Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/03—Powdery paints
  • C09D5/032—Powdery paints characterised by a special effect of the produced film, e.g. wrinkle, pearlescence, matt finish
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C3/00—Treatment in general of inorganic materials, other than fibrous fillers, to enhance their pigmenting or filling properties
  • C09C3/10—Treatment with macromolecular organic compounds
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/40—Additives
  • C09D7/60—Additives non-macromolecular
  • C09D7/61—Additives non-macromolecular inorganic
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/40—Additives
  • C09D7/66—Additives characterised by particle size
  • C09D7/67—Particle size smaller than 100 nm
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/40—Additives
  • C09D7/70—Additives characterised by shape, e.g. fibres, flakes or microspheres
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/80—Processes for incorporating ingredients
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/20—Particle morphology extending in two dimensions, e.g. plate-like
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/12—Surface area
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/60—Optical properties, e.g. expressed in CIELAB-values
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/08—Metals

Definitions

• the present invention relates to a method for producing a powder coating composition containing a thermosetting resin powder having a flaky pigment bonded to its surface.
• the coating film characteristics are good when no flake pigment is contained, and there is no particular problem.
• a flaky pigment is contained, there are problems as described below.
• Patent Document 1 Japanese Patent Laid-Open No. 51-137725
• Patent Document 2 Japanese Patent Laid-Open No. 50-034642
• Patent Document 4 International Publication No. 2002/0994950
• the surface of the metal pigment is a resin-coated flaky pigment
• the charge rate of the flaky pigment differs from that of the resin powder, so that a separation phenomenon between the resin powder and the flaky pigment occurs during coating.
• the design of the coating film is lowered, and the pigment content before and after the coating of the powder paint changes, so the color changes when the paint is collected and reused, making it virtually impossible to recycle the paint. become.
• uneven distribution of the resin powder and the flaky pigment occurs during coating, and color unevenness is likely to occur.
• the powder paint containing the flake pigment The bonded method is the most excellent as a form of.
• how to form a bonded structure becomes a problem.
• a method for forming a bonded structure a method in which a flaky pigment is adhered to the surface of the resin powder by a brush polisher, or a surface of the resin powder is brought into contact with a dispersion medium such as an alumina ball coated with the flaky pigment.
• the resin powder and the flaky pigment are dispersed by a three-dimensional rotary mixer or the like while applying a temperature around the melting point of the resin powder while transferring the flaky pigment to the resin.
• a method of fusing and a method of attaching a flaky pigment to the surface of a resin powder using a binder are known.
• the method using a binder has a high bonding rate between the flaky pigment and the resin powder, and has a feature that it is difficult to form an agglomerate between the flaky pigment and the resin powder in the production process, and is particularly excellent. This is considered to be a formation method (Patent Document 4).
• the flake pigment is a fine particle having an average particle diameter of 10 ⁇ m or less or a very thin flake pigment having an average thickness of 60 nm or less.
• the metallic color of the plating tone is to be applied by the dry blend method, the surface of the flake pigment is coated with a resin when a metal pigment is used for the flake pigment due to the problem of the dry blend method described above. There is a need.
• the present invention has been made in view of such a situation, and an object of the present invention is to provide a powder coating material containing a flake pigment having a specific shape suitable for developing a metallic color with a plating tone. It is providing the method which can manufacture a composition suitably.
• the present inventor has conducted extensive studies to solve the above-described problems, and as a result, the flake pigment having a shape suitable for developing a metallic color with a plating tone is very easily aggregated during drying. On the contrary, the inventors have found that flake pigments can be bound to the surface of the resin powder by utilizing this characteristic. As a result of further earnest research based on this knowledge, the flake pigment is dispersed in a volatile solvent that does not dissolve the resin powder, the dispersion is mixed with the resin powder, and the solvent is volatilized and removed while stirring. And found that a suitable powder coating composition can be produced, and finally completed the present invention.
• the present invention is a method for producing a powder coating composition
• a powder coating composition comprising a thermosetting resin powder having a flake pigment bonded to the surface thereof, and has a mean particle diameter of 10 ⁇ m or less or a flake shape having an average thickness of 60 nm or less.
• a first step of preparing a pigment a second step of obtaining a dispersion by dispersing the flaky pigment in a solvent that does not dissolve the thermosetting resin powder; and the thermosetting resin powder and the dispersion. It includes a third step of obtaining a mixture by mixing, and a fourth step of volatilizing and removing the solvent while stirring the mixture.
• the mixture is preferably stirred in the range of ⁇ 5 ° C. to 50 ° C., and the third step and the fourth step can be performed simultaneously.
• the flake pigment is preferably prepared in a paste state in which the flake pigment is dispersed in an organic solvent.
• the solvent that does not dissolve the thermosetting resin powder preferably has a boiling point in the range of 28 to 130 ° C. under atmospheric pressure, and the flake pigment is preferably aluminum flakes.
