JPWO2018047360A1 - Resin-coated aluminum pigment - Google Patents

Abstract

The flat aluminum particle surface is coated with a coating resin containing an acrylic copolymer containing a structural unit derived from a radically polymerizable unsaturated carboxylic acid, and the surface of the coating resin with respect to the area of the coating resin, A resin-coated aluminum pigment, wherein a ratio of a total area of resin grains having an area equivalent circle diameter of 25 nm or more is 15 area% or less.

Description

  The present invention relates to a resin-coated aluminum pigment whose surface is coated with a resin.

Metallic paints are painted on automobile bodies and interior parts, household appliances such as refrigerators and washing machines, and portable electronic devices such as smartphones and mobile computers. Widely used for the purpose of granting. Metallic paints are usually blended with metallic powders such as aluminum, copper, nickel and titanium having a flat shape (also referred to as a scale shape), inorganic particles such as mica, and the like.
Conventionally, in these metallic pigments, metal atoms or inorganic compound molecules are exposed on the surface, so that it reacts with acid, alkali, chemicals, etc., and the smoothness of the pigment surface is impaired, and the glittering feeling of metallic coating is reduced. It has also been a cause of damage to the durability of the entire coated housing due to damage to the coating film and exposure of the substrate surface due to erosion.
In order to solve these problems, attempts have been made to form a polymer film on the surface of a metallic pigment to impart durability to acids, alkalis and chemicals.

For example, Patent Document 1 discloses a copolymer obtained by polymerizing a monomer having three or more radical polymerizable double bonds, a radical polymerizable unsaturated carboxylic acid and / or a phosphate ester having a radical polymerizable double bond. By coating the pigment surface, an aluminum pigment having excellent water resistance, chemical resistance, and fingerprint resistance is obtained.
Patent Document 2 is characterized in that when a ferrite layer is formed on a metal flake and the cut surface of the metal flake is observed with a transmission electron microscope, the primary particle diameter of the ferrite particle is less than 20 nm. It is said that a metal pigment having excellent design properties, heat resistance and chemical resistance can be obtained.
Patent Document 3 discloses a copolymer obtained by dispersing metal pigment particles in a solvent while adding an external vibrational action, and polymerizing monomers and / or oligomers having one or more double bonds in the molecule. By coating the pigment surface with a polymer, the surface roughness of the resin coating layer is below a certain level, and an aluminum pigment excellent in pigment dispersibility, chemical resistance, adhesion and gloss retention is obtained.

Japanese Patent Laid-Open No. 62-253668 JP-A-2015-178556 International Publication No. 2011/033655

  However, in the above technique, the polymer film coated on the surface of the metallic pigment is not uniform in thickness, so that not only the luminosity originally required as a metallic paint is impaired, but also an uncoated part in some cases (Pinhole) may exist, chemical resistance is poor, and the durability of the coating film is adversely affected.

  In view of the technical background as described above, the problem to be solved by the present invention is to provide a pigment that has excellent glitter and excellent chemical resistance against chemicals such as alkali.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention specified the ratio of the total area of the resin particles having an area equivalent circle diameter of 25 nm or more on the surface of the coating resin covering the surface of the aluminum particles. It was found that when the content was in the range, a pigment having good glitter and excellent chemical resistance was obtained, and the present invention was completed.

  That is, in the present invention, the flat aluminum particle surface is coated with a coating resin containing an acrylic copolymer containing a structural unit derived from a radically polymerizable unsaturated carboxylic acid, and the surface area of the coating resin is The present invention provides a resin-coated aluminum pigment in which the ratio of the total area of resin grains having an area equivalent circle diameter of 25 nm or more on the surface of the coating resin is 15 area% or less.

  The resin-coated aluminum pigment of the present invention is a resin-coated aluminum pigment in which the surface of flat aluminum particles is coated with a coating resin containing an acrylic copolymer containing a structural unit derived from a radically polymerizable unsaturated carboxylic acid. And the ratio of the total area of the resin grains having an area equivalent circle diameter of 25 nm or more to the surface of the coating resin to the area of the coating resin is 15 area% or less, so that the coating resin has a smooth and uniform thickness. Therefore, it has excellent glitter and chemical resistance against chemicals such as alkali.

It is a figure which shows the result of having image-analyzed the SEM image of the surface of the resin coating aluminum pigment of Example 1, detecting the resin particle of area circle equivalent diameter 25nm or more, and enclosing with the line. It is a figure which shows the result of having image-analyzed the SEM image of the surface of the resin coating aluminum pigment of the comparative example 1, detecting the resin particle more than an area circle equivalent diameter 25nm, and enclosing with the line. It is a graph which shows the evaluation result of chemical-resistance and the resin particle ratio (area%) of area circle equivalent diameter 25nm or more in the manufactured resin-coated aluminum pigment.

≪Resin-coated aluminum pigment≫
The resin-coated aluminum pigment of this embodiment (may be abbreviated as “coated pigment”) is a structural unit in which the surface of flat aluminum particles (A) is derived from radically polymerizable unsaturated carboxylic acid (B1). A resin-coated aluminum pigment coated with a coating resin containing an acrylic copolymer (B), wherein the area equivalent circle diameter of the surface of the coating resin with respect to the area of the coating resin is 25 nm or more. The ratio of the total area is 15 area% or less.

<Particle (A)>
The aluminum particles (A) according to the embodiment (may be abbreviated as “particles (A)”) are flat (scale-shaped) aluminum particles.
In one embodiment, the particles (A) may be inorganic particles or metal particles, or may be any particles containing inorganic or metal. As a metal, what remove | excluded the thing of the 1st period and the 2nd period among the things which belong to the periodic tables 1-15 group of an element is mentioned. Examples of inorganic and / or metallic materials include mica titanium, glass powder, aluminum powder, silver powder, copper powder, bronze powder, zinc powder, stainless steel powder, and nickel powder. Among these, metal dust is preferable, flat (scale-shaped) metal particles are more preferable, aluminum particles are more preferable, and flat (scale-shaped) aluminum particles are particularly preferable from the viewpoint of glitter.

