Classifications

• • 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
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/40—Compounds of aluminium
• • 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
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/0015—Pigments exhibiting interference colours, e.g. transparent platelets of appropriate thinness or flaky substrates, e.g. mica, bearing appropriate thin transparent coatings
  • C09C1/0018—Pigments exhibiting interference colours, e.g. transparent platelets of appropriate thinness or flaky substrates, e.g. mica, bearing appropriate thin transparent coatings uncoated and unlayered plate-like particles
• • 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
  • C09D17/00—Pigment pastes, e.g. for mixing in paints
• • 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
  • C09D7/62—Additives non-macromolecular inorganic modified by treatment with other compounds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D2202/00—Metallic substrate
  • B05D2202/10—Metallic substrate based on Fe
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D2451/00—Type of carrier, type of coating (Multilayers)
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D5/00—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures
  • B05D5/06—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain multicolour or other optical effects
  • B05D5/065—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain multicolour or other optical effects having colour interferences or colour shifts or opalescent looking, flip-flop, two tones
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
  • B05D7/50—Multilayers
  • B05D7/56—Three layers or more
  • B05D7/57—Three layers or more the last layer being a clear coat
  • B05D7/572—Three layers or more the last layer being a clear coat all layers being cured or baked together

Definitions

• the present invention relates to a photoluminescent pigment dispersion and a method for forming a multilayer coating film.
• metallic or pearlescent luster in the fields of automobile exterior panels and automobile parts (hereinafter, metallic luster and pearlescent luster will be collectively referred to as "metallic or pearlescent luster").
• Metallic or pearlescent luster is a texture that has no grainy surface like a mirror, and furthermore, when the painted plate is viewed near specular reflected light (highlights), it appears shiny, but when viewed in areas away from specular reflected light where the reflected light intensity is relatively low (shades), it appears dark; in other words, it has a texture that is characterized by a large difference in brightness between the highlight and shade areas.
• Patent Document 2 discloses an aqueous base coating composition that contains a photoluminescent pigment obtained by pulverizing a vapor-deposited metal film to produce metal flakes, and an aqueous cellulose derivative having an acid value of 20 to 150 mg KOH/g (solids), the aqueous cellulose derivative being the main binder resin, and the photoluminescent pigment content is 20 to 70 mass % in terms of PWC.
• Patent Document 3 discloses a glittering pigment dispersion that contains water, a scaly aluminum pigment, and a cellulose-based viscosity modifier, and that contains 0.1 to 10 parts by mass of solids per 100 parts by mass of all components of the glittering pigment dispersion, has a viscosity measured using a B-type viscometer within the range of 400 to 10,000 mPa ⁇ sec at a rotation speed of 6 rpm, and contains 30 to 200 parts by mass of the scaly aluminum pigment as solids per 100 parts by mass of the total amount of components other than the scaly aluminum pigment in the total solids.
• the coating film formed with the glittering pigment dispersion described in Patent Document 3 has excellent metallic luster, but wrinkles may occur at the edges, where the film thickness tends to be thicker than in general areas, and sagging may occur in vertical areas.
• the object of the present invention is to provide a glittering pigment dispersion that can form a coating film that has excellent metallic or pearlescent metallic or pearlescent luster, does not wrinkle at the edges where the film thickness tends to be thicker than in the general area, and does not sag at the vertical areas.
• the present invention encompasses the subject matter described in the following paragraphs.
• the solid content is 0.1 to 10 parts by mass relative to 100 parts by mass of the total of all components of the brilliant pigment dispersion
• the nanocellulose (C) is a phosphate group-containing nanocellulose (C1), a carboxyl group-containing nanocellulose (C2), and a sulfonic acid group-containing nanocellulose (C3).
• a glittering pigment dispersion is a phosphate group-containing nanocellulose (C1), a carboxyl group-containing nanocellulose (C2), and a sulfonic acid group-containing nanocellulose (C3).
• Item 2 The photoluminescent pigment dispersion according to Item 1, wherein the photoluminescent pigment (B) contains an aluminum pigment.
• Item 3 The photoluminescent pigment dispersion according to item 1 or 2, wherein the phosphate group-containing nanocellulose (C1) contains phosphate group-containing cellulose nanofibers (C11) and/or phosphate group-containing cellulose nanocrystals (C12).
• Item 4 The photoluminescent pigment dispersion according to any one of items 1 to 3, wherein the cellulose (C) contains a carboxyl group-containing nanocellulose (C2), and the carboxyl group-containing nanocellulose (C2) contains a carboxyl group-containing cellulose nanofiber (C21) and/or a carboxyl group-containing cellulose nanocrystal (C22).
• Item 5 The photoluminescent pigment dispersion according to any one of Items 1 to 4, wherein the cellulose (C) contains sulfonic acid group-containing nanocellulose (C3), and the sulfonic acid group-containing nanocellulose (C3) contains sulfonic acid group-containing cellulose nanofiber (C31) and/or sulfonic acid group-containing cellulose nanocrystal (C32).
• Item 6 The photoluminescent pigment dispersion according to any one of Items 1 to 5, wherein the content ratio of the phosphate group-containing nanocellulose (C1) to at least one selected from the group consisting of carboxyl group-containing nanocellulose (C2) and sulfonic acid group-containing nanocellulose (C3) is within the range of 1/99 to 50/50 in terms of the mass ratio of the phosphate group-containing nanocellulose (C1) to the at least one selected from the group consisting of carboxyl group-containing nanocellulose (C2) and sulfonic acid group-containing nanocellulose (C3).
• Step (1) A step of applying a base coating material (X) onto an object to be coated to form an uncured base coating film;
• Step (2): A step of applying the glittering pigment dispersion (Y) according to any one of Items 1 to 6 onto the base coating film formed in Step (1) to form an uncured glittering coating film;
• the present invention provides a glittering pigment dispersion that is capable of forming a coating film that has excellent metallic or pearlescent luster, does not wrinkle at the edges where the film tends to be thicker than in the general area, and does not sag at the vertical areas.
• the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of a numerical range of another stage.
• the upper or lower limit of the numerical range may be replaced with a value shown in an example or a value that can be unambiguously derived from an example.
• a numerical value connected with " ⁇ " means a numerical range that includes the numerical values before and after " ⁇ " as the upper and lower limits.
• edge portion refers to the end portion of the object to be coated.
• edge portions include the edge of the object to be coated and the corner formed by the intersection of two surfaces of the object to be coated.
• vertical portion refers to the portion that extends in a substantially vertical direction when the object to be coated is placed in a fixed position.
• general part refers to a part that does not come into contact with other components and occupies the majority of the surface area of the coated object or one of its components, such as the main body, excluding edge parts.
• the brilliant pigment dispersion of the present invention is a brilliant pigment dispersion containing a wetting agent (A), a brilliant pigment (B), nanocellulose (C) and water (D),
• the solid content is 0.1 to 10 parts by mass relative to 100 parts by mass of the total of all components of the brilliant pigment dispersion
• the nanocellulose (C) is a glittering pigment dispersion containing at least one selected from the group consisting of phosphate group-containing nanocellulose (C1), carboxyl group-containing nanocellulose (C2), and sulfonic acid group-containing nanocellulose (C3).
• the wetting agent (A) in the glittering pigment dispersion of the present invention is not particularly limited, so long as it is a material that is effective in helping to uniformly orient the glittering pigment dispersion on the substrate when the dispersion is applied to the substrate.
• wetting agents materials that have this effect may also be called wetting agents, leveling agents, surface conditioners, defoamers, surfactants, superwetters, etc.
• wetting agents include wetting agents, leveling agents, surface conditioners, defoamers, surfactants, and superwetters.
• wetting agent (A) examples include silicone wetting agents, acrylic wetting agents, vinyl wetting agents, fluorine wetting agents, and acetylene diol wetting agents.
• the above wetting agents can be used alone or in appropriate combinations of two or more.
• wetting agent (A) it is preferable to use an acetylene diol-based wetting agent and/or a wetting agent having an ethylene oxide chain, from the viewpoint of obtaining a highly stable glitter pigment dispersion and a method for forming a multilayer coating film, which have excellent water resistance and can form a metallic or pearlescent luster.
• a wetting agent (A) that is an ethylene oxide adduct of acetylene diol.
• wetting agents (A) include, for example, the Dynol series, Surfynol series, and Tego series manufactured by Evonik Industries, the BYK series manufactured by BYK-Chemie, the Granol series and Polyflow series manufactured by Kyoeisha Chemical Co., Ltd., and the Disparlon series manufactured by Kusumoto Chemical Co., Ltd.
• the content of the wetting agent (A) in the photoluminescent pigment dispersion of the present invention is preferably 1.5 to 30 parts by mass, more preferably 2 to 25 parts by mass, and even more preferably 2.5 to 20 parts by mass in terms of solid content, based on 100 parts by mass of the solid content of the photoluminescent pigment dispersion, from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster, does not develop wrinkles at edge parts where the film thickness tends to be thicker than in general parts, and does not develop sagging at vertical parts.
• glittering pigment (B) in the glittering pigment dispersion of the present invention examples include vapor-deposited metal flake pigments, aluminum flake pigments, and optical interference pigments.
• vapor-deposited metal flake pigments and aluminum flake pigments are preferred.
• optical interference pigments are preferred.
• Vapor-deposited metal flake pigments are obtained by depositing a metal film onto a base substrate, peeling off the base substrate, and then pulverizing the vapor-deposited metal film.
• Examples of the base substrate include films.
• the metal material of the metal film is not particularly limited, but examples include aluminum, gold, silver, copper, brass, titanium, chromium, nickel, nickel chromium, stainless steel, etc. Among these, aluminum or chromium is particularly preferred from the viewpoints of availability and ease of handling.