• the present invention also relates to a powder coating composition obtained by any one of the above production methods.
• the method for producing a powder coating composition of the present invention has the above-described configuration, thereby preventing the flake pigments from agglomerating, and the characteristics required as a powder coating composition (for example, excellent recyclability, It is possible to provide a powder coating composition which has less danger, hardly causes color unevenness, and has a characteristic that a coating film can have a metallic feeling, a glittering feeling, luminance, and the like. In particular, when a metal pigment such as aluminum flake is used as the flake pigment, the produced powder coating composition can give an excellent plating-like metallic color.
• the present invention relates to a method for producing a powder coating composition.
• the powder coating composition produced by the production method of the present invention includes a thermosetting resin powder in which a flaky pigment having a specific shape is bonded to the surface thereof.
• the powder coating composition of the present invention may contain other components as long as such a flaky pigment contains a thermosetting resin powder bonded to the surface thereof. Examples of such other components include various additives added to this type of powder coating composition.
• thermosetting resin powder having flake pigments bonded to its surface typically refers to a form in which a plurality of flake pigments are bonded to the surface of one thermosetting resin powder. It can be clearly distinguished from a form in which a plurality of thermosetting resin powders are bonded to the surface of a flake pigment as seen in FIG. However, it does not depart from the scope of the present invention even if a plurality of thermosetting resin powders are combined or a thermosetting resin powder in which only one flake pigment is bonded to the surface is included.
• the powder coating composition of the present invention when a metal pigment such as aluminum flakes is included as a flaky pigment having a specific shape, the powder coating composition has a particularly excellent plating-like metallic color. It will be colored.
• the flaky pigment contained in the powder coating composition of the present invention has an average particle diameter of 10 ⁇ m or less or an average thickness of 60 nm or less.
• the flake pigment having such a shape has a characteristic that it tends to agglomerate when trying to obtain individual flake pigments in a powder state, so that it has been difficult to obtain a powder coating composition in the past. Is.
• the flake pigment having such a shape is a metal pigment
• it is particularly suitable for developing a metallic color with a plating tone.
• metal pigments include metal flakes such as aluminum, zinc, copper, bronze, nickel, titanium, stainless steel, and alloy flakes thereof.
• aluminum flakes are particularly suitable because they are excellent in metallic luster, inexpensive and easy to handle because of their low specific gravity.
• the average particle size of the flaky pigment suitable for developing a metallic color with a plating tone is preferably 10 ⁇ m or less, and more preferably 8 ⁇ m or less.
• the lower limit of the average particle diameter is not particularly limited, but the lower limit is usually 2 ⁇ m or more from various manufacturing conditions.
• the average thickness is preferably 60 nm or less, and more preferably 40 nm or less.
• the lower limit of the average thickness is not particularly limited, but the lower limit is usually 15 nm or more due to various manufacturing conditions.
• the flaky pigment made of the above metal pigment may have a surface coated with a resin or the like.
• the coating amount is preferably 5 g or less per 100 g of flaky pigment. If the coating amount exceeds 5 g, it is not preferable because even if it has the above average particle diameter or average thickness, it tends to not exhibit a metallic color in a plating tone.
• the flaky pigment (metal pigment) whose surface is coated with a resin or the like is preferable because it can avoid the risk of sparking between electrodes applied with a high voltage during corona powder coating.
• a grinding aid added at the time of grinding may be adsorbed on the surface of such a metal pigment.
• grinding aids include fatty acids (oleic acid, stearic acid), aliphatic amines, aliphatic amides, aliphatic alcohols, ester compounds, and the like.
• fatty acids oleic acid, stearic acid
• aliphatic amines aliphatic amides
• aliphatic alcohols aliphatic alcohols
• ester compounds and the like.
• the adsorbing amount of such grinding aid is preferably less than 2 parts by mass with respect to 100 parts by mass of the metal pigment. In the case of 2 parts by mass or more, the surface gloss may be lowered.
• stearic acid as a grinding aid
• flake pigments metal pigments
• aluminum flakes with stearic acid adsorbed on the surface are also called leafing aluminum, and have the property of easily floating at the interface with the air phase during coating formation. It is particularly suitable for developing a metallic tone color.
• a flake pigment a flake shape produced by a vapor deposition method in which flake pieces are obtained by vapor-depositing a metal or the like on the substrate surface in addition to the metal pigment as described above and then peeling off from the substrate.
• Pigments can also be suitably used. In this case, a very thin flake pigment is obtained.
• examples of the flaky pigment used in the present invention include mica, surface colored mica, glass flake, surface colored glass flake, pearl and the like.
• flaky pigment of the present invention those exemplified above can be used alone, and two or more kinds can be used in combination.