  As the aluminum particles according to the embodiment, those produced by a conventionally known method can be widely used. When flat aluminum particles are used, substantially spherical aluminum particles may be ground and processed into flat aluminum particles, or may be processed into flat aluminum by a method such as vapor deposition. Examples of the processing method include a method using a ball mill and a method using vapor deposition. Examples include corn flakes or silver dollar shaped aluminum particles, vapor-deposited aluminum particles, and the like.

  Hereinafter, the shape of the particles (A) will be described. Usually, it is not assumed that only one particle (A) as a pigment is provided, so the values shown below are average values obtained for a plurality of provided particles (A). May be.

The average particle diameter of the particles (A) may be 100 μm or less, may be 0.1 μm to 100 μm, may be 1 μm to 80 μm, and may be 5 μm to 50 μm.
The average particle size of the particles (A) can be calculated as a volume-based median diameter d50 from a volume-based cumulative particle size distribution measured by a laser diffraction particle size distribution measuring device.
From the viewpoint of obtaining excellent glitter and dispersibility, the average particle diameter of the particles (A) is preferably 0.1 μm or more. Especially, it is preferable that the average particle diameter of particle | grains (A) is 5 micrometers or more from a viewpoint that the outstanding outstanding glitter and dispersibility are acquired. It is preferable that the average particle diameter of the particles (A) is 100 μm or less because precipitation of the particles hardly occurs and the glitter is good. In particular, it is preferable that the average particle diameter of the particles (A) is 50 μm or less because precipitation of the particles hardly occurs and the glitter is good.

When the particles (A) are flat, the average thickness of the particles (A) may be 1 μm or less, 0.001 μm to 1 μm, 0.01 to 0.8 μm, 0 .01 to 0.5 μm. The average thickness of the particles (A) is obtained by obtaining an average value of the thickness in a region selected at random for one particle (A), and then averaging the thicknesses of a plurality of particles (A). Value. Here, the term “multiple” means 10 or more.
The ratio R / t of the average particle diameter (R) and the average thickness (t) of the particles (A) is preferably 5 or more, 5 to 3000, 15 to 1500, 30 to 750. When the R / t of the particles (A) is within the above range, the particles have an appropriate flake shape, and thus excellent glitter can be easily obtained.

  The surface roughness Ra of the particles (A) is preferably 20 nm or less, and more preferably 15 nm or less. The surface roughness Rc of the particles (A) is preferably 80 nm or less, and more preferably 60 nm or less. When the surface roughness Ra and / or Rc is not more than the above upper limit value, the surface state of the particles (A) becomes smoother and excellent glitter is easily exhibited.

  Regarding the shape of the particles (A), it is preferable that the numerical ranges of two or more items are satisfied among the numerical ranges of the five items of average particle diameter, average thickness, R / t, Ra, and Rc.

<Acrylic copolymer (B)>
The acrylic copolymer (B) according to the embodiment includes a structural unit derived from the radical polymerizable unsaturated carboxylic acid (B1). The acrylic copolymer may contain a structural unit derived from the monomer (B2) having three or more radically polymerizable double bonds per molecule.
The acrylic copolymer (B) according to the embodiment includes a radically polymerizable unsaturated carboxylic acid monomer (B1) (may be abbreviated as “monomer (B1)”) and per molecule. It may be a radical polymer of a monomer (B2) having three or more radical polymerizable double bonds (may be abbreviated as “monomer (B2)”). The acrylic copolymer (B) according to the embodiment may include a structural unit derived from the monomer (B1) and a structural unit derived from the monomer (B2).

The monomer (B1) according to the embodiment is a radically polymerizable unsaturated carboxylic acid.
Examples of radically polymerizable unsaturated carboxylic acids include unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, unsaturated dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid, and half esters of these unsaturated dicarboxylic acids. Is mentioned. These monomers can be used alone or in combination of two or more.
The monomer (B1) may be a radical polymerizable phosphate ester. As the radical polymerizable phosphate ester, 2-methacryloyloxyethyl phosphate, di-2-methacryloyloxyethyl phosphate, tri-2-methacryloyloxyethyl phosphate, 2-acryloyloxyethyl phosphate, di-2-acryloyloxyethyl phosphate, Tri-2-acryloyloxyethyl phosphate, bis (2-hydroxyethyl methacrylate) phosphate, diphenyl-2-methacryloyloxyethyl phosphate, diphenyl-2-acryloyloxyethyl phosphate, dibutyl-2-methacryloyloxyethyl phosphate, dioctyl-2 -Acryloyloxyethyl phosphate, 2-methacryloyloxypropyl phosphate, etc. are mentioned.
These monomers can be used alone or in combination of two or more.

The monomer (B2) according to the embodiment may be a monomer having 3 or more radical polymerizable double bonds per molecule, and a monomer having 3 to 6 radical polymerizable double bonds per molecule. It may be a monomer, and may be a monomer containing 3 to 6 (meth) acryloyloxy groups per molecule.
Monomers containing 3 to 6 (meth) acryloyloxy groups per molecule include trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, glycerin triacrylate, ditrimethylolpropane tetramethacrylate, ditrimethylolpropanetetra. Acrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, etc., ethylene oxide (EO) and / or propylene oxide (PO) adducts of these monomers, or isocyanuric acid Examples include EO-modified triacrylate. These monomers can be used alone or in combination of two or more.

