JP2006326538A - Method of forming white pearl coating film and laminated coating film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of forming a white pearl coating film which can obtain a pearl coating film having high flip-flop properties that can recognize that the pearl coating film has the flip-flop properties not only seen closely but seen from a distant, and having an excellent white pearl feeling. <P>SOLUTION: The method of forming the white pearl coating film sequentially forms a white color base coating film, a mica base coating film, and a clear coating film on a substrate formed with a primer coating film and an intermediate coating film. The mica base coating film contains a 3-50 mass% reduced titanium coating interference mica pigment with respect to the total mass of the reduced titanium coating interference mica pigment and a metal oxide coating pigment. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a method for forming a white pearl coating film and a laminated coating film formed by this method.

In fields where high design properties are required, such as automobile bodies, the number of pearl coatings formed from paints containing scaly mica pigments has been increasing year by year in order to meet the need for multicolored top coat colors. Yes. The coated plate on which such a coating film is formed expresses a pearly luster having an interference color when viewed in a nearly vertical state (highlight position), and the pearly luster disappears when the coated plate is viewed obliquely above (shade position). Appears to be white and cloudy. On the other hand, a pearl coating having a flip-flop property that the color tone changes depending on the viewing angle by sequentially laminating a color base coating, a mica base coating, and a clear coating on an object such as an automobile body. I got a film.

However, since the conventional pearl coating film has a small flip-flop property, it can be determined that it is a coating film having a flip-flop property when viewed in the vicinity, but has a flip-flop property when viewed from a distance. It has been difficult to discriminate that it is a coating film, and the whole looks white, that is, there has been a problem that the design property cannot be fully expressed. For this reason, even when viewed from a distance, a coating film having high flip-flop properties has been required.

In Patent Document 1, a color base coating, a mica base coating containing silica, and a clear coating are sequentially applied to a base coated plate, thereby suppressing cloudiness and colorlessness when viewed from the shade position. However, a method for forming a pearl coating film having a pearly feeling, a glittering feeling, and a glittering feeling from any direction is disclosed. However, when viewed from a distance, the obtained pearl coating film has low flip-flop properties.

Patent Document 2 includes a vehicle, an interference mica pigment having a dark region, and other mica pigments, so that when the color of the coating film is a deep color system, the shade portion has no white blurring feeling and is deep. The coating composition which can obtain the glittering coating film which exhibits a certain color tone is disclosed. However, this coating composition forms a coating film having a deep hue, and is not intended to improve the flip-flop property of the white pearl coating film. Also, these documents do not suggest a method for forming a pearl coating film having a good white pearl feeling with a high brightness as well as a high flip-flop property when the color base is particularly white.

JP 2001-170559 A JP 2001-164197 A

In view of the present situation, the present invention has a high flip-flop property so that it can be determined that it is a pearl coating film having a flip-flop property not only when viewed from close, but also when viewed from a distance, and An object of the present invention is to provide a method for forming a white pearl coating film from which a pearl coating film having an excellent white pearl feeling can be obtained.

The present invention provides a white pearl coating film forming method for sequentially forming a white color base coating film, a mica base coating film, and a clear coating film on a substrate on which an undercoat coating film and an intermediate coating film are formed. The base coating film contains the reduced titanium-coated interference mica pigment in an amount of 3 to 50% by mass based on the total mass of the reduced titanium-coated interference mica pigment and the metal oxide-coated pigment. It is a forming method.

The reduced titanium-coated interference mica pigment is formed by sputtering the interference mica pigment (A) coated with a titanium compound containing low-order titanium oxide and then coated with titanium dioxide, and / or metal titanium after coating the surface with a titanium dioxide layer. And it is preferable that it is an interference mica pigment (B) in which the metal titanium part and the low-order titanium oxide part which reduced a part of titanium dioxide film are scattered on the surface.

The present invention is also a laminated coating film characterized by being formed by the above-described white pearl coating film forming method.
The present invention is described in detail below.

White pearl coating film forming method The white pearl coating film forming method of the present invention comprises a white color base coating film, a specific amount of reduced titanium coat interference mica on a substrate on which an undercoat film and an intermediate coating film are formed. Since the mica base coating film containing the pigment and the metal oxide-coated pigment and the clear coating film are sequentially formed, a white pearl coating film having high flip-flop properties can be formed. For this reason, even if this formed coating film is viewed from near or from a distance, the color tone appears to change depending on the viewing angle. Further, this coating film has an excellent white pearly color sensation.

The white pearl coating film forming method of the present invention is a method of sequentially forming a white color base coating film, a mica base coating film, and a clear coating film on a substrate on which an undercoat coating film and an intermediate coating film are formed.