• the average particle size of the flaky pigment of the present invention is obtained by calculating the volume average from the particle size distribution measured by a known particle size distribution measurement method such as laser diffraction method, micromesh sieve method, Coulter counter method or the like. Moreover, about the measurement of average thickness, a different method is employ
• the former does not know the thickness of each flake pigment, but the accuracy of the average thickness as a whole is high, and the measurement is simple.
• this former method cannot be used for flake pigments that are very thin because flake pigments aggregate.
• the latter can accurately measure even a very thin film thickness.
• the measured value is data for each flake pigment, at least 10 sheets or more are required for the average representing the whole. It must be measured and measurement is not convenient.
• the aluminum paste containing aluminum flakes or powdered aluminum flakes is washed with acetone and then the mass w (g) of the dried aluminum flakes is measured. Then, the surface area A (cm 2 ) of the water surface when the aluminum flakes are floated uniformly on the surface of the water is measured, and WCA (water surface diffusion covering area) is calculated from the following equation 1. Next, the average thickness of the aluminum flake particles is calculated by substituting the WCA value thus calculated into the following formula 2.
• such a flake pigment can be used at a blending ratio of usually about 0.05 to 5 parts by mass, more preferably 0.1 to 3 parts by mass per 100 parts by mass of the thermosetting resin powder. If the flaky pigment is less than 0.05 parts by mass, a sufficient metallic feeling and glitter may not be obtained, and it is necessary to increase the coating thickness in order to conceal the substrate. When the amount exceeds 5 parts by mass, the sharpness of the plating tone is lost and the color tone becomes white and the smoothness of the coating film is lost, and the appearance tends to deteriorate.
• thermosetting resin powder Any thermosetting resin powder can be used in the present invention as long as it is known as a powder coating resin of this kind of powder coating composition. Therefore, the “thermosetting resin powder” in the present invention is a composite powder of a thermoplastic resin having a property of being cured under application of heat by blending a thermoplastic resin with a curing agent or a crosslinking agent. That means.
• thermosetting resin powder for example, an acrylic resin-based resin and a polyester resin-based resin can be particularly preferable.
• polyester resin type include those cured with an epoxy resin, those cured with an isocyanate (urethane type), and those cured with a primid (primid type).
• thermosetting resin powder each of the resins exemplified above can be used alone, and two or more kinds thereof can be used in combination.
• the thermosetting resin powder of the present invention contains a curing agent (crosslinking agent).
• the curing agent is not particularly limited, and known or commercially available products can be used.
• a hardening accelerator can also be used together suitably.
• a dispersant or the like may be added.
• Such a dispersant is not particularly limited, and known or commercially available products can be used.
• phosphates, amines, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, and the like can be used.
• a publicly known surfactant etc. can be mentioned.
• the thermosetting resin powder of the present invention can also contain various colorants.
• colorants include quinacridone, diketopyrrolopyrrole, isoindolinone, indanthrone, perylene, perinone, anthraquinone, dioxazine, benzimidazolone, triphenylmethanequinophthalone, anthrapyrimidine, chrome lead, phthalocyanine, halogen Phthalocyanines, azo pigments (azomethine metal complexes, condensed azo, etc.), titanium oxide, carbon black, iron oxide, copper phthalocyanine, condensed polycyclic pigments, and the like.
• the blending amount of these colorants varies depending on the type, it is desirable to set the colorant within a range that does not impair the effects brought about by the flake pigment of the present invention and does not impair the smoothness of the coating film surface.
• thermosetting resin powder of the present invention may contain the following additives as required in addition to the various additive components listed above.
• additives include various fillers such as bentonite, alumina white, calcium carbonate, barium sulfate and talc, various fluidity modifiers such as silica, alumina and aluminum hydroxide, various streams such as acrylic oligomers and silicones.
• fluidity modifiers such as silica, alumina and aluminum hydroxide
• various streams such as acrylic oligomers and silicones.
• examples thereof include spreading agents, various antifoaming agents such as benzoin, waxes, coupling agents, antioxidants, magnetic powders, stabilizers, ultraviolet absorbers, leveling agents, thickeners, and antisettling agents.
• the thermosetting resin powder of the present invention can contain various additives and various functional materials as described above.
• the average particle diameter of such a thermosetting resin powder is not particularly limited, but is usually preferably about 5 to 100 ⁇ m, and particularly preferably 15 to 60 ⁇ m.
• the average particle size is less than 5 ⁇ m, it becomes difficult to uniformly mix with the flaky pigment, and the tendency of the thermosetting resin powders to agglomerate is high, and it may not be possible to uniformly dust during powder coating. .
• an average particle diameter exceeds 100 micrometers, the smoothness of the coating-film surface may be inhibited and a favorable external appearance may not be obtained.
• Such an average particle diameter can be determined by a known particle size distribution measurement method such as a laser diffraction method, a micromesh sieve method, or a Coulter counter method.