  In the coated pigment, when the acrylic copolymer (B) is a copolymer containing the monomer (B2), a constitutional unit derived from the monomer (B1) and a constitution derived from the monomer (B2) The molar ratio (B1: B2) to the unit is preferably 1: 1.5 to 1:10, more preferably 1: 1.5 to 1: 8, from the viewpoint of improving the coating state of the coating resin. : 1.5 to 1: 7 is more preferable.

<Polymerization initiator (C)>
The polymerization initiator (C) according to the embodiment is a radical polymerization initiator that generates at least radicals as active species, and examples thereof include azo polymerization initiators containing a nitrile group.
When an azo polymerization initiator containing a nitrile group is used as the polymerization initiator (C) according to the embodiment, the monomer (B1) and the monomer (B2) are subjected to a radical polymerization reaction, and the resulting acrylic is obtained. The structure represented by the following general formula (1) derived from the polymerization initiator (C) is included at the terminal of the system copolymer (B).

[In Formula (1), R ¹ represents a methyl group, R ² represents an alkyl group having 1 to 5 carbon atoms, a group represented by —C (═O) OR ^2a , or —C (═O) NHR ^2a The group represented by {The R ^2a represents an alkyl group having 1 to 8 carbon atoms. }, And R ¹ and R ² may be bonded to each other to form a cyclic structure. ]

The alkyl group having 1 to 5 carbon atoms of R ² may be linear or branched. Examples of the alkyl group having 2 to 5 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, and a neopentyl group.

The alkyl group having 1 to 8 carbon atoms of R ^2a may be linear or branched. Examples of the alkyl group having 1 to 8 carbon atoms include ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group, hexyl group, A heptyl group, an octyl group, etc. are mentioned.

In the formula (1), R ¹ preferably represents a methyl group, and R ² preferably represents an alkyl group having 2 to 5 carbon atoms.
In the formula (1), R ¹ preferably represents a methyl group, and R ² preferably represents a linear alkyl group having 2 to 5 carbon atoms.
In the formula (1), R ¹ preferably represents a methyl group, and R ² preferably represents an alkyl group having 2 to 3 carbon atoms.
In the formula (1), R ¹ preferably represents a methyl group, and R ² preferably represents a linear alkyl group having 2 to 3 carbon atoms.

  Examples of the azo polymerization initiator (C) containing a nitrile group include compounds represented by the following general formula (2).

[In formula (2), R ¹ and R ² represent the same meaning as in formula (1). ]

  Examples of the polymerization initiator (C) according to the embodiment include 2,2′-azobis (isobutyronitrile), 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2, 4-dimethylvaleronitrile), 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis (2-methylpropanenitrile) and the like, and 2,2′-azobis (2-methyl) Butyronitrile) is preferred.

  Examples of the other polymerization initiator (C) according to the embodiment include peroxides, such as potassium persulfate, sodium persulfate, ammonium persulfate, benzoyl peroxide, lauroyl peroxide, isobutyl peroxide, methyl ethyl ketone peroxide, diester Although-(t-butyl) cyclohexylidene diperoxide etc. are illustrated, it is not limited to these.

  90-140 degreeC may be sufficient as the temperature at the time of superposition | polymerization of the polymerization initiator (C) which concerns on embodiment, and 90-100 degreeC may be sufficient as it. The half-life time can be appropriately set depending on the polymerization temperature.

In one embodiment, the coated pigment is
A monomer (B1) of radically polymerizable unsaturated carboxylic acid or radically polymerizable phosphoric ester and a monomer (B2) containing 3 to 6 (meth) acryloyloxy groups per molecule are converted into a nitrile group. A radical polymerization reaction with a polymerization initiator (C) containing, to form an acrylic copolymer (B) on the inorganic or metal particles (A),
The inorganic or metal particles (A) are coated with a coating resin containing the copolymer (B),
It may include a structure represented by the following general formula (1) derived from the polymerization initiator (C) at the terminal of the acrylic copolymer (B).

[In Formula (1), R ¹ represents a methyl group, R ² represents an alkyl group having 1 to 5 carbon atoms, a group represented by —C (═O) OR ^2a , or —C (═O) NHR ^2a The group represented by {The R ^2a represents an alkyl group having 1 to 8 carbon atoms. }, And R ¹ and R ² may be bonded to each other to form a cyclic structure. ]

<Particle (A) and coating resin>
Hereinafter, the particles (A) and the coating resin in the coated pigment of the embodiment will be described. Here, since it is not normally assumed that the coated pigment is provided by only one pigment particle, the values shown below may be obtained as an average value for the provided coated pigment.

  In the coated pigment of the embodiment, the particles (A) are coated with a coating resin containing an acrylic copolymer (B).

  The coating resin preferably contains 50% by mass or more of the acrylic copolymer (B), more preferably contains 80% by mass or more, more preferably contains 95% by mass or more, and contains 99% by mass or more. It is particularly preferred. Alternatively, the coating resin may be composed only of the acrylic copolymer (B).

  In the present specification, the particle (A) being “coated with a coating resin” means a state in which the coating resin is laminated on a part or all of the surface of the particle (A). The coating resin is preferably bonded directly to the surface of the particle (A). Examples of types of bonds include chemical bonds such as covalent bonds, coordination bonds, and ionic bonds. When the coating resin is bonded to the surface of the particle (A), the coating resin can be hardly peeled off from the particle (A).

In the coated pigment of the embodiment, the mass ratio of the particles (A) to the coating resin (particles (A): coating resin) is preferably 50:50 to 99.9: 0.1, and 70:30 to 99.7. : 0.3 is particularly preferable. When the mass ratio of the particles (A) and the coating resin is within the above range, the balance between the glitter of the particles (A) and the chemical resistance of the coating resin is preferable. Further, the coating of the coating resin on the particles (A) is thin, which is preferable from the viewpoint of glitter.
In applications in which chemical resistance is particularly important, such as pre-coated metal applications, it is preferable that the resin to be coated is thick within a range where the balance between glitter and chemical resistance can be taken, and 70:30 to 90:10 is particularly preferable.
Also, in applications where glitter is particularly important, in order to make the most of the light reflectivity of the aluminum pigment itself, it is preferable that the resin to be coated is thinner within a range where the balance between glitter and chemical resistance can be achieved. 80:20 to 99: 1, particularly 80:20 to 95: 5 is preferred.