• a vapor-deposited metal flake pigment obtained by vapor-depositing aluminum is referred to as a "vapor-deposited aluminum flake pigment”
• a vapor-deposited metal flake pigment obtained by vapor-depositing chromium is referred to as a "vapor-deposited chromium flake pigment.”
• the surface of the vapor-deposited aluminum flake pigment is silica-treated from the viewpoints of storage stability and obtaining a coating film with excellent metallic luster.
• vapor-deposited aluminum flake pigment Commercially available products that can be used as the above-mentioned vapor-deposited aluminum flake pigment include, for example, the "METALURE” series (product name, manufactured by Ecart), the “Hydroshine WS” series (product name, manufactured by Ecart), the “Decomet” series (product name, manufactured by Schlenk), and the “Metasheen” series (product name, manufactured by BASF).
• vapor-deposited chrome flake pigment Commercially available products that can be used as the above-mentioned vapor-deposited chrome flake pigment include, for example, the "Metalure Liquid Black” series (product name, manufactured by Ecart Co., Ltd.).
• the average thickness of the vapor-deposited metal flake pigment is preferably 0.01 to 1.0 ⁇ m, and more preferably 0.015 to 0.1 ⁇ m.
• the average particle size (D50) of the vapor-deposited metal flake pigment is preferably 1 to 50 ⁇ m, more preferably 5 to 20 ⁇ m.
• the average particle size referred to here means the median diameter of the volume-based particle size distribution measured by the laser diffraction scattering method using a Microtrac particle size distribution measuring device MT3300 (product name, manufactured by Nikkiso Co., Ltd.).
• the thickness is defined as the average value of 100 or more measurements, measured by observing the cross section of the coating film containing the photoluminescent pigment under a microscope and measuring the thickness using image processing software.
• the average particle size is below the upper limit, no grainy feel will be produced in the multi-layer coating film, and if it is above the lower limit, the change in brightness from highlights to shades will be large.
• Aluminum flake pigments are generally produced by grinding and milling aluminum in a ball mill or attritor mill in the presence of a grinding medium using a grinding aid.
• Grinding aids used in the production process of the aluminum flake pigment include higher fatty acids such as oleic acid, stearic acid, isostearic acid, lauric acid, palmitic acid, and myristic acid, as well as aliphatic amines, aliphatic amides, and aliphatic alcohols.
• Aliphatic hydrocarbons such as mineral spirits are used as the grinding medium.
• the above aluminum flake pigments can be broadly classified into leafing type and non-leafing type depending on the type of grinding aid.
• non-leafing type aluminum pigments from the viewpoint of forming a metallic coating film that has excellent water resistance, high gloss in highlights, small particle feel, and a fine texture.
• non-leafing type aluminum pigments those with no special surface treatment can be used, but those with a resin-coated surface, those with a silica treatment, and those with a phosphoric acid, molybdic acid, or a silane coupling agent can also be used.
• Those with one of the above various surface treatments can be used, but those with multiple types of treatments can also be used.
• the above-mentioned aluminum flake pigment may be a colored aluminum pigment in which the surface of the aluminum flake pigment is coated with a colored pigment and then further coated with a resin, or in which the surface of the aluminum flake pigment is coated with a metal oxide such as iron oxide.
• the above aluminum flake pigments are preferably used with an average particle size in the range of 1 to 100 ⁇ m, from the viewpoint of forming a metallic coating film with high gloss in highlights and a fine texture with a small graininess, more preferably with an average particle size in the range of 5 to 50 ⁇ m, and particularly preferably with an average particle size in the range of 7 to 30 ⁇ m.
• the thickness is preferably in the range of 0.01 to 1.0 ⁇ m, and particularly preferably with a thickness in the range of 0.02 to 0.5 ⁇ m.
• the glittering pigment (B) in the glittering pigment dispersion of the present invention can be a combination of the vapor-deposited metal flake pigment and the aluminum flake pigment.
• the mixing ratio of the vapor-deposited metal flake pigment to the aluminum flake pigment is 9/1 to 1/9, preferably 2/8 to 8/2, by mass.
• optical interference pigment it is preferable to use an optical interference pigment in which a transparent or translucent substrate is coated with titanium oxide.
• a transparent substrate refers to a substrate that transmits at least 90% of visible light.
• a translucent substrate refers to a substrate that transmits at least 10% to less than 90% of visible light.
• a light interference pigment is a shiny pigment in which the surface of a transparent or semi-transparent, scaly substrate, such as mica, artificial mica, glass, iron oxide, aluminum oxide, or various metal oxides, is coated with a metal oxide that has a refractive index different from that of the substrate.
• a transparent or semi-transparent, scaly substrate such as mica, artificial mica, glass, iron oxide, aluminum oxide, or various metal oxides
• the metal oxide include titanium oxide and iron oxide
• light interference pigments can express a variety of different interference colors depending on the thickness of the metal oxide.
• optical interference pigments include the metal oxide-coated mica pigments, metal oxide-coated alumina flake pigments, metal oxide-coated glass flake pigments, and metal oxide-coated silica flake pigments, as shown below.
• Metal oxide-coated mica pigments are pigments that use natural or artificial mica as a substrate and have the surface of the substrate coated with metal oxide.
• Natural mica is a scaly substrate made by crushing mica ore.
• Artificial mica is synthesized by heating industrial raw materials such as SiO2 , MgO , Al2O3 , K2SiF6 , and Na2SiF6 , melting them at a high temperature of about 1500°C, and then cooling and crystallizing them . Compared to natural mica, it has fewer impurities and is uniform in size and thickness.
• artificial mica substrates include fluorine phlogopite ( KMg3AlSi3O10F2 ), potassium tetrasilicic mica ( KMg2.5AlSi4O10F2 ) , sodium tetrasilicic mica ( NaMg2.5AlSi4O10F2 ), Na taeniolite ( NaMg2LiSi4O10F2 ) , and LiNa taeniolite ( LiMg2LiSi4O10F2 ) .
• fluorine phlogopite KMg3AlSi3O10F2
• potassium tetrasilicic mica KMg2.5AlSi4O10F2
• sodium tetrasilicic mica NaMg2.5AlSi4O10F2
• NaMg2LiSi4O10F2 NaMg2LiSi4O10F2
• LiNa taeniolite LiMg2LiS
• Metal oxide-coated alumina flake pigments are pigments that use alumina flakes as a substrate, and the substrate surface is coated with metal oxide.
• Alumina flakes refer to scaly (thin) aluminum oxide, which is colorless and transparent. The alumina flakes do not need to be composed solely of aluminum oxide, and may contain oxides of other metals.
• Metal oxide-coated glass flake pigments are pigments that use flake glass as a base material, and the surface of the base material is coated with metal oxide. The smooth surface of the base material of these metal oxide-coated glass flake pigments produces strong light reflection.
• Metal oxide-coated silica flake pigments are pigments in which a scaly silica base material with a smooth surface and uniform thickness is coated with metal oxide.
• the optical interference pigment may be surface-treated to improve dispersibility, water resistance, chemical resistance, weather resistance, etc.
• optical interference pigments with an average particle size in the range of 5 to 30 ⁇ m, and especially 7 to 20 ⁇ m.
• the particle size referred to here means the median diameter of the volumetric particle size distribution measured by the laser diffraction scattering method using a Microtrac particle size distribution analyzer MT3300 (product name, manufactured by Nikkiso Co., Ltd.).
• the above-mentioned optical interference pigments with a thickness in the range of 0.05 to 1.0 ⁇ m, and especially 0.1 to 0.8 ⁇ m.
• the lustrous pigment (B) in the lustrous pigment dispersion is preferably one having an average particle size in the range of 1 to 100 ⁇ m, from the viewpoint of forming a coating film with a high gloss in highlights, a fine metallic or pearlescent luster with a small particle feel, and more preferably one having an average particle size in the range of 5 to 50 ⁇ m, and particularly preferably one having a thickness in the range of 7 to 30 ⁇ m.
• the thickness is preferably in the range of 0.01 to 1.0 ⁇ m, and particularly preferably one in the range of 0.02 to 0.5 ⁇ m.
• the content of the lustrous pigment (B) in the lustrous pigment dispersion of the present invention is preferably 5 to 80 parts by mass, more preferably 10 to 75 parts by mass, and even more preferably 15 to 70 parts by mass, based on 100 parts by mass of solids in the lustrous pigment dispersion, from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster, does not develop wrinkles at edges where the film thickness tends to be thicker than in general parts, and does not develop sagging at vertical parts.
• Nanocellulose (C) includes at least one selected from the group consisting of phosphate group-containing nanocellulose (C1), carboxyl group-containing nanocellulose (C2), and sulfonic acid group-containing nanocellulose (C3).
• Nanocellulose is a term referring to nanostructured cellulose, which is made by finely breaking down cellulose, the main component of plant cell walls, to the nano level. Specific examples include cellulose nanofibers, cellulose nanocrystals, cellulose nanowhiskers, and bacterial nanocellulose produced by bacteria.
• cellulose nanofibers are defined as compounds obtained by subjecting cellulose fibers to processes such as mechanical defibration.
• Cellulose nanocrystals are defined as compounds obtained by subjecting cellulose fibers to chemical processes such as acid hydrolysis.
• the nanocellulose can be made by defibrating cellulose raw materials.
• cellulose raw materials include plant materials (e.g., wood, bamboo, hemp, jute, kenaf, agricultural waste, cloth, pulp (softwood unbleached kraft pulp (NUKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), hardwood bleached kraft pulp (LBKP), softwood unbleached sulfite pulp (NUSP), softwood bleached sulfite pulp (NBSP), thermomechanical pulp (TMP), recycled pulp, waste paper, etc.), animal materials (e.g., sea squirts), algae, microorganisms (e.g., acetic acid bacteria (Acetobacter)), and microbial products. Any of these can be used.