• thermosetting resin powder for example, various additives such as a resin, a curing agent, and a filler to be added as necessary are prepared as raw materials, and these raw materials are first mixed with a mixer or a blender. Dry blend using a mixer. After dry blending, the raw materials are melt-kneaded with a kneader and cooled.
• the thermosetting resin powder of the present invention can be obtained by pulverizing the cooled melt-kneaded product using a machine or an airflow type pulverizer, and then classifying using an airflow type classifier. .
• the thermosetting resin powder can be produced by, for example, a spray drying method or a polymerization method.
• the method for producing the powder coating composition of the present invention includes the first step of preparing a flake pigment having an average particle diameter of 10 ⁇ m or less or an average thickness of 60 nm or less, and the above-described solvent in a solvent that does not dissolve the thermosetting resin powder.
• a second step of obtaining a dispersion by dispersing the flaky pigment a third step of obtaining a mixture by mixing the thermosetting resin powder and the dispersion, and the solvent while stirring the mixture.
• a fourth step of removing by volatilization is removing by volatilization.
• the method for producing a powder coating composition of the present invention may include other steps as long as it includes the first to fourth steps.
• the first step of the present invention is a step of preparing a flake pigment having an average particle size of 10 ⁇ m or less or an average thickness of 60 nm or less.
• Flake pigments typified by aluminum flakes are rarely handled as dry powders as industrial products, and are generally handled in a paste state in which flake pigments are dispersed in an organic solvent. For this reason, it is preferable that the 1st process of this invention prepares a flaky pigment in the paste state by which the flaky pigment was disperse
• the present invention is not limited to this, and the flake pigment can be prepared as a powder as long as the flake pigment does not aggregate.
• such a flaky pigment in a paste state can be used as it is in the second step described later.
• such pasty flake pigments are made into a paste state using mineral spirit, toluene, ethyl acetate, butyl acetate, isoparaffin, etc. as organic solvents.
• the thermosetting resin powder used in the present invention is dissolved or swollen. Therefore, when preparing the flaky pigment in a paste state, the organic solvent is replaced with a solvent used in the second step in order to reduce the influence of the organic solvent before performing the second step described later. It is preferable to make it.
• a solvent replacement method for example, a paste containing such an organic solvent and flake pigment (that is, a commercially available paste-like flake pigment) is washed with the solvent used in the second step using a filtration device. And a method of recovering the flaky pigment in a state of being dispersed in the solvent used in the second step by filtering or centrifuging the paste after being dispersed in the solvent used in the second step. Can be mentioned.
• the first step of the present invention includes such a solvent replacement step.
• the second step of the present invention is a step of obtaining a dispersion by dispersing the flaky pigment prepared in the first step in a solvent that does not dissolve the thermosetting resin powder used in the present invention.
• the solvent used in the second step is not particularly limited as long as the solvent does not dissolve the thermosetting resin powder used in the present invention.
• “does not dissolve the thermosetting resin powder” means that the thermosetting resin powder does not have a property of dissolving or swelling, and that this characteristic is defined by a numerical value. Although it is difficult, such a characteristic is usually exhibited if the solubility parameter is 8.2 or less.
• the solvent that does not dissolve the thermosetting resin powder preferably has a low boiling point.
• the thermosetting resin powder for powder coating melts at 50 to 80 ° C., it preferably has a low boiling point so that it can be distilled below the melting temperature.
• the fourth step described later is carried out under vacuum at a temperature in the range of ⁇ 5 ° C. to 50 ° C., more preferably in the range of 0 ° C. to 30 ° C. It is particularly desirable that it can be removed.
• the solvent meeting the above conditions is preferably a solvent having a boiling point in a specific range under atmospheric pressure. That is, this boiling point is preferably 28 ° C. or higher, and particularly preferably 60 ° C. or higher.
• the boiling point is preferably 130 ° C. or lower, and particularly preferably 110 ° C. or lower.
• Examples of such a solvent include linear alkanes such as pentane, hexane, heptane and octane, and isoparaffins such as isopentane, isohexane, isoheptane and isooctane.
• linear alkanes such as pentane, hexane, heptane and octane
• isoparaffins such as isopentane, isohexane, isoheptane and isooctane.
• the concentration of the flaky pigment in the dispersion obtained in the second step is preferably 1 to 35% by mass, but this value is inevitably linked to the appropriate amount of solvent used in the next third and fourth steps. Is stipulated.
• the type of flake pigment contained in the final product powder coating composition and the ratio of the flake pigment to the thermosetting resin powder are determined. For example, in a combination of a certain flake pigment and a thermosetting resin powder, it is assumed that the optimum flake pigment concentration is 1 g of flake pigment with respect to 100 g of the thermosetting resin powder. In this case, an appropriate content range of the solvent in the third step and the fourth step will be described later, but for convenience, it is assumed that the solid content concentration is 91%.
