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JP-7856504-B2 - Method for producing a metal pigment composition

JP7856504B2JP 7856504 B2JP7856504 B2JP 7856504B2JP-7856504-B2

Inventors

  • 福原 信太郎

Assignees

  • 旭化成株式会社

Dates

Publication Date
20260511
Application Date
20220622

Claims (7)

  1. (I) A step of dispersing metal particles in a solvent containing at least a hydrophobic solvent to obtain a metal particle dispersion, (II) A step of adding an aqueous solution of salt to the metal particle dispersion to obtain a phase separated into a hydrophilic phase and a hydrophobic solvent phase, (III) A step of adding a raw material and catalyst for the polysiloxane compound, and while the phase-separated phase is in a phase-separated state, coating the surface of the metal particles with the polysiloxane compound, A method for producing a metal pigment composition characterized by containing the following:
  2. A method for producing a metal pigment composition according to claim 1, wherein the total amount of solvent in step (I) is 10 parts by mass or more and 1000 parts by mass or less per 100 parts by mass of metal particles.
  3. The method for producing a metal pigment composition according to claim 2, wherein the solvent in step (I) comprises a hydrophobic solvent and a hydrophilic solvent, and the mass ratio of the hydrophobic solvent to the hydrophilic solvent (mass of hydrophobic solvent / mass of hydrophilic solvent) is 1/1 to 1/24.
  4. A method for producing a metal pigment composition according to any one of claims 1 to 3, wherein the amount of salt added in step (II) is 0.1 to 40 parts by mass per 100 parts by mass of metal particles.
  5. A method for producing a metal pigment composition according to any one of claims 1 to 3, wherein the pKa of the acid constituting the salt added in step (II) is 3.0 to 5.5.
  6. A method for producing a metal pigment composition according to any one of claims 1 to 3, wherein in the coating process of step (III) above, a silicon-containing compound which is at least one of the following general formula (1), tetrahalosilane, silane coupling agents of general formulas (3) to (5), and partial condensates thereof is used as a raw material for the polysiloxane compound. Si(OR 1 ) 4 (1) (In the formula, R1 is a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and may be entirely identical, partially identical, or entirely different.) Six 1 4 (2) (In the formula, X1 is one of the following: a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and these may all be the same, some may be the same, or all may be different.) R 2 m Si(OR 3 ) 4-m (3) (In the formula, R2 is a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, which may optionally include a halogen group, and R3 is a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms. R2 and R3 may be the same or different, and if there are two or more R2 or R3 , they may all be the same, partially the same, or all different. 1 ≤ m ≤ 3.) R 4 p R 5 q Si(OR 6 ) 4-pq (4) (In the formula, R4 is a group containing a reactive group that can chemically bond with other functional groups, R5 is a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, which may optionally contain a halogen group, and R6 is a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms. If there are two or more R4 , R5 , or R6 , they may all be the same, partially the same, or all different. 1 ≤ p ≤ 3, 0 ≤ q ≤ 2, and 1 ≤ p + q ≤ 3.) R 7 r SiX 2 4-r (5) (In the formula, R7 is a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, which may optionally include a halogen group. R7 may be the same or different. If there are two or more R7s , they may all be the same, partially the same, or all different. 1 ≤ r ≤ 3. X2 is one of a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. If there are two or more X2s , they may all be the same, partially the same, or all different.)
  7. A method for producing a metal pigment composition according to any one of claims 1 to 3, wherein the metal particles are aluminum.

Description

This invention relates to a method for producing a metal pigment composition suitable for paint compositions or ink compositions, particularly water-based paints or water-based inks. Traditionally, metallic pigment compositions have been used in metallic paints, printing inks, and plastic compounding applications to achieve a metallic aesthetic effect. In recent years, the paint industry has seen a growing need to shift to water-based paints, which use less organic solvents, as a measure to conserve resources and reduce pollution. However, the manufacturing methods for metallic pigment compositions usable in water-based paints often involve the use of hydrophilic organic solvents, and further reductions in the amount of organic solvents used during manufacturing are desirable. Patent Document 1 discloses an aluminum pigment whose surface is coated with a polysiloxane compound produced under conditions using a basic catalyst, including monoethanolamine. In the method for producing the aluminum pigment described in that document, due to concerns about increasing the viscosity of the slurry, it is preferable to use 500 parts by mass or more of a hydrophilic organic solvent per 100 parts by mass of aluminum particles. Furthermore, Patent Document 2 discloses a metal pigment composition whose surface is coated with a polysiloxane compound produced under conditions using a basic catalyst such as ammonia or an acidic catalyst. In the method for producing the metal pigment composition described in the document, the concentration of metal particles in the slurry is preferably 5 to 20% by mass. That is, it is preferable to use 400 parts by mass or more of organic solvent per 100 parts by mass of metal particles. Patent No. 3948934Japanese Patent Publication No. 2019-151678 The present invention will be described in detail below, with particular emphasis on its preferred embodiments. The present invention relates to the following manufacturing method: (I) A step of dispersing metal particles in a solvent containing at least a hydrophobic solvent to obtain a metal particle dispersion, (II) A step of adding an aqueous solution of salt to the metal particle dispersion to obtain a phase separated into a hydrophilic phase and a hydrophobic solvent phase, (III) A step of coating the surface of the metal particles with a polysiloxane compound while the phase-separated phase is in a phase-separated state, A method for producing a metal pigment composition characterized by containing the following: <Metal particles> In this embodiment, it is preferable to use base metal particles such as aluminum, titanium, zinc, iron, magnesium, copper, nickel, and chromium, as well as alloys thereof. Of these, aluminum, titanium, nickel, and chromium are more preferable, and aluminum is particularly preferred. The metal particles preferably have an average particle size (d50) of 2 to 20 μm and an average thickness (t) in the range of 0.001 to 1 μm, and more preferably in the range of 0.01 to 0.8 μm. The metal particles used as pigments are not particularly limited, but flaky particles are preferred. The average particle size (d50) of the metal particles can be measured in the same manner as described below for the average particle size (d50) of the coated particles contained in the aluminum pigment composition in the examples. The average thickness (t) of metal particles can be calculated from the water surface diffusion area and density of the particles. The water surface diffusion area refers to the area occupied by a unit mass of dry composite particles when they are uniformly diffused on the water surface using the leafing phenomenon, covering the surface without gaps. The water surface diffusion area can be measured in accordance with the provisions of JIS K5906:1998. Particularly suitable are aluminum flakes, which are widely used as metallic pigments. The aluminum flakes used in this invention are those that have the surface properties, particle size, and shape required for metallic pigments, such as surface gloss, whiteness, and brilliance. Aluminum flakes are usually sold commercially in paste form and can be used as is, or the surface fatty acids may be removed beforehand using an organic solvent. Powdered aluminum flakes are generally obtained by grinding atomized aluminum powder and/or aluminum foil using methods commonly used in the pigment industry, such as the dry ball mill method, wet ball mill method, attritor method, and stamp mill method, in the presence of grinding aids and inert solvents to form so-called flakes. After this process, they are further obtained by performing necessary steps such as sieving (classification), filtration, washing, and mixing. In another embodiment, so-called aluminum vapor-deposited foil with an average particle size (d50) of 3 to 30 μm and an average thickness (t) of 5 to 50 nm can also be used. <Silicon-containing compounds> In this embodiment, the silicon-containing compound used as a raw m