White color base coating film In the white pearl coating film forming method of the present invention, the white color base coating film is a coating film formed on a substrate on which an undercoat film and an intermediate coating film are formed. Color can be added to the material. A white color base paint is used to form the white color base coating film.
Examples of the white color base paint include those containing a color pigment, a film-forming resin, a curing agent, an organic amide, and crosslinked resin particles.

Examples of the color pigment include white pigments such as titanium dioxide.
The content of the white pigment is preferably a lower limit of 30% and an upper limit of 75% in terms of pigment concentration (PWC). If it is less than 30%, the base concealing property may be lowered. If it exceeds 75%, the appearance may deteriorate. By containing the white pigment in the above range, a so-called white color base coating film having a Munsell value of N7 to N9.5 can be formed. The lower limit is more preferably 40%, and the upper limit is more preferably 65%.

The white color base paint may contain other pigments as long as the whiteness of the coating film is not impaired. Examples of the other pigments include azo lake pigments, insoluble azo pigments, condensed azo pigments, diketopyrrolopyrrole pigments, benzimidazolone pigments, phthalocyanine pigments, indigo pigments, perinone pigments, and perylene pigments. Organic color pigments such as dioxazine pigments, quinacridone pigments, isoindolinone pigments, metal complex pigments; inorganic color pigments such as yellow lead, yellow iron oxide, bengara, carbon black; calcium carbonate, barium sulfate, clay And extender pigments such as talc.

Examples of the film-forming resin include acrylic resins, polyester resins, alkyd resins, and fluorine resins.
As the curing agent, for example, a curing agent such as an amino resin and / or a block polyisocyanate compound is used.
The solid content of the coating film-forming resin and the curing agent in the white color base paint is preferably in the range of 30 to 70% by mass during production and 10 to 50% by mass during application.

As said organic amide, what is generally known as a viscosity control agent for providing thixotropic property can be mentioned. Specifically, for example, fatty acid amide can be exemplified, and examples of commercially available products include those in a powder state and in a paste state. In general, the paste is diluted with a solvent such as xylene or alcohol.

Examples of the fatty acid amide include diamide and polyamide. Diamide is a compound obtained by reacting a diamine with a hydroxyl group-containing fatty acid. Polyamide is a compound obtained by reacting a polybasic carboxylic acid, a diamine, and a hydroxyl group-containing fatty acid. The number average molecular weight (Mn) of the fatty acid amide is generally preferably 1000 to 2000.

The content of the organic amide is preferably a lower limit of 0.1 parts by mass and an upper limit of 10 parts by mass with respect to 100 parts by mass of the resin solid content in the white color base paint. If it is less than 0.1 part by mass, the effects of the present invention cannot be sufficiently obtained, and the appearance of the coating film such as gloss and color may be deteriorated. If it exceeds 10 parts by mass, the coating film may become rough and the coating film performance may be reduced. The lower limit is more preferably 0.3 parts by mass, and still more preferably 0.5 parts by mass. The upper limit is more preferably 5 parts by mass, and still more preferably 3 parts by mass.

As the cross-linked resin particles, those generally known as viscosity control agents can be used. For example, resin particles called NAD (Non Aqueous Dispersion) can be used. As an example of this, resin particles used in the NAD paint described in Coloring Materials, Vol. 48 (1975), pages 28-34 can be mentioned. Moreover, the polymerizable resin particles disclosed in JP-A-53-133236 can be used as the crosslinked resin particles in the white color base paint.

Among the above, those that are insoluble in organic solvents and do not affect gloss and color developability when formed into a coating are preferred, and non-crosslinked or crosslinked resins or particles that utilize the interaction of polar groups are particularly preferred. preferable. Most preferred is one obtained by polymerizing a monomer in the presence of a polyester resin having a zwitterionic group.

The cross-linked resin particles also include a resin having an emulsifying ability such as an alkyd resin or a polyester resin synthesized using a monomer having a zwitterionic group in the molecule as one of the polyhydric alcohol components, and a polymerization initiator. Those obtained by emulsion polymerization of an ethylenically unsaturated monomer in an aqueous medium in the presence of
The crosslinked resin particles obtained by this method are generally contained in an emulsion resin, do not contain low molecular emulsifiers or protective colloids that degrade performance when formed into a coating film, and two or more radical polymerizations in the molecule. Since it is crosslinked by copolymerizing monomers having possible ethylenically unsaturated groups, the water resistance, solvent resistance and gloss of the coating film are excellent.