• Solid content concentration (%) (thermosetting resin powder mass + flaked pigment mass) / (thermosetting resin powder mass + flaked pigment mass + solvent mass) ⁇ 100
• 1 g of flaky pigment and 10 g of solvent may be mixed with 100 g of the thermosetting resin powder. That is, the dispersion liquid prepared in the second step is defined at a ratio of 10 g of solvent to 1 g of flake pigment, and the concentration of the flake pigment is 9.1%.
• the flaky pigment prepared in the first step is in a paste state and the flaky pigment concentration in the paste is 50%
• a dispersion may be prepared at a ratio of 9 g of solvent to 2 g of this paste. It will be.
• the third step of the present invention is a step of obtaining a mixture by mixing the dispersion obtained in the second step and the thermosetting resin powder. More specifically, this step is preferably a step of obtaining a mixture by adding and kneading the dispersion obtained above to the thermosetting resin powder.
• the mixture is preferably a uniform mixture of thermosetting resin powder and dispersion.
• the dispersion may be added all at once, or may be added in a plurality of times.
• the method of addition is not particularly limited, but in industrial production, it is preferable to spray and add the dispersion to the thermosetting resin powder while stirring the powder. This is because the dispersion and the thermosetting resin powder can be mixed uniformly.
• Such a third step is preferably performed under atmospheric pressure.
• thermosetting resin powder When thermosetting resin powder is added to the above dispersion, the dispersion first adheres to the inner wall of the mixing and stirring tank, and there is a clearance between the stirring blade and the inner wall, so uniform mixing and stirring of the dispersion is difficult. It is not preferable.
• the solid content concentration of the mixture is preferably 50 to 98% by mass, and more preferably 70 to 95% by mass.
• solid content concentration exceeds 98 mass%, uniform mixing with a flaky pigment and a thermosetting resin powder may become difficult.
• solid content concentration is less than 50%, much time and energy are needed for the volatilization removal of the solvent in the below-mentioned 4th process.
• Examples of the apparatus that can be used for mixing in the third step include a reverse cone type ribbon mixing and stirring apparatus, an atmospheric pressure kneader mixer, a twin screw type kneader, a Henschel mixer, a high speed mixer such as a super mixer, and a blender. Etc. can be used.
• the fourth step of the present invention is a step of volatilizing and removing the solvent while stirring the mixture obtained in the third step.
• stirring should be understood as a term having a broad concept including actions such as “kneading”.
• thermosetting resin powders do not block
• thermosetting resin powder itself is not self-aggregating from the above average particle diameter. Furthermore, the shape is an indeterminate shape like pulverized glass, so that the contact between the thermosetting resin powders is a point contact or a line contact. Therefore, the thermosetting resin powders do not block each other because the mixing and stirring is continued even during the solvent removal, and the bonding by point contact or line contact between the thermosetting resin powders from the outside by stirring or the like. It is because it peels immediately by physical force.
• the contact between the flaky pigment and the thermosetting resin powder is considered to be a surface contact and easily exhibits an aggregating effect, so that the flaky pigment is bound on the thermosetting resin powder.
• the details of the mode of bonding between such flaky pigment and the thermosetting resin powder are unknown, it is probably considered to be van der Waals bonding.
• the solvent is volatilized and removed while vacuum suction.
• the above mixture is preferably stirred in the range of ⁇ 5 ° C. to 50 ° C.
• bonding of thermosetting resin powder is accelerated
• the agglomerated particles (blocked particles) can be pulverized by a physical pulverization method such as a jet mill.
• the flaky pigment is peeled off from the surface of the thermosetting resin powder along with the work, and spreads. In this case, the thermosetting resin powder particles themselves may be destroyed.
• the temperature is lower than ⁇ 5 ° C., it takes a long time to volatilize the solvent, which is not practical. That is, the fourth step of the present invention is a temperature at which the thermosetting resin powders do not block each other (that is, a temperature lower than the melting temperature of the thermosetting resin powder), and the solvent is efficiently volatilized. It is preferred to run at temperature.
• the third step and the fourth step can be continuously performed in the same apparatus such as an inverted conical ribbon mixing mixer and a vacuum kneader mixer. Also, the third step and the fourth step are carried out simultaneously, that is, the thermosetting resin powder and the dispersion are mixed with stirring, and simultaneously the solvent is sequentially volatilized and removed from the mixture. Is also possible. However, it is preferable to perform the third step and the fourth step as separate steps because the productivity can be improved.
• the device used in the third step can be used as it is, and the third step is completed regardless of which device is used.
• the solvent can be volatilized and removed by continuing stirring at a later time and preferably performing vacuum suction.
• the mixture is once taken out from the apparatus, and then the mixture is again put into a dryer such as a vibration dryer or a continuous fluid dryer, thereby executing the fourth step.