In the coated pigment of the embodiment, the mass [g] of the monomer (B1) per the total surface area [m ² ] of the particle (A) (the mass [g] of the monomer (B1) / the total of the particles (A) The surface area [m ² ] is preferably 5 × 10 ^{−4 to} 35 × 10 ⁻⁴ [g / m ² ], more preferably 7 × 10 ^{−4 to} 25 × 10 ⁻⁴ [g / m ² ]. × 10 ^{−4 to} 20 × 10 ⁻⁴ [g / m ² ] is more preferable.
When the mass of the monomer (B1) per total surface area of the particles (A) is within the above range, the balance between the glitter of the particles (A) and the chemical resistance of the coating resin is preferable. Moreover, since the monomer (B1) can be a starting point for the polymerization of the acrylic copolymer (B), the mass of the monomer (B1) per particle (A) total surface area is 6 × 10 ^{−. By being 4} or more, it is considered that radical polymerization on the surface of the particle (A) proceeds in a more uniform state between the regions. As a result, a coating resin having a smooth and uniform thickness can be obtained.

  The total surface area of the particles (A) can be calculated from the specific surface area of the particles (A) measured using a specific surface area meter and the mass of the particles (A).

The coating resin may have resin particles. The resin particle according to the embodiment can be formed by radical polymerization of the copolymer (B) on the particle (A), and can be a hemispherical copolymer.
As an indicator of the degree of “smooth” and “uniform thickness” of the coating resin, in the coating pigment of the embodiment, the surface equivalent circle diameter of the surface of the coating resin with respect to the area of the coating resin is 25 nm or more. The ratio of the total area is 15 area% or less, more preferably 13 area% or less, further preferably 5 area% or less, and particularly preferably 2 area% or less. The coating pigment whose ratio of the total area of resin grains having an area equivalent circle diameter of 25 nm or more is not more than the above upper limit value is excellent in glitter and chemical resistance because the coating resin has a smooth and uniform thickness. Yes.
The ratio of the total area (projected area) of resin grains having an area equivalent circle diameter of 25 nm or more to the surface of the coated resin with respect to the area (projected area) of the coated resin is, for example, with respect to the SEM image file of the coated pigment The Heywood diameter (area circle equivalent diameter) is calculated for each resin particle observed in the measurement area, and the ratio of resin particles having an area equivalent circle diameter of 25 nm or more with respect to the adhered resin observed on the surface of the resin-coated aluminum pigment. (Area%) can be calculated by the following formula.
The total area of the area circle equivalent diameter 25nm or more resins grain proportion (area%) = area circle equivalent diameter 25nm or more resins grain in the measurement area ([mu] m ²⁾ / measured area size ([mu] m ²⁾ × 100
In addition, the image used for the measurement uses only the portion where the coating resin was imaged as the measurement area, and the total area of the resin grains having an area equivalent circle diameter of 25 nm or more is calculated from each area equivalent circle diameter. . The value may be calculated as an average value of observation results for the particle surfaces of the plurality of coated particles.

The coated pigment of the embodiment can be produced by a method for producing a coated pigment, which will be described later, as an example.
The coated pigment of the embodiment is
(I) reacting the particles (A) with the monomer (B1),
(Ii) The monomer (B1) or a structure derived therefrom and the monomer (B2) are subjected to a radical polymerization reaction with the polymerization initiator (C), whereby inorganic or metal particles (A) are formed. Forming an acrylic copolymer (B);
The inorganic or metal particles (A) are coated with a coating resin containing an acrylic copolymer (B),
The terminal of the acrylic copolymer (B) may include a structure represented by the following general formula (1) derived from the polymerization initiator (C).

[In the formula (1), R ¹ represents a methyl group, R ² represents an alkyl group having 1 to 5 carbon atoms, a group represented by —C (═O) —O—R ^2a , or —C (═O ) Group represented by —NH—R ^2a {wherein R ^2a represents an alkyl group having 1 to 8 carbon atoms. }, And R ¹ and R ² may be bonded to each other to form a cyclic structure. ]
What was illustrated above about a metal particle (A), an acryl-type copolymer (B), a monomer (B1), a monomer (B2), a polymerization initiator (C), and Formula (1) is mentioned. It is done.

The radical polymerization reaction is preferably performed under a condition where the half-life time of the initiator is 3 to 45 minutes, preferably 4 to 40 minutes. More preferably, it was performed under the condition of ~ 35 minutes, more preferably it was performed under the condition of 5-20 minutes, and it was performed under the condition of 5-10 minutes. It is particularly preferred.
The radical polymerization reaction may be performed under conditions where the initiator half-life time is 5 to 15 minutes, or may be performed under conditions of 15 to 25 minutes. It may be performed under conditions of 25 to 35 minutes.

<Paint / Ink>
The coated pigment of the embodiment can be used as a paint or ink. As one embodiment, a paint or ink containing the coated pigment of the embodiment can be provided. Examples of the paint include powder paint, furniture paint, electrical appliance paint, automobile paint, plastic paint, and the like. Examples of the ink include printing ink, packaging material printing ink, and the like.