The content of the crosslinked resin particles is preferably a lower limit of 2 parts by mass and an upper limit of 20 parts by mass with respect to 100 parts by mass of the resin solid content in the white color base paint. If it is less than 2 parts by mass, the coating film appearance such as gloss and color may be deteriorated. If it exceeds 20 parts by mass, the coating film may become rough and the coating film performance may be reduced. The lower limit is more preferably 4 parts by mass, and still more preferably 6 parts by mass. The upper limit is more preferably 17 parts by mass and even more preferably 15 parts by mass.

In the white color base paint, the blending ratio of the organic amide and the crosslinked resin particles is preferably 1/50 to 1.5 / 1 in terms of the solid content of the organic amide / crosslinked resin particles. When the amount of the organic amide in the blending ratio is small, the glossiness or color feeling in the coating film appearance may be lowered. Moreover, when there is too much quantity of the organic amide in a compounding ratio, there exists a possibility that coating-film performance may fall. The blending ratio is more preferably 1/20 to 1/1.

The total content of the organic amide and the crosslinked resin particles is preferably 2 parts by mass and 30 parts by mass with respect to 100 parts by mass of the resin solid content in the white color base paint. If it is less than 2 parts by mass, the gloss and color appearance in the coating film appearance may be reduced, and if it exceeds 30 parts by mass, the coating film may be roughened and the coating film performance may be reduced. The lower limit is more preferably 4 parts by mass, and still more preferably 6 parts by mass. The upper limit is more preferably 20 parts by mass, and still more preferably 16 parts by mass.

If desired, the white color base paint may contain other additives. Examples of such additives include surface conditioners such as silicone and organic polymers, ultraviolet absorbers, hindered amines, hindered phenols, and the like.

The white color base paint may be any of organic solvent type, aqueous type (water-soluble, water-dispersible, emulsion), non-aqueous dispersion type or powder type, and if necessary, a curing catalyst, a surface conditioner, etc. Can be used.

The method for producing the white color base paint is not particularly limited, and methods well known to those skilled in the art such as kneading and dispersing a compound such as a pigment using a kneader or a roll can be applied.
Examples of commercially available white color base paints include Olga P-30 white color base paint, Superlac M-155HS (all of which are manufactured by Nippon Paint Co., Ltd.).

Mica base coating film In the method for forming a white pearl coating film of the present invention, the mica base coating film is formed on the above-described white color base coating film. And glitter and flip-flop properties can be imparted. A mica base paint is used to form the mica base coating film.

The mica base paint contains a reduced titanium-coated interference mica pigment and a metal oxide-coated pigment. Examples of the mica-based paint include those containing a metal oxide-coated pigment, a reduced titanium-coated interference mica pigment, a film-forming resin, a curing agent, and crosslinked resin particles.

The metal oxide-coated pigment has a surface of alumina flake or mica pigment such as TiO ₂ , SnO ₂ , ZrO ₂ , Fe ₂ O ₃ , ZnO ₂ , Cr ₂ O ₃ , V ₂ O _5, or their hydrates. Interference alumina flake pigments coated with metal oxides, colored alumina flake pigments, etc. or white alumina flake pigments.
The above-mentioned metal oxide-coated pigment has a pearly foil shape, metal-like and iridescent effect, and also brings about a color feeling exhibited by the thickness of the metal oxide species and its coating layer. Especially, what was uniformly coat | covered with metal oxides, such as titanium dioxide and iron oxide, is preferable.

While the metal oxide-coated pigments shape is not particularly limited, for example, preferably those scaly, the average particle size (D ₅₀₎ 2 to 50 [mu] m, is preferable and a thickness is 0.1~3μm .

Examples of commercially available pigments that give an interference color include, for example, Shiralik T60-10 W3 (trade name, manufactured by Merck Japan) having a white interference color, and Pearl Grace SME 90-9 (trade name, manufactured by Nippon Koken Co., Ltd.). ), Iriodin Ultra 7235 W2 having a green interference color (trade name, manufactured by Merck Japan), Iriodin Ultra 7225 W2 having a blue interference color (trade name, manufactured by Merck Japan), Iriodin Ultra having an interference color of yellow 7205 W2 (trade name, manufactured by Merck Japan Ltd.).

In addition, when using the white color base coating film of the above-mentioned Munsell value N7-N9.5 as a white color base coating film, as a luster material of a mica base coating material, Shiraruk T60-10 W3 (trade name, manufactured by Merck Japan) A pigment having a white interference color such as Pearl Grace SME 90-9 (trade name, manufactured by Nippon Koken Co., Ltd.) is preferred. Thereby, a white pearl feeling can be obtained suitably. Moreover, when the mica base coating film using the interference mica pigment having the white interference color is formed on the white color base coating film having a Munsell value of N7 to N9.5, the flip-flop property can be further improved. Therefore, even when the obtained white pearl coating (laminated coating) is viewed from a distance, it can be determined that the coating has flip-flop properties.