• a dryer such as a vibration dryer or a continuous fluid dryer
• the present invention also relates to a powder coating composition obtained by the production method as described above.
• a method of coating such a powder coating composition the powder coating composition is adhered to a material to be coated (base material) subjected to a known treatment such as a chemical conversion treatment after blasting the coating surface in advance. It is preferable to heat cure after that.
• the material to be coated is not particularly limited, but is preferably a material that does not undergo deformation or alteration due to heat curing (baking).
• known metals such as iron, copper, aluminum, and titanium, and various alloys are preferable.
• it can be used for a vehicle body, office supplies, household goods, sports equipment, building materials, electrical products, and the like.
• electrostatic powder coating method As a method of adhering the powder coating composition of the present invention to the substrate surface, for example, fluid dipping method, electrostatic powder coating method and the like can be applied, but electrostatic powder coating method is excellent in coating efficiency, More preferred.
• electrostatic powder coating method a known method such as a corona discharge method or a friction charging method can be used.
• the temperature for the heat curing can be appropriately set according to the type of the thermosetting resin powder to be used, but is usually 120 ° C. or higher, preferably 150 to 230 ° C.
• the heating time can be appropriately selected depending on the heating temperature, but it is generally 1 minute or longer, preferably 5 to 30 minutes.
• the thickness of the coating film formed by heating is not limited, but is usually about 20 to 100 ⁇ m.
• the expression of the plating-like metallic color of the coating film can be evaluated by gloss (gloss).
• a cylindrical metal container bottom 40 mm ⁇ , height 50 mm
• a cylindrical metal container bottom 40 mm ⁇ , height 50 mm
• about 5 g of a flaky pigment-containing paste as a sample is collected in the cylindrical metal container, and the collected amount is precisely weighed.
• about 20 ml of mineral spirit is further added to the cylindrical metal container to disperse the flaky pigment, and then the cylindrical metal container is placed on a 300 ° C. sand bath to completely evaporate the solvent (about 20 minutes). .
• the mass of this cylindrical metal container was measured again, and the heating residue was measured from the following formula.
• Heated residue (%) (mass of cylindrical metal container after heating ⁇ mass of cylindrical metal container) / sample mass ⁇ 100 ⁇ Measuring method of average particle diameter (D50)>
• An ethanol-based solvent (GS Arco EP-7 manufactured by Gordo Co., Ltd.) was used as the solvent, and the average particle size (D50) was measured using Microtrac 9320 X-200 manufactured by Honeywell.
• the sample is a flaky pigment-containing paste, about 0.5 g of the sample is dispersed in toluene, and the dispersion is dropped into a measurement tank (filled with the above ethanol solvent) and dispersed with ultrasonic waves (40 W for 30 seconds). ), The average particle size (D50) was measured.
• the sample was in a powder state, about 0.5 g of the sample was dispersed in the above ethanol solvent, and the average particle size (D50) was measured.
• thermosetting resin powder used in Examples and Comparative Examples of the present invention is polyester resin powder (Teodur PE 785-900 clear manufactured by Takashi Kubo Paint Co., Ltd.).
• thermosetting resin powder in which the flaky pigment is bonded to the surface thereof is called “bonded”, but there has been little discussion about the bonding rate between the thermosetting resin powder and the flaky pigment.
• This bond rate can be conceptually expressed as a dry blend when the bond rate is 0% and an ideal bond when the bond rate is 100%.
• this bonding rate decreases, the problems of the dry blend method described above are manifested.
• the bonding rate between the thermosetting resin powder and the flaky pigment was measured as follows.
• this measurement method utilizes the difference in shape between “flakes” and “particulates”. That is, it is assumed that the thermosetting resin powder having the flake pigment bonded to the surface thereof is regarded as “particulate”, and the free flake pigment is regarded as “flaked”. Then, the coupling rate is approximately measured by utilizing the characteristic derived from the difference in shape between the two, that is, the difference in the adhesion rate to the paper surface.
• the measurement method is based on the following assumptions.
• the contact between the paper surface (flat surface) and the “particulate” object is regarded as a point contact, and the “particulate” object has a sufficient mass. “Assuming the object peels easily.
• the “flaked” object is flake shaped, it is assumed that it adheres to the paper surface even after vibration is applied because it is in surface contact with the paper surface and has a small volume and a small mass.
• the black art paper is vibrated and the sample is screened off. This makes it possible to separate a “flaky” object from a “particulate” object. That is, the “flaky” object remains on the paper surface while adhering to the paper surface, and the “particulate” object is peeled off from the paper surface, so that they are separated.
• the flake pigment which is a “flaky” object attached on black art paper
• the flake pigment has a silver color, so if you observe the color, visually observe the adhesion state You can check it easily.
• the stronger the color of silver the greater the amount of flake pigment adhering to the black art paper, that is, the lower the binding rate.