• Cellulose raw materials derived from plants or microorganisms are preferred, and cellulose raw materials derived from plants are more preferred.
• the phosphate group-containing nanocellulose (C1) From the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster and does not cause wrinkles at edge portions, which tend to be thicker than general portions, and does not cause sagging at vertical portions, the phosphate group-containing nanocellulose (C1) preferably contains phosphate group-containing cellulose nanofibers (C11) and/or phosphate group-containing cellulose nanocrystals (C12), and more preferably contains phosphate group-containing cellulose nanofibers (C11).
• the phosphate group-containing cellulose nanofiber (C11) has excellent metallic or pearlescent metallic or pearlescent luster, and from the viewpoint of forming a coating film that does not wrinkle at the edge portions, which tend to be thicker than the general portions, and does not sag at the vertical portions, the number average fiber diameter is preferably within the range of 2 to 500 nm, more preferably 2 to 250 nm, and even more preferably 2 to 150 nm.
• the number average fiber length is preferably within the range of 0.1 to 20 ⁇ m, more preferably 0.1 to 15 ⁇ m, and even more preferably 0.1 to 10 ⁇ m.
• the aspect ratio which is the value obtained by dividing the number average fiber length by the number average fiber diameter, is preferably within the range of 50 to 10,000, more preferably 50 to 5,000, and even more preferably 50 to 1,000.
• the number-average fiber diameter and number-average fiber length are measured and calculated from images obtained by, for example, dispersing a sample of phosphate-containing cellulose nanofiber (C11) diluted with water and casting it onto a hydrophilically treated carbon film-coated grid observed under a transmission electron microscope (TEM).
• TEM transmission electron microscope
• the manufacturing method of the phosphate group-containing cellulose nanofiber (C11) is not particularly limited, but may include, for example, a step of introducing phosphate groups into the cellulose raw material and a defibration process.
• the phosphate group introduction process is a process of reacting a compound having a phosphate group and/or its salt with the cellulose raw material in the presence of urea and/or its derivative. This introduces phosphate groups into the hydroxyl groups of the cellulose raw material.
• the defibration process is a process of micronizing the fiber raw material into which the phosphate group has been introduced (hereinafter referred to as "phosphate group-introduced cellulose fiber") to the nano level.
• the above processing steps are performed in the order of the phosphate group introduction process and the defibration process.
• the phosphate group introduction process includes a step of introducing phosphate groups into cellulose, and may also include, as desired, an alkali treatment process, a process of washing off excess reagents, a heat treatment process of cleaving condensed phosphate groups, and the like.
• the compound having a phosphate group and/or its salt is a compound that contains a phosphorus atom and can form an ester bond with cellulose.
• the compound that contains a phosphorus atom and can form an ester bond with a hydroxyl group of cellulose is, for example, at least one selected from phosphoric acid, a salt of phosphoric acid, a dehydration condensation product of phosphoric acid, a salt of a dehydration condensation product of phosphoric acid, diphosphorus pentoxide, and phosphorus oxychloride, or a mixture of these, but is not limited thereto. All of them may contain water in the form of hydrate water or the like, or may be an anhydride that does not substantially contain water.
• salts of phosphates and dehydrated condensates of phosphoric acid lithium salts, sodium salts, potassium salts, ammonium salts, organic ammonium salts, organic phosphonium salts of phosphoric acid and dehydrated condensates of phosphoric acid, as well as salts with any compound exhibiting basicity can be selected, but are not particularly limited.
• phosphoric acid sodium salts of phosphoric acid, potassium salts of phosphoric acid, and ammonium salts of phosphoric acid are preferred from the viewpoints of high efficiency of introduction of phosphate groups, easier improvement of defibration efficiency in the defibration step described below, low cost, and ease of industrial application.
• Phosphoric acid, ammonium dihydrogen phosphate, and sodium dihydrogen phosphate are more preferred.
• urea and/or its derivatives include, but are not limited to, urea, thiourea, biuret, phenylurea, benzylurea, dimethylurea, diethylurea, tetramethylurea, benzoleinurea, hydantoin, etc.
• urea is preferred because it is low cost, easy to handle, and easily forms hydrogen bonds with fiber raw materials having hydroxyl groups.
• the reaction system may contain amides or amines.
• amides include formamide, dimethylformamide, acetamide, and dimethylacetamide.
• amines include methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine, and hexamethylenediamine.
• triethylamine in particular is known to act as a good reaction catalyst.
• the amount of phosphate groups introduced into the cellulose raw material is not particularly limited, but is preferably 0.10 to 3.65 mmol/g per gram (mass) of fine cellulose fiber, more preferably 0.20 to 3.00 mmol/g, and even more preferably 0.50 to 2.00 mmol/g.
• the content of the phosphate group-containing nanocellulose (C1) in the photoluminescent pigment dispersion of the present invention is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 7.5 parts by mass, and even more preferably 0.3 to 5 parts by mass, based on 100 parts by mass of solids in the photoluminescent pigment dispersion, from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster, does not develop wrinkles at edges where the film thickness tends to be thicker than in general parts, and does not develop sagging at vertical parts.
• Carboxyl group-containing nanocellulose (C2) The carboxyl group-containing nanocellulose (C2) preferably contains carboxyl group-containing cellulose nanofiber (C21) and/or carboxyl group-containing cellulose nanocrystal (C22), and more preferably contains carboxyl group-containing cellulose nanofiber (C21), from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster and does not cause wrinkles at edge portions where the film thickness tends to be thicker than in general portions, and does not cause sagging at vertical portions.
• the amount of carboxyl groups in the carboxyl group-containing cellulose nanofiber (C21) is preferably 0.80 to 1.10 mmol/g, more preferably 0.85 to 1.10 mmol/g, and even more preferably 0.90 to 1.10 mmol/g, relative to the bone dry mass of the cellulose nanofiber.
• Carboxyl group-containing cellulose nanofibers (C21) can be obtained by defibrating oxidized cellulose obtained by introducing carboxyl groups into a cellulose raw material using a known method.
• One method for introducing carboxyl groups into a cellulose raw material is, for example, to oxidize the cellulose raw material in water using an oxidizing agent in the presence of an N-oxyl compound and a bromide, iodide, or a mixture of these. This oxidation reaction selectively oxidizes the primary hydroxyl group at the C6 position of the pyranose ring on the cellulose surface.
• a carboxyl group (-COOH) or a carboxylate group (-COO-) can be introduced onto the surface.
• N-oxyl compound is a compound that can generate nitroxy radicals. Any compound that promotes the desired oxidation reaction can be used as an N-oxyl compound. Examples include 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO) and its derivatives (e.g., 4-hydroxyTEMPO).
• TEMPO 2,2,6,6-tetramethylpiperidine-1-oxy radical
• 4-hydroxyTEMPO 4-hydroxyTEMPO
• the amount of N-oxyl compound is not particularly limited, as long as it is a catalytic amount capable of oxidizing the raw material cellulose.
• the concentration of the N-oxyl compound in the reaction system is preferably about 0.1 mmol/L to 4 mmol/L.
• Bromides are compounds that contain bromine, including alkali metal bromides that can dissociate and ionize in water.
• Iodides are compounds that contain iodine, including alkali metal iodides.
• the amount of bromide or iodide can be selected within a range that can promote the oxidation reaction.
• the total amount of bromide and iodide is preferably 0.1 mmol to 100 mmol, more preferably 0.1 mmol to 10 mmol, and even more preferably 0.5 mmol to 5 mmol, per 1 g of bone-dry cellulose.
• the oxidizing agent may be any known oxidizing agent, such as halogens, hypohalous acids, hypohalous acids, perhalogen acids or their salts, halogen oxides, peroxides, etc.
• halogens such as halogens, hypohalous acids, hypohalous acids, perhalogen acids or their salts, halogen oxides, peroxides, etc.
• sodium hypochlorite is preferred because it is inexpensive and has a low environmental impact.
• the amount of oxidizing agent is preferably 0.5 mmol to 500 mmol, more preferably 0.5 mmol to 50 mmol, and even more preferably 1 mmol to 25 mmol, per 1 g of bone-dry cellulose. Also, for example, the amount of oxidizing agent is preferably 1 mol to 40 mol per 1 mol of N-oxyl compound.
• the cellulose oxidation process can proceed efficiently even under relatively mild conditions.
• the reaction temperature is preferably 4°C to 40°C, and may be room temperature of about 15°C to 30°C.
• carboxyl groups are generated in the cellulose, and the pH of the reaction solution decreases.
• an alkaline solution such as an aqueous sodium hydroxide solution during the reaction to maintain the pH of the reaction solution at 8 to 12, preferably 9 to 12, and more preferably about 10 to 12. Water is preferred as the reaction medium because it is easy to handle and is less likely to cause side reactions.
• the reaction time for the oxidation reaction can be set appropriately according to the degree of oxidation progress, and is usually 0.5 to 6 hours.
• the oxidation reaction may also be carried out in two stages.
• the carboxylated cellulose obtained by filtering after the first stage reaction is oxidized again under the same or different reaction conditions, allowing efficient oxidation without reaction inhibition by salt produced as a by-product in the first stage reaction.
• Another example is a method of oxidation by contacting cellulose raw materials with a gas containing ozone. This oxidation reaction oxidizes at least the hydroxyl groups at positions 2 and 6 of the pyranose ring, and causes the cellulose chain to break down.
• the ozone concentration in the ozone-containing gas is preferably 50 g/m 3 to 250 g/m 3 , and more preferably 50 g/m 3 to 220 g/m 3.
• the amount of ozone added to the cellulose raw material is preferably 0.1 parts by mass to 30 parts by mass, and more preferably 5 parts by mass to 30 parts by mass, based on 100 parts by mass of the solid content of the cellulose raw material.
• the ozone treatment temperature is preferably 0°C to 50°C, and more preferably 20°C to 50°C.