The paint or ink may contain the coated pigment of the embodiment, a dispersion medium, and a resin for paint or ink. As the dispersion medium, any dispersion medium used for dispersing a metal pigment can be used, and a conventionally known dispersion medium may be used. Examples of the dispersion medium include alcohol solvents such as ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, and isobutyl alcohol; ester solvents such as ethyl acetate, propyl acetate, and butyl acetate, methyl ethyl ketone, methyl butyl ketone, and cyclohexanone. Ketone solvents such as methyl ether solvent, ether ester solvents such as butyl cellosolv acetate, amide solvents such as dimethylformamide and dimethylacetamide, aromatic hydrocarbon solvents such as toluene and xylene, hexane, heptane, white spirits, etc. Examples thereof include aliphatic hydrocarbon solvents, and mixed solvents of aromatic hydrocarbons and aliphatic hydrocarbons such as mineral spirits.
As the paint or ink resin, any resin blended into the paint or ink can be used, and a conventionally known resin may be used. Examples of the resin include acrylic resin, polyester resin, alkyd resin, urethane resin, epoxy resin, polyvinyl acetate copolymer resin, polyamide resin, and melamine resin.
In addition to the coating pigment of the embodiment, the paint or ink pigment may further contain any coloring pigment that does not correspond to the coating pigment of the embodiment and is blended into the coating or ink. The coloring pigments may be used. Color pigments include phthalocyanine pigments, halogenated phthalocyanine pigments, quinacridone pigments, diketopyrrolopyrrole pigments, isoindolinone pigments, azo pigments, azomethine metal complex pigments, indanthrone pigments, and perylenes. Pigment, Perinone pigment, Anthraquinone pigment, Dioxazine pigment, Benzimidazolone pigment, Condensed azo pigment, Triphenylmethane pigment, Quinophthalone pigment, Anthrapyrimidine pigment, Titanium oxide, Iron oxide, Carbon black, Vanadium Bismuth acid is mentioned.

  For example, the paint or ink preferably contains 0.5 to 50% by mass of the coated pigment, more preferably 5 to 40% by mass, and even more preferably 10 to 30% by mass.

  In addition to the coated pigment of the embodiment, the paint or ink may be used as necessary, such as an anti-aging agent, an antiseptic, a softening agent, an ultraviolet absorber, an antioxidant, a light stabilizer, a heat stabilizer, and an antistatic agent. Various additives may be contained.

In the coating resin of the coating pigment of the embodiment, the ratio of the total area of the resin grains having an area equivalent circle diameter of 25 nm or more on the surface of the coating resin to the area of the coating resin is 15 area% or less. When the resin particle diameter is small, the unevenness on the surface of the resin-coated pigment becomes small, so that irregular reflection of light hardly occurs, and a reduction in glitter can be prevented.
The coated pigment of the embodiment is preferably coated with a coating resin containing an acrylic copolymer (B) that has undergone radical polymerization reaction with a polymerization initiator (C). When the monomer (B1) and the monomer (B2) are subjected to a radical polymerization reaction using the polymerization initiator (C) according to the embodiment, the resulting acrylic copolymer (B) is obtained. The coating resin to be contained has a smooth and uniform thickness, and the coating pigment has a good glitter and excellent chemical resistance. This is probably because the half-life time at the polymerization temperature of the polymerization initiator (C) is relatively short, so that the amount of radicals supplied per hour increases, and the size of the formed resin particles decreases. Thus, the number of formed resin particles is increased, and the progress of radical polymerization reaction between the regions becomes more uniform. As a result, it is considered that the coating resin having a smooth and uniform thickness is formed.

By using the polymerization initiator (C), the molecular weight of the acrylic copolymer (B) obtained as compared with the prior art becomes small. As a result, the size of the resin particles that grow on the resin surface is smaller than that of the prior art. As a result, the void area generated between the resin particles that are the formed hemispherical copolymer can be made small enough to be ignored. This means that the exposed area of the inorganic or metal particles is almost eliminated, and it is difficult to be corroded by acid or alkali, and it is possible to ensure excellent chemical resistance.
Moreover, since the unevenness | corrugation on the surface of a resin coating pigment will become small if the diameter of a resin particle is small, irregular reflection of light does not occur easily and it can prevent the fall of a glittering feeling.
If the coating resin layer is thickened, the chemical resistance can be improved. However, if the coating resin layer is thick, the glitter is impaired. On the other hand, since the coating resin of the embodiment has a smooth and uniform thickness, the glitter and chemical resistance are very good.
If the surface of the resin is not smooth, when a force is applied to the convex portion, it becomes a cause of easy peeling. On the other hand, since the coating resin of the embodiment has a smooth and uniform thickness, the coating film durability can be improved in addition to the glitter and chemical resistance.
The smooth and uniform thickness of the coating resin means that the thickness of the coating resin can be reduced as compared with a coating pigment having the same chemical resistance, and the original particles (A) have better brightness. To be demonstrated.

≪Method for producing coated pigment≫
The method for producing the coated pigment of the embodiment is as follows:
It has the process of coat | covering the surface of particle | grains (A) with the coating resin containing an acryl-type copolymer (B).

The method for producing the coated pigment of the embodiment is as follows:
(I) a step of reacting the particles (A) with the monomer (B1),
(Ii) The monomer (B1) or a structure derived therefrom and the monomer (B2) are subjected to a radical polymerization reaction with a polymerization initiator (C) containing a nitrile group, whereby particles (A) Forming an acrylic copolymer (B) on
The inorganic or metal particles (A) are coated with a coating resin containing an acrylic copolymer (B),
The radical polymerization reaction is performed under a condition where the initiator has a half-life time of 3 to 45 minutes,
A structure represented by the following general formula (1) derived from the polymerization initiator (C) may be included at the terminal of the acrylic copolymer (B).

[In the formula (1), R ¹ represents a methyl group, R ² represents an alkyl group having 1 to 5 carbon atoms, a group represented by —C (═O) —O—R ^2a , or —C (═O ) Group represented by —NH—R ^2a {wherein R ^2a represents an alkyl group having 1 to 8 carbon atoms. }, And R ¹ and R ² may be bonded to each other to form a cyclic structure. ]

  In the method for producing the coated pigment of the embodiment, the metal particles (A), the acrylic copolymer (B), the monomer (B1), the monomer (B2), the polymerization initiator (C), and the formula (1) ), Those exemplified in the above << resin-coated inorganic or metal pigment >> are mentioned, and detailed description thereof is omitted.