• the lower the flake pigment adhering to the black art paper the weaker the silver color is), the higher the binding rate is.
• the bonding state is good (evaluation “A” in Table 1), and if there is a little flake pigment adhering to black art paper, the bonding state is incomplete ( “B”), if there were many flake pigments adhering to the black art paper, it was evaluated that the bonding state was poor (“C”).
• ⁇ Powder coating method> Using a corona discharge electrostatic powder coating machine (trade name “MXR-100VT-mini”, manufactured by Asahi Sunac Co., Ltd.), the powder coating composition is applied to a standard test plate (manufactured by Nippon Test Panel Co., Ltd.) with an applied voltage of 80 kV. Bonded steel plate (100 ⁇ 200 mm) was applied and baked at 190 ° C. for 20 minutes to prepare a coated plate.
• a corona discharge electrostatic powder coating machine trade name “MXR-100VT-mini”, manufactured by Asahi Sunac Co., Ltd.
• ⁇ Gloss measurement method> Using a gloss meter (Gloss Meter TC-108DP / A manufactured by Tokyo Denshoku Co., Ltd.), irradiate light at an angle of 60 ° with respect to the normal of the coated plate, and measure the gloss (gloss) by receiving light at the regular reflection position.
• the metallic color of the plating tone was evaluated. In Table 1, it is described as “Gloss”, and the higher the numerical value, the better the metallic color of the plating tone.
• the state in which the observer's face is projected on the coating plate and the eyes, nose, mouth, etc. of the observer can be discriminated is “A”
• the state in which the contour of the observer's face can be discriminated but the eyes and nose cannot be discriminated is “B”
• a state where even the contour of the observer's face could not be discriminated was evaluated as “C”.
• the evaluation results are shown in Table 1.
• Example 1 An aluminum paste (trade name: 0670TS) manufactured by Toyo Aluminum Co., Ltd. was prepared as a flaky pigment in a paste state (including aluminum flakes as a flaky pigment). 50 g of this pasty flaky pigment was dispersed in 280 g of normal heptane (boiling point 98.4 ° C.), and centrifuged at 3000 rpm for 20 minutes in a centrifuge (H-38F manufactured by Kokusan Co., Ltd.).
• the obtained precipitate was a paste-like flaky pigment which was solvent-substituted with normal heptane, the heating residue was 65.1%, the average particle size (D50) of the flaky pigment was 4.7 ⁇ m, and the average The thickness was 60 nm (above “first step”).
• “0670TS” is a type called leafing type, and stearic acid is adsorbed on the surface.
• a paste-like flaky pigment (aluminum paste solvent-substituted with normal heptane) prepared as described above is dispersed in 20 g of normal heptane (a solvent that does not dissolve thermosetting resin powder).
• normal heptane a solvent that does not dissolve thermosetting resin powder.
• thermosetting resin powder (trade name: Teodur PE 785-900 clear), and the mixture was obtained by thoroughly mixing and stirring (third step).
• the normal heptane was naturally evaporated while continuing kneading (stirring). This evaporation operation was performed until the fluidity peculiar to the dry powder returned, and was dried until sufficient fluidity was obtained. Thereafter, the mixture was put into a 1 liter eggplant-shaped flask, and normal heptane was completely volatilized and removed under vacuum (normal temperature of about 20 ° C.) in an evaporator while rotating and stirring (fourth step, this fourth step). For about 20 minutes). The obtained powder was sieved with a screen having an opening of 100 ⁇ m to obtain a powder coating composition of the present invention, which was used as a sample.
• Example 2 Example 1 except that Toyo Aluminum Co., Ltd. aluminum paste (trade name: 0231E-N) was used instead of Toyo Aluminum Co., Ltd. aluminum paste (trade name: 0670TS) used in Example 1.
• a paste-like flaky pigment (aluminum flakes) which was solvent-substituted with normal heptane was prepared.
• the paste-like flaky pigment had a heating residue of 71.3%, the flaky pigment had an average particle diameter (D50) of 7.2 ⁇ m, and an average thickness of 130 nm.
• D50 average particle diameter
• “0231E-N” is also a leafing type and has stearic acid adsorbed on its surface.
• Example 3 Aluminum paste (trade name: Metacene 71-0010, heating residue: 10%) manufactured by Toyo Aluminum Co., Ltd. was prepared as a paste-like flake pigment (containing aluminum flake as a flake pigment). 500 g of normal heptane was added to and dispersed in 198.3 g of this pasty flake pigment. Subsequently, the same centrifugal separation operation as in Example 1 was performed to obtain a precipitate, and 300 g of normal heptane was further added to the precipitate and redispersed.
• the paste-like flake pigment had a heating residue of 38.7%, the flake pigment had an average particle diameter (D50) of 12.9 ⁇ m, and an average thickness of 25 nm.