In general, the pigment concentration (PWC) of the metal oxide-coated pigment in the mica base paint is preferably 18.0% or less. If it exceeds 18.0%, the coating film appearance may be deteriorated. The PWC is more preferably 0.01 to 17.0%, still more preferably 0.01 to 16.0%.

The mica base paint contains a reduced titanium-coated interference mica pigment.
The reduced titanium-coated interference mica pigment is a pigment that emits an interference color in which the surface of the mica pigment is coated with partially reduced titanium oxide. When a mica base coating is formed by applying a mica base coating containing the reduced titanium coat interference mica pigment and the metal oxide coating pigment on the white base coating, a high flip-flop property is obtained. A white pearl coating film can be obtained. For this reason, even if it sees from a distance, it can discriminate | determine that it is a coating film which has flip-flop property. At the same time, a white pearl coating film having excellent white feeling and pearl feeling can be obtained.

The reduced titanium-coated interference mica pigment is formed by sputtering the interference mica pigment (A) coated with a titanium compound containing low-order titanium oxide and then coated with titanium dioxide, and / or metal titanium after coating the surface with a titanium dioxide layer. And it is preferable that it is an interference mica pigment (B) in which the metal titanium part and the low-order titanium oxide part which reduced a part of titanium dioxide film are scattered on the surface. By using the reduced titanium-coated interference mica pigments (A) and (B) in combination with the metal oxide-coated pigment, the white pearl coating film can improve the flip-flop property of the coating film and has an excellent white feeling. Can be obtained.

The reduced titanium-coated interference mica pigment (A) is an interference mica pigment obtained by coating the surface of a mica pigment with a titanium compound containing low-order titanium oxide and then coating with titanium dioxide. The reduced titanium-coated interference mica pigment (B) is obtained by coating the surface of the mica pigment with titanium dioxide, and further reducing the metal titanium portion and a part of the titanium dioxide film on the surface by sputtering using metal titanium. It is an interference mica pigment obtained by processing so as to be interspersed with the next titanium oxide part.
The low-order titanium oxide is represented by the general formula TiO _a (a = 1 to 1.99), and examples thereof include Ti ₂ O ₃ , Ti ₃ O ₅ , and TiO. .

The shape of the reduced titanium-coated interference mica pigment is preferably scaly.
The average particle size of the scale-like reduced titanium-coated interference mica pigment is preferably a lower limit of 5 μm and an upper limit of 44 μm. If it is less than 5 μm, the resulting coating film may have low flip-flop properties. On the other hand, when it exceeds 44 micrometers, there exists a possibility that the coating-film external appearance may fall resulting from the smoothness fall of a coating film. The lower limit is more preferably 8 μm, still more preferably 10 μm. The upper limit is more preferably 40 μm and even more preferably 25 μm. The average particle size is measured by a laser diffraction method.
The average particle size is a volume average particle size. The average thickness of the scale-like reduced titanium-coated interference mica pigment is preferably 0.1 to 3.0 μm. In addition, the measuring method of the said average thickness is based on an electron microscope observation. The average thickness is a number average thickness.

The color of each reduced titanium-coated interference mica pigment can be obtained by adjusting the type and amount (coating thickness) of the metal oxide to be coated. Further, each of these reduced titanium-coated interference mica pigments may be further coated with an oxide such as tin, zirconium, chromium, or silicon in order to improve weather resistance and water resistance. .

As a commercial item of the reduced titanium-coated interference mica pigment, for example, for the reduced titanium-coated interference mica pigment (A), Iriodin 605W2, Iriodin 602W2, Iriodin 612W2 (above, manufactured by Merck & Co., Inc.), INFINITE COLOR GB-06, Examples include INFINITE COLOR CB-06, INFINITE COLOR BP-15 (manufactured by Shiseido Co., Ltd.), L-6000 (manufactured by BASF Corp.), and the like. Examples of the reduced titanium-coated interference mica pigment (B) include TISPAL 235 (manufactured by Nisshin Steel Co., Ltd.).

In the mica base coating obtained by using the mica base coating, the content of the reduced titanium coat interference mica pigment is such that the reduced titanium coat interference mica pigment contained in the mica base coating and the metal oxide coating pigment In the total mass of 100% by mass, the lower limit is 3% by mass and the upper limit is 50% by mass. By forming a mica base coating film containing the reduced titanium-coated interference mica pigment and metal oxide-coated pigment in an amount within the above range on the white color base coating film, high flip-flop properties can be imparted. For this reason, even when viewed from a distance, it can be determined that the obtained white pearl coating film has flip-flop properties. Moreover, the obtained white pearl coating film has an excellent white feeling. If it is less than 3% by mass, the flip-flop property is lowered. When it exceeds 50 mass%, the coating film obtained will color and a hue feeling will come to differ. The lower limit is preferably 8% by mass, and the upper limit is preferably 30% by mass.