• the ozone treatment time is not particularly limited, but is about 1 minute to 360 minutes, and preferably about 30 minutes to 360 minutes.
• a further oxidation treatment may be carried out using an oxidizing agent.
• the oxidizing agent used in the further oxidation treatment is not particularly limited, but examples include chlorine compounds such as chlorine dioxide and sodium chlorite, oxygen, hydrogen peroxide, persulfuric acid, and peracetic acid.
• these oxidizing agents can be dissolved in a polar organic solvent such as water or alcohol to prepare an oxidizing agent solution, and the further oxidation treatment can be carried out by immersing the cellulose raw material in the solution.
• the amount of carboxyl groups which indicates the degree of modification of oxidized cellulose, can be adjusted by controlling the reaction conditions, such as the amount of oxidizing agent added and the reaction time, as described above.
• the amount of carboxyl groups is preferably 0.80 to 1.10 mmol/g, more preferably 0.85 to 1.10 mmol/g, and even more preferably 0.90 to 1.10 mmol/g, relative to the bone dry mass of oxidized cellulose.
• the amount of carboxyl groups refers to the total amount of carboxyl groups (-COOH) and carboxylate groups (-COO-).
• Carboxyl group amount [mmol/g pulp] a [ml] x 0.05/mass of oxidized pulp [g].
• the degree of modification of oxidized cellulose can be regarded as the degree of modification of the defibrated cellulose nanofibers.
• the device used for defibration is not particularly limited, but examples include devices of high-speed rotation type, colloid mill type, high-pressure type, roll mill type, ultrasonic type, etc., and a high-pressure or ultra-high-pressure homogenizer is preferable, and a wet high-pressure or ultra-high-pressure homogenizer is more preferable.
• the device is preferably capable of applying a strong shear force to the cellulose raw material or oxidized cellulose (usually a dispersion liquid).
• the pressure that the device can apply is preferably 50 MPa or more, more preferably 100 MPa or more, and even more preferably 140 MPa or more.
• the device is preferably a wet high-pressure or ultra-high-pressure homogenizer that can apply the above pressure to the cellulose raw material or oxidized cellulose (usually a dispersion liquid) and can apply a strong shear force. This allows defibration to be performed efficiently.
• the number of treatments (passes) in the defibration device may be one or two or more, and two or more are preferable.
• oxidized cellulose is usually dispersed in a solvent.
• a solvent there are no particular limitations on the solvent as long as it can disperse oxidized cellulose, but examples include water, organic solvents (e.g., hydrophilic organic solvents such as methanol), and mixtures of these. Since the cellulose raw material is hydrophilic, it is preferable that the solvent is water.
• the solids concentration of oxidized cellulose in the dispersion is usually 0.1% by mass or more, preferably 0.2% by mass or more, and more preferably 0.3% by mass or more. This ensures that the amount of liquid relative to the amount of cellulose fiber raw material is appropriate and efficient.
• the upper limit is usually 10% by mass or less, and preferably 6% by mass or less. This allows fluidity to be maintained.
• the order of the defibration process and the dispersion process is not particularly limited, and either may be performed first, or they may be performed simultaneously, but it is preferable to perform the defibration process after the dispersion process.
• Each combination of processes needs to be performed at least once, and may be repeated two or more times.
• preliminary treatment may be carried out prior to the defibration or dispersion treatment.
• the preliminary treatment may be carried out using a mixing, stirring, emulsifying, or dispersing device such as a high-speed shear mixer.
• the average fiber diameter of the carboxyl group-containing cellulose nanofiber (C21) is preferably 3 nm or more or 500 nm or less, more preferably 3 nm or more or 50 nm or less, and even more preferably 3 nm or more or 20 nm or less.
• the average fiber length is preferably 60 nm or more or less than 2500 nm, more preferably 75 nm or more or less than 2250 nm, and even more preferably 90 nm or more or less than 900 nm.
• the average fiber diameter and average fiber length of the carboxyl group-containing cellulose nanofiber (C21) can be measured, for example, by preparing a 0.001 mass% aqueous dispersion of the carboxyl group-containing cellulose nanofiber (C21), spreading this diluted dispersion thinly on a mica sample stage, and drying it by heating at 50°C to prepare a sample for observation, and measuring the cross-sectional height of the shape image observed with an atomic force microscope (AFM), thereby calculating the number average fiber diameter or number average fiber length.
• AFM atomic force microscope
• the average aspect ratio of the carboxyl group-containing cellulose nanofiber (C21) is preferably 20 or more and less than 50, more preferably in the range of 25 to 45, and even more preferably in the range of 30 to 45.
• the content of the carboxyl group-containing nanocellulose (C2) in the photoluminescent pigment dispersion of the present invention is preferably 1 to 30 parts by mass, more preferably 2 to 25 parts by mass, and even more preferably 3 to 20 parts by mass, based on 100 parts by mass of solids in the photoluminescent pigment dispersion, from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster, does not develop wrinkles at edges where the film thickness tends to be thicker than in general parts, and does not develop sagging at vertical parts.
• the content ratio of the phosphate group-containing nanocellulose (C1) and the carboxyl group-containing nanocellulose (C2) in the brilliant pigment dispersion of the present invention is preferably within the range of 1/99 to 50/50, more preferably within the range of 3/97 to 45/55, and even more preferably within the range of 5/95 to 40/60, in terms of the mass ratio ((C1)/(C2)) of the phosphate group-containing nanocellulose (C1) to the carboxyl group-containing nanocellulose (C2), from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster, does not develop wrinkles at the edge portions where the film thickness tends to be thicker than in the general portions, and does not develop sagging at the vertical portions.
• the sulfonic acid group-containing nanocellulose (C3) preferably contains sulfonic acid group-containing cellulose nanofiber (C31) and/or sulfonic acid group-containing cellulose nanocrystal (C32), and more preferably contains sulfonic acid group-containing cellulose nanocrystal (C32), from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster and does not cause wrinkles at edge portions where the film thickness tends to be thicker than in general portions, and does not cause sagging at vertical portions.
• Sulfonic acid group-containing cellulose nanocrystals can be produced by known methods. Specifically, for example, they can be obtained by a chemical treatment process in which a fiber raw material containing cellulose is chemically treated to introduce sulfo groups, and a process in which the amorphous portion is hydrolyzed with concentrated sulfuric acid or the like.
• the number average fiber diameter of the sulfonic acid group-containing cellulose nanocrystal (C32) is preferably within the range of 1 to 50 nm, more preferably within the range of 1 to 30 nm, particularly preferably within the range of 1 to 15 nm, and even more particularly preferably within the range of 1 to 5 nm, from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster, does not develop wrinkles at the edge portions, which tend to be thicker than the general portions, and does not develop sagging at the vertical portions.
• the number average fiber length of the sulfonic acid group-containing cellulose nanocrystal (C32) is preferably within the range of 10 to 500 nm, more preferably within the range of 10 to 300 nm, particularly preferably within the range of 20 to 250 nm, and even more particularly preferably within the range of 30 to 150 nm, from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster, does not develop wrinkles at the edge portions, which tend to be thicker than the general portions, and does not develop sagging at the vertical portions.
• the number-average fiber diameter and number-average fiber length are measured and calculated from images obtained by, for example, dispersing a sample of sulfonic acid group-containing cellulose nanocrystals (C32) diluted with water and casting it onto a carbon film-coated grid that has been hydrophilized, and observing the result with a transmission electron microscope (TEM).
• C32 sulfonic acid group-containing cellulose nanocrystals
• the content of sulfonic acid group-containing nanocellulose (C3) in the photoluminescent pigment dispersion of the present invention is preferably 1 to 30 parts by mass, more preferably 2 to 25 parts by mass, and even more preferably 3 to 20 parts by mass, based on 100 parts by mass of solids in the photoluminescent pigment dispersion, from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster, does not develop wrinkles at edges where the film thickness tends to be thicker than in general parts, and does not develop sagging at vertical parts.
• the content ratio of the phosphate group-containing nanocellulose (C1) and the sulfonic acid group-containing nanocellulose (C3) in the brilliant pigment dispersion of the present invention is preferably within the range of 1/99 to 50/50, more preferably within the range of 3/97 to 45/55, and even more preferably within the range of 5/95 to 40/60, in terms of the mass ratio ((C1)/(C3)) of the phosphate group-containing nanocellulose (C1) to the sulfonic acid group-containing nanocellulose (C3), from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster, does not develop wrinkles at the edge portions where the film thickness tends to be thicker than in the general portions, and does not develop sagging at the vertical portions.
• the content ratio of the phosphate group-containing nanocellulose (C1) to at least one selected from the group consisting of carboxyl group-containing nanocellulose (C2) and sulfonic acid group-containing nanocellulose (C3) in the brilliant pigment dispersion of the present invention is preferably within the range of 1/99 to 50/50, more preferably within the range of 3/97 to 45/55, and even more preferably within the range of 5/95 to 40/60, in terms of the mass ratio ((C1)/[(C2) and (C3)]) of the phosphate group-containing nanocellulose (C1) to at least one selected from the group consisting of carboxyl group-containing nanocellulose (C2) and sulfonic acid group-containing nanocellulose (C3), from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster, does not develop wrinkles at edge portions where the film thickness tends to be thicker than in general portions, and does not develop sagging at vertical portions.
• the content of nanocellulose (C) in the photoluminescent pigment dispersion of the present invention is preferably 1 to 30 parts by mass, more preferably 2 to 25 parts by mass, and even more preferably 3 to 20 parts by mass, based on 100 parts by mass of solids in the photoluminescent pigment dispersion, from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster, does not develop wrinkles at edges where the film thickness tends to be thicker than in general parts, and does not develop sagging at vertical parts.