  The step (i) may be a step of reacting the particle (A) with the monomer (B1) to form a bond between the particle (A). Examples of types of bonds include chemical bonds such as covalent bonds, coordination bonds, and ionic bonds.

  The step (i) may be a step of forming a bond between the atom on the outermost surface of the particle (A) and the monomer (B1). Examples of types of bonds include chemical bonds such as covalent bonds, coordination bonds, and ionic bonds.

According to the said process (i), it will be in the state which the structure derived from the monomer (B1) or the monomer (B1) produced as a result of reaction couple | bonded with the surface of particle | grains (A). The monomer (B1) bonded to the surface of the particle (A) or a structure derived therefrom can be a starting point for subsequent radical polymerization.
According to the said process (ii), an acrylic copolymer (B) can be formed in the surface of particle | grains (A).

  The acrylic copolymer (B) of the coated pigment produced through the steps (i) and (ii) is a structural unit derived from the monomer (B1) from the particle (A) side. The structural unit derived from the monomer (B2) may be included in this order.

  In step (i) and step (ii), the reaction can proceed in the reaction solution. The reaction liquid in the step (i) can contain particles (A), a monomer (B1), a solvent and / or a dispersion medium, and other components as necessary. The reaction liquid in the step (ii) includes a reaction product of the particles (A) and the monomer (B1), a polymerization initiator (C), a monomer (B2), a solvent and / or a dispersion medium, Other components can be included as necessary.

  An organic solvent is mentioned as a solvent and / or a dispersion medium. Examples of organic solvents include ester solvents such as ethyl acetate, propyl acetate, and butyl acetate; ketone solvents such as methyl ethyl ketone, methyl butyl ketone, and cyclohexanone; ether ester solvents such as methyl cellosolve acetate and butyl cellosolve acetate; toluene, xylene, and the like. Examples include aromatic hydrocarbon solvents, amide solvents such as dimethylformamide and dimethylacetamide, and petroleum solvents such as mineral spirits. Examples of other components include a chain transfer agent for radical polymerization reaction.

As an example, the temperature of the reaction liquid in the step (i) is about 80 to 120 ° C.
The temperature of the reaction solution in step (ii) is the reaction temperature of the radical polymerization reaction, and as an example, it may be 80 to 140 ° C, 85 to 105 ° C, or 90 to 100 ° C. Also good.

The radical polymerization reaction is preferably performed under a condition where the half-life time of the polymerization initiator (C) is 2 to 220 minutes, and is performed under a condition of 3 to 45 minutes. It is preferable that the reaction is carried out under the condition of 4 to 40 minutes, more preferably the reaction is performed under the condition of 5 to 35 minutes, and the reaction is performed under the condition of 5 to 20 minutes. It is more preferable that the reaction is performed under conditions of 5 to 10 minutes.
The radical polymerization reaction may be performed under conditions where the initiator half-life time is 5 to 15 minutes, or may be performed under conditions of 15 to 25 minutes. It may be performed under conditions of 25 to 35 minutes.

  According to the method for producing a coated pigment of the embodiment, the coated pigment of the embodiment is produced by performing the step (i) and the step (ii).

  When the monomer (B1) and the monomer (B2) are subjected to a radical polymerization reaction using the polymerization initiator (C) according to the embodiment, the resulting acrylic copolymer (B) is obtained. The coating resin to be contained has a smooth and uniform thickness, and the coating pigment has a good glitter and excellent chemical resistance.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, “part” and “%” are based on mass.

[Production of resin-coated aluminum pigment]
The resin-coated aluminum pigment according to the present invention was produced as follows.

<Example 1>
In a 3 L four-necked flask, 326 g of raw material A: aluminum paste “MAXAL 64064” (Benda-Lutz Werke, average particle size 15 μm, flat shape, metal content 67 mass%) and mineral spirit (JX Nippon Oil & Gas Company) (Made by Energy Co., Ltd.) 854 g was added, and the temperature was raised to 100 ° C. in an inert gas atmosphere. Next, an acrylic acid solution (raw material B1: 2.0 g of acrylic acid dissolved in mineral spirit and prepared into a 10.0% by mass solution) was added dropwise over 15 minutes and stirred at 100 ° C. for 1 hour. Through this step, a chemical bond was formed between the surface of the aluminum particles of the raw material A and the acrylic acid of the raw material B1. Bond formation was confirmed by FT-IR.
Next, monomer solution (raw material B2: trimethylolpropane trimethacrylate 33 g dissolved in mineral spirit and prepared to 50.0 mass% solution) and initiator solution (raw material C: 2,2′-azobis (2- Methyl butyronitrile) 0.5 g dissolved in mineral spirits and prepared in a 0.25 mass% solution) was added dropwise simultaneously over 90 minutes, and then polymerized at 100 ° C. for 5 hours. After completion of the polymerization, the reaction solution was cooled to room temperature, and the reaction solution was filtered and washed with mineral spirits to obtain a resin-coated aluminum pigment as a paste-like glittering material. The mass ratio of the metal component and the resin coating layer in the pigment was 86:14.

<Example 2>
Example 1 and Example 1 except that the raw material A was changed to the aluminum paste “MAXAL 64047” (Benda-Lutz Werke, average particle size 21.5 μm, flat shape, metal content 67 mass%) in Example 1 above. A resin-coated aluminum pigment was obtained in the same manner.

<Example 3>
Example 1 and Example 1 except that the raw material A was changed to the aluminum paste “MAXAL 64054” (Benda-Lutz Werke, average particle size 17.0 μm, flat shape, metal content 67 mass%) in Example 1 above. A resin-coated aluminum pigment was obtained in the same manner.