The pigment concentration (PWC) of only the reduced titanium-coated interference mica pigment in the mica base paint is generally preferably 5.0% or less. If it exceeds 5.0%, the color is changed to such an extent that the hue changes, the film thickness dependency of the coating film becomes high, and the hue stability may be lowered. The pigment concentration is more preferably 0.01 to 4.8%.

In the mica-based paint, the film-forming resin is not particularly limited, and examples thereof include the same film-forming resin as that contained in the white color base paint. The film-forming resin is preferably dissolved or dispersed in an aqueous medium.

In the mica base paint, the cross-linked resin particles may be the same as the cross-linked resin particles contained in the white color base paint. By containing the crosslinked resin particles, there is an advantage that the coating workability becomes easy.

In the mica-based paint, the content of the crosslinked resin particles is preferably 0.01 parts by mass and 10 parts by mass with respect to 100 parts by mass of the resin solid content of the mica-based paint. If the amount is less than 0.01 parts by mass, the viscosity control effect cannot be obtained, and there is a possibility of causing familiarity or inversion between layers. If it exceeds 10 parts by mass, the appearance may be deteriorated. The lower limit is preferably 0.02 parts by mass, and more preferably 0.03 parts by mass. The upper limit is more preferably 8 parts by mass, and still more preferably 6 parts by mass.

The total solid content of the mica-based paint is preferably 10% by mass lower limit and 60% by mass upper limit. The lower limit is more preferably 15% by mass, and the upper limit is 55% by mass. More preferred.
The paint form of the mica base paint may be any of organic solvent type, aqueous type (water-soluble, water-dispersible, emulsion), and non-water-dispersed type. If necessary, a curing catalyst, an ultraviolet absorber, and an antioxidant. A surface conditioner or the like can be used.

The method for producing the mica base paint is not particularly limited as in the above-described method for producing the white color base paint, and is well known to those skilled in the art such as kneading and dispersing a compound such as a pigment using a kneader or a roll. The method can be applied.

Clear coating film In the method for forming a white pearl coating film of the present invention, the clear coating film is formed on the above-mentioned mica base coating film and can protect the surface of the coating film.
A clear coating is used to form the clear coating film. Examples of the clear paint include those containing a film-forming resin and a curing agent.

In the clear paint, the film-forming resin is not particularly limited, and a film-forming resin such as an acrylic resin, a polyester resin, an epoxy resin, or a urethane resin can be used. It can be used in combination with a curing agent such as a resin and / or a blocked isocyanate resin. Among these, from the viewpoint of transparency or acid etching resistance, a combination of an acrylic resin and / or a polyester resin and an amino resin, an acrylic resin having a carboxylic acid / epoxy curing system, and / or a polyester resin are preferable.

The content of the coating film-forming resin in the clear coating is preferably 20% by mass for the lower limit and 60% by mass for the upper limit in 100% by mass of the resin solid content. The lower limit is more preferably 35% by mass, and the upper limit is more preferably 55% by mass. Moreover, it is preferable that it is 10-50 mass%, and, as for solid content at the time of application | coating, it is more preferable that it is 20-50 mass%.

The clear paint preferably also contains crosslinked resin particles. By containing the crosslinked resin particles, after applying the mica base paint, the clear paint is applied in an uncured state. It is possible to prevent familiarity, inversion or sagging between the two layers.
Examples of the crosslinked resin particles include those similar to the crosslinked resin particles contained in the above white base paint.

The content of the crosslinked resin particles is preferably a lower limit of 0.01 parts by mass and an upper limit of 10 parts by mass with respect to 100 parts by mass of the resin solid content of the clear coating. If it is less than 0.01 parts by mass, the viscosity control effect cannot be obtained and there is a risk of causing problems such as sagging. If it exceeds 10 parts by mass, the appearance may be deteriorated. The lower limit is more preferably 0.02 parts by mass, and still more preferably 0.03 parts by mass. The upper limit is more preferably 8 parts by mass, and still more preferably 6 parts by mass.

The clear coating composition may be any of organic solvent type, aqueous type (water-soluble, water-dispersible, emulsion), non-aqueous dispersion type, and powder type. If necessary, a curing catalyst, a surface conditioner, etc. Can be used.

The method for producing the clear paint is not particularly limited as in the above-described method for producing the white color base paint, and is a method well known to those skilled in the art, such as kneading and dispersing a compound such as a resin using a kneader or a roll. Can be applied.
Examples of commercially available clear paints include Superlac O-1810 Clear and Superlac O-150 (manufactured by Nippon Paint Co., Ltd.).