• the glittering pigment dispersion of the present invention is a glittering pigment dispersion containing a wetting agent (A), a glittering pigment (B), nanocellulose (C) and water (D),
• the solid content is 0.1 to 10 parts by mass relative to 100 parts by mass of the total of all components of the brilliant pigment dispersion
• the nanocellulose (C) is a glittering pigment dispersion containing at least one selected from the group consisting of phosphate group-containing nanocellulose (C1), carboxyl group-containing nanocellulose (C2), and sulfonic acid group-containing nanocellulose (C3).
• the content of water (D) in the photoluminescent pigment dispersion of the present invention is preferably within the range of 50 to 95 parts by mass, more preferably within the range of 60 to 90 parts by mass, and even more preferably within the range of 70 to 90 parts by mass, per 100 parts by mass of all components of the photoluminescent pigment dispersion, from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster, does not develop wrinkles at the edge parts where the film thickness tends to be thicker than in the general parts, and does not develop sagging at vertical parts.
• the solid content is preferably within the range of 0.5 to 8 parts by mass, and more preferably within the range of 1.5 to 6 parts by mass, per 100 parts by mass of all the components of the glitter pigment dispersion.
• the photoluminescent pigment dispersion of the present invention may also contain a resin water dispersion from the viewpoint of water resistance of the resulting coating film.
• the resin water dispersion is a dispersion in which a resin is dispersed in an aqueous solvent, and may contain at least one selected from the group consisting of a urethane resin water dispersion, an acrylic resin water dispersion, a polyester resin water dispersion, an olefin resin water dispersion, and a composite of these resins.
• the water dispersion may be modified.
• urethane resin aqueous dispersions and acrylic resin aqueous dispersions are preferred, with hydroxyl group-containing urethane resin aqueous dispersions and hydroxyl group-containing acrylic resin aqueous dispersions being more preferred, and hydroxyl group-containing acrylic resin aqueous dispersions being particularly preferred.
• the hydroxyl-containing acrylic resin aqueous dispersion is preferably of the core-shell type.
• the content is preferably within the range of 1 to 60 parts by mass, and more preferably within the range of 5 to 40 parts by mass, based on 100 parts by mass of the solid content in the photoluminescent pigment dispersion.
• the glittering pigment dispersion may further contain, as necessary, an organic solvent, a pigment other than the glittering pigment (B), a viscosity adjuster other than the nanocellulose (C), a binder resin other than the resin water dispersion, a crosslinkable component, a pigment dispersant, an anti-settling agent, an ultraviolet absorber, a light stabilizer, and the like.
• Pigments other than the above-mentioned luster pigment (B) include color pigments, extender pigments, etc.
• color pigments examples include titanium oxide, zinc oxide, carbon black, molybdenum red, Prussian blue, cobalt blue, azo pigments, phthalocyanine pigments, quinacridone pigments, isoindoline pigments, threne pigments, perylene pigments, dioxazine pigments, diketopyrrolopyrrole pigments, etc., and among these, carbon black is preferably used.
• the content is preferably within the range of 0.1 to 10 parts by mass, and more preferably within the range of 0.5 to 5 parts by mass, based on 100 parts by mass of the solid content in the photoluminescent pigment dispersion.
• extender pigment examples include clay, kaolin, barium sulfate, barium carbonate, calcium carbonate, talc, silica, and alumina white.
• the content is preferably within the range of 0.1 to 10 parts by mass, and more preferably within the range of 0.5 to 5 parts by mass, based on 100 parts by mass of the solid content in the photoluminescent pigment dispersion.
• polyacrylic acid-based viscosity modifiers that can be used besides the nanocellulose (C) include polyacrylic acid-based viscosity modifiers, polyamide-based viscosity modifiers, mineral-based viscosity modifiers, cellulose-based viscosity modifiers (excluding nanocellulose), polysaccharide-based viscosity modifiers, etc., and among these, it is preferable to use polyacrylic acid-based viscosity modifiers from the viewpoint of forming a coating film that does not wrinkle at the edge parts, which tend to be thicker than the general parts, and does not sag at the vertical parts.
• polyacrylic acid-based viscosity modifiers examples include sodium polyacrylate, polyacrylic acid-(meth)acrylic acid ester copolymers, etc.
• polyacrylic acid viscosity modifiers include, for example, “Primal ASE-60”, “Primal TT615", and “Primal RM5" (all trade names) manufactured by Dow Chemical Company, and "SN Thickener 613", “SN Thickener 618”, “SN Thickener 630”, “SN Thickener 634", and “SN Thickener 636” (all trade names) manufactured by San Nopco Ltd.
• the solid content acid value of the polyacrylic acid viscosity modifier is preferably within the range of 30 to 300 mg KOH/g, and more preferably 80 to 280 mg KOH/g.
• Polyamide-based viscosity modifiers include polyamide amine salts and fatty acid polyamides.
• mineral-based viscosity modifiers include swellable layered silicates whose crystal structure is a 2:1 type structure.
• Specific examples include smectite clay minerals such as natural or synthetic montmorillonite, saponite, hectorite, stevensite, beidellite, nontronite, bentonite, and laponite, as well as swellable mica clay minerals such as Na-type tetrasilicic fluorine mica, Li-type tetrasilicic fluorine mica, Na-salt type fluorine taeniolite, and Li-type fluorine taeniolite, as well as vermiculite, or substitutes or derivatives thereof, or mixtures thereof.
• Cellulose-based viscosity modifiers include carboxymethylcellulose, methylcellulose, hydroxyethylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, etc.
• Polysaccharide viscosity regulators include guar gum, xanthan gum, and locust bean gum.
• the photoluminescent pigment dispersion of the present invention contains a viscosity modifier other than nanocellulose (C)
• the content is preferably within the range of 1 to 30 parts by mass, and more preferably within the range of 3 to 20 parts by mass, based on 100 parts by mass of the solid content in the photoluminescent pigment dispersion.
• the crosslinkable component is a component for crosslinking and curing the glitter pigment dispersion by heating when the dispersion contains the resin water dispersion.
• the crosslinkable component may be a component for self-crosslinking, or a component for crosslinking and curing with a part of the colored paint forming the colored coating film described below or a part of the clear paint forming the clear coating film described below.
• crosslinkable component examples include amino resins, urea resins, polyisocyanate compounds, blocked polyisocyanate compounds, epoxy group-containing compounds, carboxyl group-containing compounds, carbodiimide group-containing compounds, hydrazide group-containing compounds, semicarbazide group-containing compounds, and silane coupling agents.
• amino resins, polyisocyanate compounds, and blocked polyisocyanate compounds that can react with hydroxyl groups, and carbodiimide group-containing compounds that can react with carboxyl groups are preferred.
• the polyisocyanate compounds and blocked polyisocyanate compounds those described in the section on clear coatings described below can be used.
• the above crosslinkable components can be used alone or in combination of two or more.
• the content thereof is preferably within the range of 0.5 to 100 parts by mass, more preferably within the range of 1 to 95 parts by mass, and even more preferably within the range of 2 to 90 parts by mass, in terms of the water resistance of the resulting coating film, based on 100 parts by mass of the photoluminescent pigment (B) in the photoluminescent pigment dispersion of the present invention.
• the total content of the binder resin and crosslinkable component is, from the viewpoint of the metallic or pearlescent luster and water-resistant adhesion of the resulting coating film, preferably within the range of 1 to 200 parts by mass in terms of solid content, more preferably within the range of 2 to 150 parts by mass, and even more preferably within the range of 3 to 100 parts by mass, based on 100 parts by mass of the solid content of the photoluminescent pigment (B) in the photoluminescent pigment dispersion.
• the glittering pigment dispersion of the present invention has an excellent metallic or pearlescent metallic or pearlescent luster, and from the viewpoint of forming a coating film that does not develop wrinkles at edge portions which tend to be thicker than general portions, and does not develop sagging at vertical portions, the viscosity at a rotation speed of 6 revolutions per minute (6 rpm) is preferably within the range of 400 to 10,000 mPa sec, more preferably within the range of 500 to 8,000 mPa sec, and even more preferably within the range of 600 to 6,000 mPa sec.
• the viscosity is defined as the viscosity one minute after the start of measurement under certain conditions. Specifically, the prepared photoluminescent pigment dispersion is placed in a specified container and a rotary mixer is used to set the rotation speed to 1000 rpm and mix until homogenous. Measurement is then started at a temperature of 20°C and 6 rpm using a B-type viscometer, and the viscosity is defined as the viscosity one minute after the start (also referred to as the "B6 value" in this specification).
• the viscometer used here is the "LVDV-I" (product name, B-type viscometer, manufactured by BROOKFIELD).
• a rotation speed of 6 rpm is a common condition for controlling the viscosity of pseudoplastic liquids.
• the method for forming a multi-layer coating film of the present invention comprises the steps of: Step (1): A step of applying a base coating material (X) onto a substrate to form an uncured base coating film; Step (2): A step of applying the glittering pigment dispersion of the present invention onto the base coating film formed in step (1) to form an uncured glittering coating film; Step (3): A step of applying an uncured clear coating (Z) onto the glossy coating film formed in step (2) to form a clear coating film; and Step (4): A method for forming a multilayer coating film, comprising a step of simultaneously heating and curing the uncured base coating film formed in step (1), the uncured glossy coating film formed in step (2), and the uncured clear coating film formed in step (3).
• Substrate The multilayer coating film of the present invention is formed on the substrate shown below.
• substrates include metals such as iron, zinc, and aluminum, alloys containing these metals, and molded products made from these metals, as well as molded products and films made from glass, plastic, foam, and the like. These materials can be degreased or surface-treated as appropriate to create substrates. Examples of such surface treatments include phosphate treatment, chromate treatment, and complex oxide treatment. Furthermore, if the substrate is made of metal, it is preferable that a primer coating film is formed on the surface-treated metal material using a cationic electrocoating paint or the like. Furthermore, if the substrate is made of plastic, it is preferable that a primer coating film is formed on the degreased plastic material using a primer paint.