<Example 4>
326 g of raw material A: aluminum paste “MAXAL 64064” (Benda-Lutz Werke, average particle size 15 μm, flat shape, metal content 67% by mass) and mineral spirit 854 g are added to a 3 L four-necked flask and inert. The temperature was raised to 100 ° C. in a gas atmosphere. Next, an acrylic acid solution (raw material B1: 2.0 g of acrylic acid dissolved in mineral spirit and prepared into a 10.0% by mass solution) was added dropwise over 15 minutes and stirred at 100 ° C. for 1 hour. Through this step, a chemical bond was formed between the surface of the aluminum particles of the raw material A and the acrylic acid of the raw material B1.
Next, a monomer solution (raw material B2: 33 g of trimethylolpropane trimethacrylate dissolved in mineral spirit and prepared to a 50.0% by mass solution) and an initiator solution (raw material C: di- (t-butyl) cyclohexylene Dendiperoxide 0.7 g was dissolved in mineral spirits and prepared in a 0.35 mass% solution) was added dropwise simultaneously over 90 minutes, and then polymerized at 133 ° C. for 2 hours. After completion of the polymerization, the reaction solution was cooled to room temperature, and the reaction solution was filtered and washed with mineral spirits to obtain a resin-coated aluminum pigment as a paste-like glittering material. The mass ratio of the metal component and the resin coating layer in the pigment was 86:14.

<Comparative Example 1>
326 g of raw material A: aluminum paste “MAXAL 64064” (Benda-Lutz Werke, average particle size 15 μm, flat shape, metal content 67 mass%) and mineral spirit 854 g were added to a 3 L four-necked flask. The temperature was raised to 100 ° C. in an active gas atmosphere. Next, the raw material B1: 2.0g of acrylic acid was added, and it stirred at 100 degreeC for 1 hour. By this step, a chemical bond was formed between the surface of the aluminum particles of the raw material A and the acrylic acid of the raw material B1.
Next, the whole amount of the monomer solution (raw material B2: 33 g of trimethylolpropane trimethacrylate dissolved in mineral spirit and prepared in a 50.0 mass% solution) was added, and then the initiator solution (raw material C: 2, 2 ′ -4.0 g of azobis (2-methylbutyronitrile) dissolved in mineral spirit and prepared in a 2.0 mass% solution) was added dropwise over 30 minutes, and polymerized at 100 ° C for 5 hours. After completion of the polymerization, the reaction solution was cooled to room temperature, and the reaction solution was filtered and washed with mineral spirits to obtain a resin-coated aluminum pigment as a paste-like glittering material.

<Comparative example 2>
Resin-coated aluminum particles were obtained in the same manner as in Comparative Example 1 except that the amount of mineral spirit used was changed from 854 g to 3106 g in Comparative Example 1 above.

<Comparative Example 3>
326 g of raw material A: aluminum paste “MAXAL 64064” (Benda-Lutz Werke, average particle size 15 μm, flat shape, metal content 67 mass%) and mineral spirit 1134 g are added to a 3 L four-necked flask and inert. The temperature was raised to 80 ° C. in a gas atmosphere. Next, raw material B1: 1.1 g of acrylic acid was added and stirred at 80 ° C. for 30 minutes. Through this step, a chemical bond was formed between the surface of the aluminum particles of the raw material A and the acrylic acid of the raw material B1.
Next, the whole amount of raw material B2: 21 g of trimethylolpropane trimethacrylate and 2.1 g of 2,2′-azobisisobutyronitrile was charged and polymerized at 80 ° C. for 5 hours. After completion of the polymerization, the reaction solution was cooled to room temperature, and the reaction solution was filtered and washed with mineral spirits to obtain a resin-coated aluminum pigment as a paste-like glittering material.

<Comparative example 4>
326 g of raw material A: aluminum paste “MAXAL 64064” (Benda-Lutz Werke, average particle size 15 μm, flat shape, metal content 67% by mass) and mineral spirit 854 g are added to a 3 L four-necked flask and inert. The temperature was raised to 100 ° C. in a gas atmosphere. Next, an acrylic acid solution (raw material B1: 6.5 g of acrylic acid dissolved in mineral spirit and prepared to be a 10.0% by mass solution) was added dropwise over 15 minutes and stirred at 100 ° C. for 1 hour. Through this step, a chemical bond was formed between the surface of the aluminum particles of the raw material A and the acrylic acid of the raw material B1.
Next, monomer solution (raw material B2: trimethylolpropane trimethacrylate 33 g dissolved in mineral spirit and prepared to 50.0 mass% solution) and initiator solution (raw material C: 2,2′-azobis (2- Methylbutyronitrile) (4.0 g) dissolved in mineral spirits and prepared in a 0.25 mass% solution) was added dropwise simultaneously over 90 minutes, and then polymerized at 100 ° C. for 5 hours. After completion of the polymerization, the reaction solution was cooled to room temperature, and the reaction solution was filtered and washed with mineral spirits to obtain a resin-coated aluminum pigment as a paste-like glittering material.
In Comparative Example 4, gel resin particles were generated in the reaction solution after the addition of the trimethylolpropane trimethacrylate and the initiator solution and could not be formed into a coating material, and thus the subsequent evaluation was not performed.

  The obtained resin-coated aluminum pigment was evaluated by the following method.

[SEM measurement]
The resin-coated aluminum pigment is ultrasonically cleaned with excess n-hexane for 10 minutes, the solution is filtered, then ultrasonically cleaned and filtered again with n-hexane, and then naturally dried to measure the resin-coated aluminum pigment. A sample was obtained.
Subsequently, platinum was vapor-deposited on the measurement sample, and the pigment surface was observed and evaluated with a scanning electron microscope (JEM7800F manufactured by SEM JEOL). The measurement magnification was 50000 times.