In the white pearl coating film forming method of the present invention, the white color base coating material is applied on a substrate on which an undercoat coating film and an intermediate coating film are formed and cured, and then wet-on-wet mica base coating material and clear coating film are formed. The coating film is preferably formed by a 3-coat 2-bake method in which paints are applied in this order and simultaneously cured.
At the same time, the present invention can be applied to the following 3-coat 1-bake coating method. That is, first, a color base is applied on a substrate on which an undercoat film and an intermediate coat film are formed, then a mica base paint is applied by wet-on-wet, and then a clear paint is applied by wet-on-wet. This is a coating film forming method in which the layers are simultaneously cured.

In the case of forming a white pearl paint film by the above-mentioned 3 coat and 2 bake, the white color base paint is applied by, for example, an air electrostatic spray paint in order to improve the design when it is applied to an automobile body or the like. Stage coating, preferably a two-stage coating method, or air electrostatic spray coating and a so-called “μμ (micro micro) bell”, “μ (micro) bell” or “metabell” or the like. It is preferable that the coating method be combined with an electrostatic coating machine.

In the method of curing the white color base paint after coating, the curing temperature is preferably 100 to 180 ° C. If it is less than 100 degreeC, there exists a possibility that hardening may be inadequate. If it exceeds 180 ° C, the coating film may become hard and brittle. The curing temperature is more preferably 120 to 160 ° C. Although hardening time changes with hardening temperature, when it is 120-160 degreeC, it is preferable that it is 10 to 30 minutes.

The dry film thickness of the white color base coating film formed by application of the white color base paint varies depending on the desired application, but in many cases, the lower limit is preferably 20 μm and the upper limit is 60 μm. If it is less than 20 μm, the underlying layer cannot be concealed and there is a risk of film breakage. If it exceeds 60 μm, there is a risk of problems such as flow during painting. The lower limit is more preferably 25 μm, and the upper limit is more preferably 45 μm.

In the case of forming a white pearl coating film by the above-mentioned 3 coats and 2 bakes, after forming a cured white color base coating film, a mica base coating and a clear coating are applied on the coating film in this order by wet on wet, A cured mica base coating and clear coating are formed by curing the formed uncured mica base coating and clear coating.

Examples of the method for applying the mica base paint include a method of applying the above-described rotary atomizing electrostatic coater in the same manner as the white color base paint, and the dry film thickness of the mica base coating film to be formed. The lower limit is preferably 8 μm and the upper limit is 30 μm. If it is less than 8 μm, there is a possibility that the design property by the mica pigment cannot be obtained sufficiently. If it exceeds 30 μm, the sharpness may be deteriorated, or a problem such as flow may occur. The lower limit is more preferably 10 μm, and the upper limit is more preferably 20 μm.

As the coating method of the clear paint, a method of coating with the above-described rotary atomizing electrostatic coater is preferable, as with the white color base paint.
As for the dry film thickness of the clear coating film formed with the said clear coating material, generally the minimum of 20 micrometers and the upper limit of 70 micrometers are preferable. If it is less than 20 μm, there is a possibility that the concavity and convexity of the foundation is insufficiently concealed. If it exceeds 70 μm, there is a risk of problems such as cracking or sagging during coating. The lower limit is more preferably 25 μm, and the upper limit is more preferably 60 μm.

In the method of curing the mica base paint and the clear paint and then curing them, the curing temperature is preferably a lower limit of 100 ° C. and an upper limit of 180 ° C. If it is less than 100 ° C, curing may be insufficient. If it exceeds 180 ° C, the coating film may become hard and brittle. The lower limit is more preferably 120 ° C. and the upper limit is more preferably 160 ° C. in that a cured coating film having a high degree of crosslinking can be obtained. Although hardening time changes with hardening temperature, in the case of 120-160 degreeC, 10-30 minutes are preferable. When the mica base paint and the clear paint are applied by wet-on-wet, and simultaneously cured to form a cured coating film, a process (preheating) is performed in which water is evaporated at 40 to 100 ° C. for 1 to 10 minutes after the mica base paint is applied. ) Is preferable.

The white pearl coating film forming method of the present invention is a method applied to a substrate on which an undercoat film and an intermediate coat film are formed.
Substrate Examples of the substrate include wood, metal, glass, cloth, plastic, foam and the like, particularly metal surfaces and castings. In particular, metal products capable of cationic electrodeposition coating are preferred.