• Base paint (X) As the base coating material (X), specifically, a known thermosetting coating material containing as main components a base resin, a crosslinking agent, a pigment, and a solvent such as an organic solvent and/or water can be used.
• the base resin used in the base coating (X) may be a thermosetting resin or a room temperature curing resin, but from the standpoint of water resistance, chemical resistance, weather resistance, etc., a thermosetting resin is preferable.
• the base resin a resin with good weather resistance and transparency is suitable, and specific examples include acrylic resin, polyester resin, epoxy resin, urethane resin, etc.
• acrylic resin examples include ⁇ , ⁇ -ethylenically unsaturated carboxylic acids, (meth)acrylic acid esters having functional groups such as hydroxyl groups, amide groups, methylol groups, and epoxy groups, and resins obtained by copolymerizing other (meth)acrylic acid esters, styrene, etc.
• polyester resins include polyester resins obtained by the condensation reaction of polyhydric alcohols such as ethylene glycol, propylene glycol, butylene glycol, 1,6-hexanediol, trimethylolpropane, and pentaerythritol with polycarboxylic acid components such as adipic acid, isophthalic acid, terephthalic acid, phthalic anhydride, hexahydrophthalic anhydride, and trimellitic anhydride.
• polyhydric alcohols such as ethylene glycol, propylene glycol, butylene glycol, 1,6-hexanediol, trimethylolpropane, and pentaerythritol
• polycarboxylic acid components such as adipic acid, isophthalic acid, terephthalic acid, phthalic anhydride, hexahydrophthalic anhydride, and trimellitic anhydride.
• An example of an epoxy resin is the so-called bisphenol A type epoxy resin, which is produced by the condensation reaction of bisphenol A and epichlorohydrin.
• urethane resins include compounds obtained by the addition reaction of diisocyanate compounds with polyhydric alcohols, and those obtained by reacting the above-mentioned acrylic resins, polyester resins, or epoxy resins with diisocyanate compounds to increase the molecular weight.
• the base paint (X) may be either a water-based paint or a solvent-based paint, but from the viewpoint of reducing the VOC of the paint, it is preferable that the base paint is a water-based paint.
• the base resin is a resin containing a sufficient amount of hydrophilic groups, such as carboxyl groups, hydroxyl groups, methylol groups, amino groups, sulfonic acid groups, polyoxyethylene bonds, etc., most commonly carboxyl groups, to make the resin water-soluble or water-dispersible, and the hydrophilic groups are neutralized to form alkaline salts to make the base resin water-soluble or water-dispersible.
• the amount of hydrophilic groups is not particularly limited and can be selected as desired depending on the degree of water-solubilization or water-dispersion, but generally, it can be about 10 mg KOH/g or more, preferably within the range of 30 to 200 mg KOH/g, based on the acid value.
• alkaline substances used for neutralization include sodium hydroxide and amine compounds.
• the resin can also be dispersed in water by emulsion polymerization of the polymerizable component in the presence of a surfactant or a water-soluble resin. Furthermore, the resin can also be dispersed in water in the presence of an emulsifier, for example.
• the base resin may not contain any hydrophilic groups at all, or may contain less of them than the water-soluble resin.
• the crosslinking agent is used to crosslink and harden the base resin by heating, and can be any of the crosslinking components exemplified in the description of the brilliant pigment dispersion of the present invention.
• the ratio of each of the above components in the base coating (X) can be selected as desired, but from the viewpoints of water resistance, finish, etc., it is generally preferable that the base resin and crosslinking agent are within the ranges of 60 to 90 mass%, particularly 70 to 85 mass%, of the former and 10 to 40 mass%, particularly 15 to 30 mass%, of the latter, based on the total mass of the two components.
• the pigment provides the base coating film formed by the base paint (X) with brilliance, color, and base hiding properties.
• the type and amount of the pigment can be adjusted appropriately depending on the hue or brightness desired for the multi-layer coating film.
• pigments examples include luster pigments, color pigments, and extender pigments.
• the cured film thickness of the base coating film obtained from the base paint (X) is preferably within the range of 3 ⁇ m to 50 ⁇ m, more preferably within the range of 5 to 45 ⁇ m, and even more preferably within the range of 7 to 40 ⁇ m, from the viewpoints of the hiding power of the base and the metallic or pearlescent luster of the multi-layer coating film.
• the base paint (X) can be applied according to a normal method.
• the base paint (X) is a water-based paint, for example, deionized water and, if necessary, additives such as a thickener and an antifoaming agent can be added to the base paint (X) to adjust the solid content to about 10-70% by mass and the viscosity to 500-6000 cps/6 rpm (B-type viscometer), and then the surface of the substrate can be sprayed or sprayed with a rotary atomizer.
• the solid content within the range of 10-20% by mass.
• electrostatic application can also be performed if necessary.
• the base paint (X) preferably has a black-and-white hiding film thickness of 80 ⁇ m or less, more preferably 10 to 60 ⁇ m, and even more preferably 15 to 50 ⁇ m.
• the "black-and-white hiding film thickness” is the minimum film thickness at which the boundary between the black and white checkered pattern of the hiding rate test paper, as specified in JIS K5600-4-1, 4.1.2, is no longer visible when a black-and-white checkered pattern hiding rate test paper is attached to a steel plate, the paint is applied at an angle so that the film thickness changes continuously, and the paint is dried or cured. The paint surface is then visually observed under diffuse daylight, and the minimum film thickness at which the boundary between the black and white checkered pattern of the hiding rate test paper is no longer visible is measured with an electromagnetic film thickness gauge.
• the coating When applying the photoluminescent pigment dispersion of the present invention onto an uncured base coating film of base paint (X), after applying the base paint (X), the coating can be left at room temperature for 15 to 30 minutes, or heated at a temperature of 50 to 100°C for 30 seconds to 10 minutes, and then the photoluminescent pigment dispersion of the present invention can be applied.
• the glittering pigment dispersion (Y) of the present invention can be coated by electrostatic coating, air spray, airless spray, etc. These coating methods may be electrostatically applied as necessary. In the method for forming a multi-layer coating film of the present invention, rotary atomization type electrostatic coating is particularly preferred.
• the dry thickness of the glitter coating is preferably 0.025 to 3 ⁇ m, and more preferably 0.15 to 2.5 ⁇ m.
• the clear coating (Z) can be applied after leaving it at room temperature for 15 to 30 minutes or heating it at a temperature of 50 to 100°C for 30 seconds to 10 minutes.
• the clear coating material (Z) may be any known thermosetting clear coating material composition.
• the thermosetting clear coating material composition include organic solvent-based thermosetting coating materials containing a base resin having a crosslinkable functional group and a curing agent, water-based thermosetting coating materials, and powder thermosetting coating materials.
• Examples of the crosslinkable functional groups possessed by the base resin include carboxyl groups, hydroxyl groups, epoxy groups, and silanol groups.
• Examples of the types of base resin include acrylic resins, polyester resins, alkyd resins, urethane resins, epoxy resins, and fluororesins.
• Examples of the curing agent include polyisocyanate compounds, blocked polyisocyanate compounds, melamine resins, urea resins, carboxyl group-containing compounds, carboxyl group-containing resins, epoxy group-containing resins, and epoxy group-containing compounds.
• Preferred combinations of base resin/curing agent for the clear coating (Z) include carboxyl group-containing resin/epoxy group-containing resin, hydroxyl group-containing resin/polyisocyanate compound, hydroxyl group-containing resin/blocked polyisocyanate compound, hydroxyl group-containing resin/melamine resin, etc.
• the clear coating material (Z) may be a one-component coating material or a multi-component coating material such as a two-component coating material.
• the clear coating (Z) is preferably a two-component clear coating containing the following hydroxyl group-containing resin and polyisocyanate compound, from the viewpoint of the adhesion of the resulting coating film.
• Hydroxyl- containing resin any conventionally known resin can be used without any restrictions as long as it contains hydroxyl groups.
• the hydroxyl-containing resin include hydroxyl-containing acrylic resin, hydroxyl-containing polyester resin, hydroxyl-containing polyether resin, and hydroxyl-containing polyurethane resin, and preferred examples include hydroxyl-containing acrylic resin and hydroxyl-containing polyester resin, and particularly preferred examples include hydroxyl-containing acrylic resin.
• the hydroxyl value of the hydroxyl-containing acrylic resin is preferably within the range of 80 to 200 mgKOH/g, and more preferably within the range of 100 to 180 mgKOH/g, from the viewpoint of the scratch resistance and water resistance of the coating film.
• the weight average molecular weight of the hydroxyl-containing acrylic resin is preferably within the range of 2,500 to 40,000, and more preferably within the range of 5,000 to 30,000, from the viewpoint of the acid resistance and smoothness of the coating film.
• the weight average molecular weight is a value calculated based on the molecular weight of standard polystyrene from a chromatogram measured by gel permeation chromatography.
• the gel permeation chromatograph used was "HLC8120GPC” (manufactured by Tosoh Corporation). Four columns were used: “TSKgel G-4000HXL”, “TSKgel G-3000HXL”, “TSKgel G-2500HXL”, and "TSKgel G-2000HXL” (all product names manufactured by Tosoh Corporation). The conditions were as follows: mobile phase: tetrahydrofuran, measurement temperature: 40°C, flow rate: 1 cc/min, detector: RI.
• the glass transition temperature of the hydroxyl-containing acrylic resin is preferably -40°C to 20°C, and more preferably within the range of -30°C to 10°C. If the glass transition temperature is -40°C or higher, the coating film will have sufficient hardness, and if it is 20°C or lower, the coating film will be able to maintain its surface smoothness.
