Example 2
The procedure was carried out in the same manner as in Example 1, except that the aluminum pigment paste obtained in Reference Example 2 (average particle size: 20 μm, non-volatile content: 80% by mass) was used. An aluminum pigment composition with a non-volatile content of 60% containing composite particles with layers was obtained.

Example 3
The procedure of Example 1 was repeated except that 3 kg of tetraethoxysilane, 3 kg of 25% aqueous ammonia, 70 kg of purified water, and 0.5 kg of methyltrimethoxysilane were used, and metal particles of aluminum and silicon compounds contained on their surfaces were prepared. An aluminum pigment composition with a non-volatile content of 60% was obtained comprising composite particles having a coating layer comprising a layer.

Example 4
Same as Example 1 except that tetraethoxysilane was changed to 50 kg, 25% aqueous ammonia to 50 kg, purified water to 500 kg, and methyltrimethoxysilane to 6.5 kg, and the addition time of ammonia water and purified water was changed to 5 hours. to obtain an aluminum pigment composition having a non-volatile content of 60%, containing composite particles having aluminum metal particles and a coating layer containing a silicon compound-containing layer on the surface thereof.

Example 5
The procedure was carried out in the same manner as in Example 1 except that the aluminum pigment paste obtained in Reference Example 3 (average particle size 20 μm, non-volatile content 80% by mass) was used, and a coating containing aluminum metal particles and a silicon compound-containing layer on the surface thereof. An aluminum pigment composition with a non-volatile content of 60% containing composite particles with layers was obtained.

Comparative example 1
An aluminum pigment composition having a non-volatile content of 60% was obtained in the same manner as in Example 1, except that the reaction with the organosilicon compound and the silane coupling agent was not carried out.

Comparative example 2
An aluminum pigment composition having a non-volatile content of 60% was obtained in the same manner as in Example 1, except that fine particles were not removed using a liquid cyclone classifier.

Comparative example 3
One inclined paddle-type stirring blade with a blade diameter of 0.35 m was placed at a position of 0.3 m from the bottom, the rotation speed was 1500 rpm, and the operation was performed in the same manner as in Example 1 except that external circulation was not performed. A 60% aluminum pigment composition was obtained.

Comparative example 4
The procedure of Example 1 was repeated except that 1.5 kg of tetraethoxysilane, 1.5 kg of 25% aqueous ammonia, 35 kg of purified water, and 0.25 kg of methyltrimethoxysilane were used, and an aluminum pigment having a nonvolatile content of 60% was prepared. A composition was obtained.

Comparative example 5
The procedure was carried out in the same manner as in Example 1 except that 100 kg of tetraethoxysilane, 100 kg of 25% aqueous ammonia, 1000 kg of purified water, and 13 kg of methyltrimethoxysilane were used, and the addition time of aqueous ammonia and purified water was changed to 7 hours. , an aluminum pigment composition having a non-volatile content of 60% was obtained.

Table 1 summarizes the compositions and manufacturing conditions of the above Examples and Comparative Examples.
Further, using the aluminum pigment compositions obtained in the above Examples and Comparative Examples, the following paints were prepared and evaluated as paints by the following methods. Those results are also shown in Table 1.

3. Preparation of paints and coatings
(1) Preparation of Paint A water-based metallic paint having the following components was prepared.
· Aluminum pigment composition: 12.0 g as non-volatile matter
・Methoxypropanol: 18.0 g
- Polyoxyethylene lauryl ether (nonionic surfactant, manufactured by Matsumoto Yushi Seiyaku Co., Ltd., trade name "Actinol L5"): 6.0 g
・ Purified water: 12.0 g
・Water-soluble acrylic resin (*1): 110.0 g
・Melamine resin (*2): 18.0g
*1: Almatex WA911, manufactured by Mitsui Chemicals, Inc.
*2: Cymel 350 manufactured by Nippon Cytec Industries Co., Ltd.
As the aluminum pigment composition, the one obtained in each example and comparative example was used.
After mixing the above components, the pH was adjusted to 7.7 to 7.8 with dimethylethanolamine, and the viscosity was adjusted from 650 to 750 mPa s (B-type viscometer, No. 3 low viscosity) with a carboxylic acid thickener and purified water. , 60 rpm, measured at 25° C.). Thus, a water-based metallic paint was prepared and used for evaluation.
(2) Preparation of coating film
The water-based metallic paint prepared according to the above formulation is air-sprayed onto a 12 cm x 6 cm intermediate coated steel plate so that the dry film thickness is 4 μm, pre-dried at 90 ° C. for 10 minutes, and then the organic solvent type top. The coating material was air-sprayed to a dry film thickness of 20 μm and dried at 140° C. for 30 minutes to prepare a coated plate, which was used as a coating film for evaluation.

4. Evaluation method
(1) Evaluation 1 (paint stability)
After the water-based metallic paint for evaluation prepared according to the above formulation was left at 23° C. for 24 hours, the change in state was visually observed and evaluated as follows.
◯: No particular change is observed.
Δ: Some aggregation of the aluminum pigment is observed.
x: Aggregation of aluminum pigment is observed.