• D50 average particle diameter
• Methodacene 71-0010 is a product manufactured by an aluminum vapor deposition method, and stearic acid is not adsorbed on the surface.
• Example 4 The flake pigment (aluminum flakes, hereinafter also referred to as “deposited aluminum”) contained in the aluminum paste by the vapor deposition method used in Example 3 was leafed using the surface treatment agent described in International Publication No. 2005/007755 pamphlet.
• the powder coating composition of the present invention was prepared in the same manner as in each of the above examples using the flaky pigment used in the present invention.
• Example 2 Next, stirring was continued at 75 ° C. for 1 hour, so that the surface treatment agent was adsorbed on the surface of the vapor-deposited aluminum which was a flaky pigment. Thereafter, the same centrifugal separation operation as in Example 1 was carried out to obtain a paste in which the leaf-like flaky pigment was dispersed in ethyl acetate. The heating residue of the paste was measured and found to be 29.1%.
• a paste-like flaky pigment (aluminum paste solvent-substituted with normal heptane) prepared as described above is dispersed in 20 g of normal heptane (a solvent that does not dissolve thermosetting resin powder).
• normal heptane a solvent that does not dissolve thermosetting resin powder.
• a powder coating composition was obtained by adding 0.6 g of the above powder to 100 g of the same thermosetting resin powder as used in Example 1 and performing dry blending. That is, this powder coating composition corresponds to a dry blend by a conventional dry blend method.
• Example 1 0.6 g of the powdery flaky pigment obtained in Comparative Example 1 and 100 g of the same thermosetting resin powder used in Example 1 are mixed to obtain a dry blend. It was. A binder (trade name: YS Polystar TH-130, manufactured by Yasuhara Chemical Co., Ltd.) (1.5 g) was dissolved in 20 g of normal heptane, and this solution was added to the dry blend obtained above and mixed well. Subsequently, the same operation as in the fourth step of Example 1 was performed to obtain a powder coating composition.
• a binder trade name: YS Polystar TH-130, manufactured by Yasuhara Chemical Co., Ltd.
• Example 1 As described above, even when the powder coating composition was used, it was possible to develop a metallic color with a plating tone as a result. However, the drying process, the screen process, and the dry blend process were further performed with respect to Example 1. As a result, the manufacturing efficiency was significantly reduced. Moreover, although the same flake pigment as in Example 1 was used, the gloss measurement result was inferior to that in Example 1.
• the product “P-0100” is also called a leafing type and has stearic acid adsorbed on its surface. This product is a powdery product obtained by industrially drying a paste. Thereafter, the same operation as in the fourth step of Example 1 was performed to obtain a powder coating composition.
• Example 3 More specifically, by first mixing 1.5 g of the powdery flaky pigment used in Comparative Example 3 and 100 g of the same thermosetting resin powder used in Example 1, a dry blend product was prepared. Obtained. 1.5 g of the same binder used in Comparative Example 2 was dissolved in 20 g of normal heptane and added to the dry blend obtained above and mixed well. Subsequently, the same operation as in the fourth step of Example 1 was performed to obtain a powder coating composition.
• the gloss measurement is also greatly affected by the smoothness of the coating film, and even if there is no pigment that reflects light, such as flake pigment, if the smoothness is high, high gloss is manifested by the reflection of the resin itself. There is a case. For this reason, the gloss when the thermosetting resin powder used in this example is applied alone is also shown as Reference Example 2. In the case where no pigment is added, the highest fluidity can be obtained at the time of baking. Therefore, since Reference Example 2 gives the maximum smoothness when a coating film is formed with the thermosetting resin powder used this time, the resin It is thought that it shows the highest value of reflection from origin.
• flake pigments (aluminum flakes) used in powder coating are coated with a resin. This is to ensure safety during electrostatic coating and chemical resistance of the paint film when used in dry blends, and to ensure chemical resistance of the paint film when used in bond. It is. Therefore, as a typical representative example of such a flake pigment, a flake pigment (aluminum flake) having a particle size called a medium particle size among the flake pigments (aluminum flakes) used for coating is resin-coated. The powder product was powder-coated with dry blend.
• thermosetting resin powder same as that used in Example 1 with 10 g of aluminum powder pigment (trade name: PCF7640A, average particle size (D50): 18.1 ⁇ m, average thickness: 400 nm) manufactured by Toyo Aluminum Co., Ltd. And dry blended. And when the gloss of the coated plate obtained by powder-coating this dry blend was measured, the gloss was 61.
• Example 2 The same thermosetting resin powder as used in Example 1 was applied alone. And when the gloss of the coating plate obtained in this way was measured, the gloss was 98. That is, it is considered that the glosses shown in the above examples and comparative examples are not significantly affected by the gloss of the resin itself and reflect the reflection of the flake pigment.

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