• the polyisocyanate compound is a compound having at least two isocyanate groups in one molecule, and examples thereof include aliphatic polyisocyanates, alicyclic polyisocyanates, araliphatic polyisocyanates, aromatic polyisocyanates, and derivatives of the polyisocyanates.
• aliphatic polyisocyanates examples include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, dimer acid diisocyanate, methyl 2,6-diisocyanatohexanoate (common name: lysine diisocyanate), isocyanate); aliphatic triisocyanates such as 2-isocyanatoethyl 2,6-diisocyanatohexanoate, 1,6-diisocyanato-3-isocyanatomethylhexane, 1,4,8-triisocyanatooctane, 1,6,11-triisocyanatounde
• alicyclic polyisocyanate examples include 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (common name: isophorone diisocyanate), 4-methyl-1,3-cyclohexylene diisocyanate (common name: hydrogenated TDI), 2-methyl-1,3-cyclohexylene diisocyanate, cycloaliphatic diisocyanates such as 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane (common name: hydrogenated xylylene diisocyanate) or mixtures thereof, methylenebis(4,1-cyclohexanediyl)diisocyanate (common name: hydrogenated MDI), and norbornane diisocyanate; 1,3,5-triisocyanatol
• aromatic aliphatic polyisocyanate examples include aromatic aliphatic diisocyanates such as methylenebis(4,1-phenylene)diisocyanate (common name: MDI), 1,3- or 1,4-xylylene diisocyanate or mixtures thereof, ⁇ , ⁇ '-diisocyanato-1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanato-1-methylethyl)benzene (common name: tetramethylxylylene diisocyanate) or mixtures thereof; and aromatic aliphatic triisocyanates such as 1,3,5-triisocyanatomethylbenzene.
• aromatic aliphatic diisocyanates such as methylenebis(4,1-phenylene)diisocyanate (common name: MDI), 1,3- or 1,4-xylylene diisocyanate or mixtures thereof, ⁇ , ⁇ '-diisocyanato-1,4-
• aromatic polyisocyanate examples include aromatic diisocyanates such as m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 2,4-tolylene diisocyanate (common name: 2,4-TDI) or 2,6-tolylene diisocyanate (common name: 2,6-TDI) or mixtures thereof, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate; aromatic triisocyanates such as triphenylmethane-4,4',4''-triisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene; and aromatic tetraisocyanates such as 4,4'-diphenylmethane-2,2',5,5'-tetraisocyanate.
• examples of the derivatives of the polyisocyanates include dimers, trimers, biurets, allophanates, uretdione, uretoimine, isocyanurates, oxadiazinetriones, polymethylene polyphenyl polyisocyanates (crude MDI, polymeric MDI), crude TDI, etc. of the above-mentioned polyisocyanates.
• the derivatives of the polyisocyanates may be used alone or in combination of two or more kinds.
• the above polyisocyanates and their derivatives may be used alone or in combination of two or more kinds.
• hexamethylene diisocyanate compounds and among alicyclic diisocyanates, 4,4'-methylenebis(cyclohexylisocyanate) can be preferably used.
• derivatives of hexamethylene diisocyanate are particularly suitable from the standpoint of adhesion, compatibility, etc.
• the polyisocyanate compound may be a prepolymer obtained by reacting the above polyisocyanate or its derivative with a compound having an active hydrogen group, such as a hydroxyl group or an amino group, which can react with the polyisocyanate under conditions of excess isocyanate groups.
• a compound having an active hydrogen group such as a hydroxyl group or an amino group
• Examples of compounds that can react with the polyisocyanate include polyhydric alcohols, low molecular weight polyester resins, amines, water, etc.
• a blocked polyisocyanate compound which is a compound in which the isocyanate groups in the above polyisocyanates and their derivatives are blocked with a blocking agent, can also be used.
• the above blocking agents include, for example, phenol-based agents such as phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, and methyl hydroxybenzoate; lactam-based agents such as ⁇ -caprolactam, ⁇ -valerolactam, ⁇ -butyrolactam, and ⁇ -propiolactam; aliphatic alcohol-based agents such as methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol, and lauryl alcohol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol monoethyl ether.
• phenol-based agents such as phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonyl
• Ether-based compounds such as ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, and methoxymethanol; alcohol-based compounds such as benzyl alcohol, glycolic acid, methyl glycolate, ethyl glycolate, butyl glycolate, lactic acid, methyl lactate, ethyl lactate, butyl lactate, methylol urea, methylol melamine, diacetone alcohol, 2-hydroxyethyl acrylate, and 2-hydroxyethyl methacrylate; formamide oxime, acetamide oxime, acetoxime, and methyl ethyl ketoxy.
• alcohol-based compounds such as benzyl alcohol, glycolic acid, methyl glycolate, ethyl glycolate, butyl glycolate, lactic acid, methyl lactate, ethyl lactate, butyl lactate, methylol
• oxime-based compounds such as dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, acetylacetone, and other active methylene-based compounds; mercaptan-based compounds such as butyl mercaptan, t-butyl mercaptan, hexyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, methylthiophenol, ethylthiophenol, and other acid amide-based compounds such as acetanilide, acetanisidide, acetotoluide, acrylamide, methacrylamide, acetic acid amide, stearic acid amide, and benzamide; succinic acid amide, ...
• imide-based compounds such as maleic acid imide, phthalic acid imide, and maleic acid imide
• amine-based compounds such as diphenylamine, phenylnaphthylamine, xylidine, N-phenylxylidine, carbazole, aniline, naphthylamine, butylamine, dibutylamine, and butylphenylamine
• imidazole-based compounds such as imidazole and 2-ethylimidazole
• urea-based compounds such as urea, thiourea, ethyleneurea, ethylenethiourea, and diphenylurea
• carbamate-based compounds such as N-phenylphenylcarbamate
• imine-based compounds such as ethyleneimine and propyleneimine
• sulfite-based compounds such as sodium bisulfite and potassium bisulfite
• azole-based compounds such as sodium bisulfite and potassium bisulfite
• azole compounds examples include pyrazoles or pyrazole derivatives such as pyrazole, 3,5-dimethylpyrazole, 3-methylpyrazole, 4-benzyl-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-bromo-3,5-dimethylpyrazole, and 3-methyl-5-phenylpyrazole; imidazoles or imidazole derivatives such as imidazole, benzimidazole, 2-methylimidazole, 2-ethylimidazole, and 2-phenylimidazole; and imidazoline derivatives such as 2-methylimidazoline and 2-phenylimidazoline.
• pyrazoles or pyrazole derivatives such as pyrazole, 3,5-dimethylpyrazole, 3-methylpyrazole, 4-benzyl-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-bromo-3,5-dimethylpyrazole, and 3-methyl-5-
• Solvents used in blocking reactions should be those that are not reactive with isocyanate groups, for example, ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate, and N-methyl-2-pyrrolidone (NMP).
• ketones such as acetone and methyl ethyl ketone
• esters such as ethyl acetate
• NMP N-methyl-2-pyrrolidone
• the polyisocyanate compounds can be used alone or in combination of two or more.
• the equivalent ratio (OH/NCO) of the hydroxyl groups of the hydroxyl-containing resin to the isocyanate groups of the polyisocyanate compound is preferably within the range of 0.5 to 2.0, and more preferably 0.8 to 1.5.
• the hydroxyl-containing resin and the polyisocyanate compound are in a separated form from the standpoint of storage stability, and that the two are mixed together immediately before use.
• a one-component coating may be used.
• Combinations of base resin/curing agent in one-component coatings include carboxyl group-containing resin/epoxy group-containing resin, hydroxyl group-containing resin/blocked polyisocyanate compound, hydroxyl group-containing resin/melamine resin, etc.
• the clear coating (Z) may further contain additives such as solvents such as water or organic solvents, curing catalysts, defoamers, and ultraviolet absorbers, as necessary.
• the above clear coating (Z) can be appropriately blended with a coloring pigment within a range that does not impair transparency.
• a coloring pigment one or a combination of two or more pigments conventionally known for use in inks and coatings can be blended.
• the amount of the pigment to be added can be determined appropriately, but is 30 parts by mass or less, preferably 0.01 to 10 parts by mass, per 100 parts by mass of the vehicle-forming resin composition in the clear coating.
• the form of the clear coating (Z) is not particularly limited, but it is usually used as an organic solvent-based coating composition.
• the organic solvent used may be various organic solvents for coating, such as aromatic or aliphatic hydrocarbon solvents; ester solvents; ketone solvents; ether solvents, etc.
• the organic solvent used may be the same as that used in the preparation of the hydroxyl group-containing resin, etc., or may be added as appropriate.
• the solids concentration of the clear coating (Z) is preferably about 30 to 70% by mass, and more preferably in the range of about 40 to 60% by mass.
• the aforementioned clear paint (Z) is applied onto the glossy coating film.
• the application of the clear paint (Z) is not particularly limited and can be carried out in the same manner as the application of the colored paint (X), for example, by a coating method such as air spray, airless spray, rotary atomization coating, curtain coat coating, etc. These coating methods may be carried out using electrostatic application as necessary. Of these, rotary atomization coating using electrostatic application is preferred.
• the amount of clear paint (Z) applied is usually preferably an amount that results in a cured film thickness of about 10 to 50 ⁇ m.
• the viscosity of the clear coating (Z) it is preferable to adjust the viscosity of the clear coating (Z) appropriately using a solvent such as an organic solvent so that it is in a viscosity range suitable for the coating method, for example, in rotary atomization coating using electrostatic application, the viscosity range is about 15 to 60 seconds when measured at 20°C with a Ford Cup No. 4 viscometer.
• the multi-layer coating film forming method of the present invention includes a step of curing the base coating film, the glossy coating film, and the clear coating film by heating them simultaneously.