(2) Evaluation 2 (storage stability (gas generation) evaluation)
200 g of the water-based metallic paint prepared according to the above recipe was collected in a flask, and the cumulative amount of hydrogen gas generated was observed for up to 24 hours in a constant temperature water bath at 60°C. The amount of gas generated was evaluated as follows and used as an indicator of the storage stability of the paint.
○: Less than 5 ml △: 5 ml or more and less than 20 ml ×: 20 ml or more

(3) Evaluation 3 (paint film color tone evaluation)
Using the coating film for evaluation described above, luminance, flip-flop feeling (FF), and hiding property were evaluated.
The organic solvent type top coat paint was prepared by mixing the following components and dispersing them with a spatula for 3 to 4 minutes, followed by Ford Cup No. 4 by adjusting the paint viscosity to 20.0 seconds.
・A345 (manufactured by DIC, acrylic clear resin) 420 g
・ L-117-60 (manufactured by DIC, melamine resin) 165 g
・ Solvesso 100 (manufactured by Exxon Chemical Co., Ltd., aromatic solvent) 228 g

Luminance Luminance of the coating film was evaluated using a laser type metallic feeling measuring device Alcorp LMR-200 manufactured by Kansai Paint Co., Ltd. As optical conditions, it has a laser light source with an incident angle of 45 degrees and a light receiver at light receiving angles of 0 degrees and -35 degrees. As a measurement value, the IV value was obtained at an acceptance angle of -35 degrees at which the maximum light intensity was obtained, excluding the light in the specular reflection area reflected on the coating film surface among the laser reflected light. The IV value is a parameter proportional to the intensity of specularly reflected light from the coating film, and represents the magnitude of light brightness. The determination method is as follows.
○: The width of decrease from the reference (Comparative Example 1) was less than 40.
Δ: The range of decrease from the reference (Comparative Example 1) was 40 or more.
x: The width of decrease from the reference (Comparative Example 1) was 40 or more.

・ Flip-flop feeling (FF)
It was evaluated using a gonio-colorimeter manufactured by Suga Test Instruments Co., Ltd. The FF value was obtained from the slope of the logarithm of the reflected light intensity (L value) at observation angles (light receiving angles) of 30 degrees and 80 degrees with respect to a light source with an incident angle of 45 degrees. The FF value is a parameter that is proportional to the degree of orientation of the metal pigment, and represents the size of the flip-flop feeling of the pigment. The determination method is as follows.
○: 0.05 or more higher than the standard (Comparative Example 1) △: Difference from the standard (Comparative Example 1) is less than ± 0.05 ×: 0.05 or more lower than the standard (Comparative Example 1)

・A water-based metallic paint prepared for hiding properties was applied to a polyethylene terephthalate sheet (PET sheet) with a 2 mil applicator so that the dry film thickness was 15 μm, and the coating was dried at 140 ° C for 30 minutes. Judged.
○: Equivalent to slightly lower than the reference (Comparative Example 1).
Δ: slightly lower than the reference (Comparative Example 1).
x: Significantly lower than the reference (Comparative Example 1).

(4) Evaluation 4 (paint adhesion/crosscut test)
Cellotape (registered trademark: CT-24 manufactured by Nichiban Co., Ltd.) was brought into close contact with the coating film for evaluation formed on the coated plate, pulled at an angle of 45 degrees, and the degree of peeling of the coating film was visually observed. Judgment criteria are as follows.
○: No peeling △: Slightly peeling ×: Peeling

Table 1 shows the evaluation results. The composite metal pigment according to the present invention, which satisfies all of the physical property requirements (1) to (6) obtained in each example, has good stability as a paint and generates little gas (that is, good It has excellent storage stability), exhibits high brightness, high flip-flop feeling and high concealability (that is, has good paint color tone), and is also excellent in adhesion as a coating film. confirmed.

The composite metal pigment of the present invention and the coating film or the like obtained by using it combine excellent design properties, gloss, suppression of pimples, stability in water-based paint, etc. at a high level beyond the limits of the prior art. Paints, inks, resin kneading agents, and various other applications where metallic pigments have been used. It can be suitably used in heat-resistant paints, anti-corrosion paints, ship bottom paints, offset printing inks, gravure printing inks, screen printing inks, etc., and can be used in the transportation machinery industry such as automobiles, the electrical and electronic industry such as home appliances, the paint industry, and the printing industry. It has high applicability in each field of industry such as.

Claims (7)

A metal pigment composition comprising composite particles having metal particles and one or more coating layers on the surface thereof,
(1) the shape of the composite particles is scaly,
(2) a volume-based _D50 of 3 μm or more and 30 μm or less when the particle size distribution of the composite particles is measured with a laser diffraction particle size distribution meter;
(3) the average thickness of the composite particles is 20 nm or more and 300 nm or less;
(4) at least one layer of the coating layer is a silicon compound-containing layer;
(5) In the composite particles, the ratio of the metal element content based on the metal particles to the silicon content based on the coating layer is 0.02 or more and 0.3 as a ratio of the silicon content to the metal element content. and
(6) The number ratio of the composite particles having a particle size of 0.1 μm or more and 1 μm or less is 10% or less of the total number of the composite particles in the metal pigment composition.
The above metal pigment composition. When the particle size distribution of the composite particles is measured with the laser diffraction particle size distribution meter, the number ratio of the composite particles having a particle size of 3 times or more the _D50 on a volume basis is the metal pigment composition. 2. The metal pigment composition according to claim 1, which accounts for 3% or less of the total number of said composite particles in the product. 3. A metal pigment composition according to claim 1 or 2, wherein the metal particles are aluminum or an aluminum alloy. 4. The metallic pigment composition according to any one of claims 1 to 3, further comprising a coating layer comprising at least one of metals, metal oxides, metal hydrates and resins. 5. The metal pigment composition according to any one of claims 1 to 4, wherein said at least silicon compound-containing layer is arranged as the outermost layer. A water-based metallic paint comprising the metallic pigment composition according to any one of claims 1 to 5. A metallic coating film comprising the metallic pigment composition according to any one of claims 1 to 5.