(Image analysis particle size distribution measurement)
With respect to the SEM image file obtained by the above [SEM measurement], resin particles observed on the surface of the aluminum pigment with image analysis type particle size distribution measurement software (“Mac-View” Ver.4, manufactured by Mountec Co., Ltd.) The distribution of was measured.
The diameter of the resin particles was measured for each resin particle observed in the measurement area, and the Heywood diameter (area circle equivalent diameter) was calculated. From the calculation results, the ratio (area%) of resin particles having an area equivalent circle diameter of 25 nm or more was calculated for the adhered resin observed on the surface of the resin-coated aluminum pigment.
The total area of the area circle equivalent diameter 25nm or more resins grain proportion (area%) = area circle equivalent diameter 25nm or more resins grain in the measurement area ([mu] m ²⁾ / measured area size ([mu] m ²⁾ × 100
In addition, since the image used for the measurement used only the part where the coating resin was imaged as the measurement area, the measurement area area corresponds to the area of the coating resin. The total area of resin grains having an area circle equivalent diameter of 25 nm or more was calculated from each area circle equivalent diameter. The value was calculated as the average value of the observation results for the particle surfaces of a plurality of resin-coated aluminum pigments.
Table 1 and FIG. 1 and FIG. 2 show the results of the resin particle ratio (area%) having an area equivalent circle diameter of 25 nm or more.
FIG. 1 shows an example of the image analysis type particle size distribution measurement result of the SEM image file of the resin-coated aluminum pigment of Example 1. FIG. 2 shows an example of the image analysis type particle size distribution measurement result of the SEM image file of the resin-coated aluminum pigment of Comparative Example 1. In FIG. 1 and FIG. 2, a region surrounded by a line (partially shaded) indicates resin grains having an area circle equivalent diameter of 25 nm or more.

[Aluminum specific surface area measurement: BET method]
The resin-coated aluminum pigment is ultrasonically cleaned with excess n-hexane for 10 minutes, the solution is filtered, then ultrasonically cleaned and filtered again with n-hexane, and then naturally dried to measure the resin-coated aluminum pigment. A sample was obtained.
About the obtained sample for a measurement, it measured with the specific surface area meter (The product made by Mountec, Macsorb Model-1208). The specific surface area of aluminum (m ² / g) was determined as the surface area per 1 g of resin-coated aluminum pigment measured from the amount of nitrogen gas adsorbed by the BET method, and the total surface area (m ² ) of the aluminum pigment used was measured. Calculated as aluminum specific surface area (m ² / g) × aluminum pigment paste mass (g) × solid content ratio (%), the mass (g) of acrylic acid per aluminum unit area (m ² ) is the acrylic used It calculated as acid amount (g) / aluminum total surface area (m ² ).

[Evaluation of chemical resistance]
Resin-coated aluminum pigment (nonvolatile content) 4.4 parts by mass, varnish {Beckolite (registered trademark) M-6603-60, manufactured by DIC Corporation} 12.3 parts by mass, Super Becamine (registered trademark) L-105 -60 (manufactured by DIC Corporation) 1.8 parts by mass, 1.8 parts by mass of Super Becamine (registered trademark) J-820-60 (manufactured by DIC Corporation), and a mixed solvent (Solvesso (registered trademark) 100 (exxon) (Mobil Co., Ltd.): n-butanol = 1: 2) 9.6 parts by mass were mixed and coated on a plastic plate. The obtained coated plate was dried at room temperature for 30 minutes, and then the coated plate was heated at 140 ° C. for 15 minutes to cure the coating film.
Three drops of a 10% (w / v) aqueous sodium hydroxide solution were dropped on the coated plate obtained above with a dropper and stored at room temperature for 15 hours. Thereafter, the coated plate was washed with water and dried, and the chemical resistance was determined by visual evaluation of the color difference of the coating film before and after dropping the aqueous sodium hydroxide solution. Evaluation of chemical resistance is “excellent”: “10” when the color difference cannot be confirmed before and after dropping the sodium hydroxide aqueous solution, “poor”: “1” when the aluminum in the dropping portion of the sodium hydroxide aqueous solution is completely dissolved. As a result, relative evaluation was performed in 10 stages. The results are shown in Table 1.

  FIG. 3 shows a plot of the evaluation results of the chemical resistance evaluated above and the ratio of resin grains (area%) having an area equivalent circle diameter of 25 nm or more. The smaller the proportion of resin particles having an area equivalent circle diameter of 25 nm or more, the better the chemical resistance.

  Each configuration in each embodiment, a combination thereof, and the like are examples, and the addition, omission, replacement, and other changes of the configuration can be made without departing from the spirit of the present invention. Further, the present invention is not limited by each embodiment, and is limited only by the scope of the claims.

  According to the present invention, it is possible to provide a pigment having excellent glitter and excellent chemical resistance against chemicals such as alkali.

Claims (3)

The flat aluminum particle surface is coated with a coating resin containing an acrylic copolymer containing a structural unit derived from a radically polymerizable unsaturated carboxylic acid,
The resin-coated aluminum pigment, wherein the ratio of the total area of resin grains having an area equivalent circle diameter of 25 nm or more to the surface of the coating resin is 15 area% or less with respect to the area of the coating resin.   The resin-coated aluminum pigment according to claim 1, wherein the acrylic copolymer contains a structural unit derived from a monomer having three or more radically polymerizable double bonds per molecule.   The molar ratio of the structural unit derived from the radically polymerizable unsaturated carboxylic acid and the structural unit derived from the monomer having 3 or more radically polymerizable double bonds per molecule is 1: 1.5 to 1: The resin-coated aluminum pigment according to claim 2, wherein the resin-coated aluminum pigment is 10.