Examples of the metal products include iron, copper, aluminum, tin, zinc, and alloys containing these metals. Specific examples include automobile bodies and parts such as passenger cars, trucks, motorcycles, and buses. These metals are more preferably those which have been previously subjected to chemical conversion treatment with phosphate, chromate or the like.

Undercoat coating film The undercoat coating film is a coating film formed on a substrate, whereby corrosion of the substrate can be prevented. As the electrodeposition paint for forming the undercoat coating film, a cationic electrodeposition paint and an anionic electrodeposition paint can be used, but a cationic type is preferable from the viewpoint of providing a multilayer coating film excellent in corrosion resistance. Examples of commercially available electrodeposition paints include Power Top U-50, Power Nix 100 (manufactured by Nippon Paint Co., Ltd.), and the like.

Intermediate coating film The intermediate coating film is formed on the undercoating film, conceals the underlying defects, ensures the surface smoothness after the top coating (improves appearance), and the physical properties of the coating film ( Impact resistance, chipping resistance, etc.). An intermediate coating is used to form the intermediate coating. Examples of the intermediate coating include those containing a pigment, a film-forming resin, and a curing agent.

In the intermediate coating, the pigment may be any organic or inorganic colored pigment or extender, for example, the same as the various colored pigments or extender contained in the white color base paint. Can be mentioned. Further, flat pigments such as aluminum powder and graphite powder may be used. As a standard, a gray intermediate coating with carbon black and titanium dioxide as main pigments is used. Furthermore, a so-called color intermediate coating composition in which set gray or various colored pigments are combined can also be used.

In the intermediate coating composition, the coating film-forming resin is not particularly limited, and examples thereof include the same coating film-forming resin contained in the above-described white color base coating material. Especially, what combined the alkyd resin and / or polyester resin, and the amino resin from the point of pigment dispersibility or workability | operativity is preferable.
Examples of commercially available intermediate coating materials include Olga P-2 gray, Olga P-30 gray (manufactured by Nippon Paint Co., Ltd.), and the like.

In the white pearl coating film forming method of the present invention, after the intermediate coating material is applied onto the substrate on which the undercoat coating film is formed, the next white color base coating material can be further applied even in an uncured state. However, when the intermediate coating film is cured, the curing temperature is preferably a lower limit of 100 ° C. and an upper limit of 180 ° C. in that a cured coating film having a high degree of crosslinking can be obtained. If it is less than 100 ° C, curing may be insufficient. If it exceeds 180 ° C, the coating film may become hard and brittle. The lower limit is more preferably 120 ° C., and the upper limit is more preferably 160 ° C. Although the said hardening time changes with hardening temperature, in the case of hardening temperature 120-160 degreeC, 10 to 30 minutes are preferable.

The film thickness of the laminated coating film formed by the method for forming a white pearl coating film of the present invention is preferably a lower limit of 30 μm and an upper limit of 300 μm. If it is less than 30 μm, the strength of the film itself may be reduced, and if it exceeds 300 μm, film properties such as a cooling cycle may be reduced. The lower limit is more preferably 50 μm, and the upper limit is more preferably 250 μm.

Laminated coating film The laminated coating film formed by the method of forming a white pearl coating film of the present invention has excellent white pearl color and high flip-flop properties. For this reason, it is possible to discriminate that the laminated coating film is a white pearl coating film having flip-flop properties, not only when viewed from the vicinity but also when viewed from a distance. Such a laminated coating film is also one aspect of the present invention.

The white pearl coating film forming method of the present invention sequentially forms a mica base coating film and a clear coating film containing specific amounts of the reduced titanium-coated interference mica pigment and the metal oxide-coated pigment on a white color base coating film. Is the method. Thereby, even when viewed from a distance, it is possible to form a laminated coating film having high flip-flop properties and high brightness and an excellent white pearl feeling.

Since the white pearl coating film forming method of the present invention has the above-described configuration, it is possible to form a white pearl coating film having high flip-flop properties and excellent white pearl color. Therefore, by applying the above-mentioned white pearl coating film forming method to automobile bodies, parts, etc., it is possible to enhance the high-quality appearance.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited only to these examples. In the following examples, “part” or “%” means “part by mass” and “% by mass”, respectively.

[Production Example 1]
(Manufacture of white color base paint)
Using an Olga P-30 white color base paint (trade name, manufactured by Nippon Paint Co., Ltd.) No. The viscosity was adjusted with a 4 Ford cup. The white pigment content (PWC) is 45% by mass.