• the heating can be performed by known means, for example, a drying oven such as a hot air oven, an electric oven, or an infrared induction heating oven.
• the heating temperature is preferably within the range of 70 to 150°C, and more preferably 80 to 140°C.
• the heating time is not particularly limited, but is preferably within the range of 10 to 40 minutes, and more preferably 20 to 30 minutes.
• the resulting electrocoated surface of the steel plate was then coated with "TP-90 No. 8101 Gray” (product name, manufactured by Kansai Paint Co., Ltd., hydroxyl group/melamine and blocked isocyanate group curing type one-component organic solvent-based paint) using an air spray to a thickness of 40 ⁇ m based on the cured coating film, and after leaving it for 7 minutes, it was heated at 140°C for 30 minutes to form an undercoat coating film, completing the coating process.
• TP-90 No. 8101 Gray product name, manufactured by Kansai Paint Co., Ltd., hydroxyl group/melamine and blocked isocyanate group curing type one-component organic solvent-based paint
• Monomer emulsion 50 parts of deionized water, 10 parts of styrene, 40 parts of methyl methacrylate, 35 parts of ethyl acrylate, 3.5 parts of n-butyl methacrylate, 10 parts of 2-hydroxyethyl methacrylate, 1.5 parts of acrylic acid, 1.0 part of "Aqualon KH-10" and 0.03 parts of ammonium persulfate were mixed and stirred to obtain a monomer emulsion.
• Phosphate group-containing polymerizable monomer 57.5 parts of monobutyl phosphate and 41 parts of isobutanol were placed in a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, and dropping device, and the temperature was raised to 90°C. 42.5 parts of glycidyl methacrylate was then dropped over 2 hours, and the mixture was then further stirred and aged for 1 hour. 59 parts of isopropanol was then added to obtain a phosphate group-containing polymerizable monomer solution with a solids concentration of 50%. The acid value due to the phosphate group of the resulting monomer was 285 mgKOH/g.
• Production Example 7 62.5 parts of the pigment dispersion paste (P-1) obtained in Production Example 4, 54 parts of the glittering pigment dispersion liquid (P-2) obtained in Production Example 5, 44.4 parts (20 parts solids) of the acrylic resin water dispersion (R-1) obtained in Production Example 1, 60 parts (21 parts solids) of "Ucoat UX-8100" (product name, urethane emulsion, manufactured by Sanyo Chemical Industries, Ltd., 35% solids), and 37.5 parts (30 parts solids) of "Cymel 325" (product name, melamine resin, manufactured by Nippon Cytec Industries, 80% solids) were uniformly mixed.
• the remaining monomer emulsion (1) was dropped into the reaction vessel held at the same temperature over 3 hours, and aging was carried out for 1 hour after the end of the dropping.
• the monomer emulsion (2) described below was dropped over 1 hour, and after aging for 1 hour, the reaction vessel was cooled to 30 ° C. while gradually adding 40 parts of a 5% aqueous solution of dimethylethanolamine to the reaction vessel, and the mixture was discharged while filtering through a 100 mesh nylon cloth, to obtain an acrylic resin water dispersion (R-4) having a solid content concentration of 28%.
• the resulting acrylic resin water dispersion (R-4) had a hydroxyl value of 25 mgKOH/g and an acid value of 33 mgKOH/g.
• Monomer emulsion (1) 42 parts of deionized water, 0.72 parts of "Aqualon KH-10", 2.1 parts of methylenebisacrylamide, 2.8 parts of styrene, 16.1 parts of methyl methacrylate, 28 parts of ethyl acrylate, and 21 parts of n-butyl acrylate were mixed and stirred to obtain monomer emulsion (1).
• Monomer emulsion (2) 18 parts of deionized water, 0.31 parts of "Aqualon KH-10", 0.03 parts of ammonium persulfate, 5.1 parts of methacrylic acid, 5.1 parts of 2-hydroxyethyl acrylate, 3 parts of styrene, 6 parts of methyl methacrylate, 1.8 parts of ethyl acrylate, and 9 parts of n-butyl acrylate were mixed and stirred to obtain monomer emulsion (2).
• the mixture was aged at 110 ° C. for 30 minutes, and then an additional catalyst mixture consisting of 25 parts of ethylene glycol monobutyl ether and 0.5 parts of azobisisobutyronitrile was added dropwise over 1 hour.
• the mixture was then aged at 110° C. for 1 hour and then cooled to obtain an acrylic resin solution (R-5) with a solid content of 50%.
• the acrylic resin solution (R-5) had a hydroxyl value of 43 mg KOH/g and a weight average molecular weight of about 20,000.
• the carboxyl group amount of the carboxyl group-containing cellulose nanofiber dispersion (C21-1) was 0.94 mmol/g, the average fiber diameter was 6.9 nm, the average fiber length was 235 nm, and the aspect ratio was 34.
• Example 1 of the preparation of a glittering pigment dispersion Into a stirring mixing vessel, 4,830 parts of distilled water, 15 parts (15 parts solids) of "Dynol-604" (trade name, manufactured by Evonik Industries, acetylene diol-based surface conditioner, solids content 100%), 434.8 parts (200 parts solids) of "Alpaste EMR-B6360” (trade name, manufactured by Toyo Aluminum Co., Ltd., solids content 46%, non-leafing aluminum flakes, average particle size D50: 10.3 ⁇ m, thickness: 0.19 ⁇ m, surface treated with silica), 150 parts (3 parts solids) of phosphoric acid group-containing cellulose nanofiber dispersion (C11-1) (number average fiber diameter 4 nm, amount of phosphoric acid group introduced 1.00 mmol/g, solids concentration 2.0%), 675 parts (27 parts solids) of the carboxyl group-containing cellulose nanofiber dispersion (C21-1) obtained in Production Example 11, and "Primal
• Comparative Example 7 As the glittering pigment dispersion (Y-17), a commercially available "WBC-713T No. 1F7" (product name, manufactured by Kansai Paint Co., Ltd., acrylic melamine resin-based water-based base coat paint, silver paint color, solid content 23%, aluminum pigment-containing, nanocellulose (C)-free) was used.
• WBC-713T No. 1F7 product name, manufactured by Kansai Paint Co., Ltd., acrylic melamine resin-based water-based base coat paint, silver paint color, solid content 23%, aluminum pigment-containing, nanocellulose (C)-free
• Test Plates (1) Preparation of Test Plates for Evaluating Wrinkles, 60° Specular Gloss (60° Gloss) and Flip-Flop Properties Example 11
• the base coating material (X-1) was electrostatically coated on the substrate prepared in the above [1] using a rotary atomizing bell-type coater in a vertical position so that the cured film thickness was 9 ⁇ m, and the substrate was left to stand for 2 minutes to form an uncured base coating film.
• the glitter pigment dispersion (Y-1) prepared in Example 1 was applied vertically onto the uncured base coating using an ABB Robot Bell at a booth temperature of 23°C and humidity of 68% so that the dry coating thickness was 0.7 ⁇ m. After leaving it for 3 minutes, it was preheated vertically at 80°C for 3 minutes to form a glitter coating.
• clear paint (Z-1) was applied vertically onto the uncured glossy coating using an ABB Robot Bell at a booth temperature of 23°C and humidity of 68% so that the dry coating thickness was 35 ⁇ m to form a clear coating.
• the board was left at room temperature for 7 minutes, and then heated vertically at 140°C for 30 minutes in a hot air circulation drying oven to simultaneously dry the multi-layer coating and prepare a test panel for evaluating wrinkles, 60° specular gloss (60° gloss), and flip-flop properties.
• Examples 12 to 21 and Comparative Examples 8 to 14 Test panels for evaluating wrinkles, 60° specular gloss (60° gloss) and flip-flop properties were obtained in the same manner as in Example 11, except that the paint, luster pigment dispersion, and film thickness were as shown in Table 2.
• Example 11 (2) Preparation of test plate for evaluating sagging of vertical portion Example 11 A row of 17 punch holes, each 5 mm in diameter, was made at 2 cm intervals on the long side of the substrate prepared in [1] above, 3 cm from the end of the substrate. Each punch hole was made 10 cm away from the 400 mm long side.
• Base paint (X-1) was electrostatically applied onto the substrate in a vertical position using a rotary atomizing bell-type coater to a cured film thickness of 9 ⁇ m, and the substrate was left to stand for 2 minutes to form an uncured base coating film.
• the photoluminescent pigment dispersion (Y-1) prepared in Example 1 was applied vertically onto the uncured base coating using an ABB robot bell at a booth temperature of 22°C and humidity of 78%, with a film thickness gradient to obtain a dry coating film thickness of approximately 0.5 ⁇ m to 4 ⁇ m in the longitudinal direction, and the coating was left for 3 minutes, after which it was preheated vertically at 80°C for 3 minutes to form a photoluminescent coating film.
• clear paint (Z-1) was applied vertically onto the uncured glossy coating using an ABB Robot Bell at a booth temperature of 23°C and humidity of 68% so that the dry coating thickness was 35 ⁇ m to form a clear coating.
• the panel was left at room temperature for 7 minutes, and then heated vertically at 140°C for 30 minutes in a hot air circulating drying oven to simultaneously dry the multi-layer coating and prepare a test panel for evaluating sagging in the vertical section.
• Example 12 to 21 and Comparative Examples 8 to 14 Test panels for evaluating sagging in vertical portions were obtained in the same manner as in Example 11, except that the paint, the glitter pigment dispersion, and the film thickness were as shown in Table 2.
• Wrinkles The edges of each test plate were visually inspected and rated according to the following criteria: A and B are acceptable. A: No wrinkles are observed, and the coating film has an extremely excellent appearance. B: Almost no wrinkles are observed, and the coating film has an excellent appearance. C: Wrinkles are considerably or significantly observed, and the coating appearance is poor.
• sagging limit film thickness ( ⁇ m)

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