[Production Example 2]
(Manufacture of film-forming resin)
Into a 2 L reaction vessel equipped with a nitrogen introduction tube, a stirrer, a temperature controller, a dropping funnel and a cooling tube, 450 parts of propylene glycol ethyl ether was charged to a temperature of 107 ° C. Next, 100 parts of acrylamide was dissolved in 200 parts of propylene glycol methyl ether, and 50 parts of styrene, 200 parts of 2-ethylhexyl methacrylate, 313 parts of n-butyl acrylate, 77 parts of methacrylic acid, Plaxel FM-1 (trade name, hydroxyl group) A monomer solution was separately prepared by mixing 260 parts of a polymerizable monomer (manufactured by Daicel Corporation) and 8 parts of t-butylperoxy-2-hexanoate. This monomer solution was dropped into the reaction vessel over 3 hours with stirring, and then stirring was continued for 30 minutes. Further, a mixed solution of 5 parts of t-butylperoxy-2-hexanoate and 50 parts of propylene glycol methyl ether was added. After dropwise addition over 15 minutes, stirring was continued for 1 hour to obtain an acrylic resin having a resin solid content of 59%, a number average molecular weight of 13,000, a hydroxyl value of 60, and an acid value of 50 mgKOH / g.
Solvent 500 parts of this acrylic resin was removed until the resin solid content became 75%, and 23.4 parts of dimethylethanolamine and 925 parts of ion-exchanged water were added to obtain a water-soluble acrylic resin having a resin solid content of 22%. It was.

[Production Example 3]
(Manufacture of mica base paint)
To 273 parts of the water-soluble acrylic resin obtained in Production Example 2 above, 9.9 parts of “Silary T60-10W3” (white interference alumina flake pigment, average particle size 19 μm, manufactured by Merck Japan Ltd.) and “Iriodin 605W2” ( 1.2 parts of reduced titanium-coated interference mica pigment, average particle size 18 μm, manufactured by Merck Japan Ltd.) and uniformly dispersed, and further 50 parts of melamine resin “Cymel 202” (Mitsui Cytec Co., Ltd.) and acrylic surface conditioner 0.20 part was added and uniformly dispersed to obtain a mica base paint.

[Example 1]
(Formation method of coating film)
Cathodic electrodeposition paint “Power Top U-50” (manufactured by Nippon Paint Co., Ltd.) is electrodeposited onto a dull steel plate with a thickness of 0.8 cm and 20 cm × 30 cm treated with zinc phosphate to a dry film thickness of 20 μm. And baked at 160 ° C. for 30 minutes. Next, on the obtained electrodeposition coating film, a gray intermediate coating “Orga P-2 Gray” (polyester / melamine resin-based paint, manufactured by Nippon Paint Co., Ltd.) is applied so that the dry film thickness becomes 30 μm. Spray coating was performed, and a base coating film was baked at 140 ° C. for 20 minutes.
On the obtained intermediate coating film, the “auto REA” (manufactured by Landsburg) is applied to the white color base paint obtained in Production Example 1 described above in two stages at intervals of 2 minutes so that the dry film thickness becomes 15 μm. The air electrostatic coating machine was applied, and after an interval of 8 minutes, it was baked and cured at 140 ° C. for 20 minutes. The hue of the obtained white color base coating film was N9 in Munsell display.
Further, the mica base paint obtained in Production Example 3 was applied in two stages so that the dry film thickness was 15 μm. An interval of 1.5 minutes was performed between the two applications. After the second application, setting was performed for 3 minutes, followed by preheating at 80 ° C. for 3 minutes. In addition, the clear paint "Super Lac O-1810 Clear" (acid / epoxy curable acrylic resin paint, manufactured by Nippon Paint Co., Ltd.) is rotated and atomized electrostatically coated with a μμ bell so that the dry film thickness becomes 30 μm. did. Then, it baked for 20 minutes at 140 degreeC, and created the coating film for evaluation.

[Examples 2 to 5, Comparative Examples 1 to 5]
A coating film for evaluation was prepared in the same manner as in Example 1 except that the contents of “Silary T60-10W3” and “Iriodin 605W2” in the mica-based paint were changed as shown in Table 1.

〔Evaluation methods〕
(Flip-flop (FF))
Using a Minolta color change colorimeter 512-M3 (manufactured by Minolta Co., Ltd.), flip-flop properties were evaluated from L values of the respective coating films at 25 degrees and 75 degrees with respect to incident light. The flip-flop property was obtained by (L value at 25 degrees) / (L value at 75 degrees).
Moreover, about the obtained coating film, the following reference | standard evaluated the presence or absence of flip-flop property visually.
◎: FF property is present 〇: FF property is present △: FF property is present ×: FF property is not present (lightness)
The L value of each coating film for evaluation at 25 degrees with respect to incident light was measured using a Minolta color change color difference meter 512-M3 (manufactured by Minolta).
(Color sense)
The color feeling of each obtained coating film for evaluation was visually evaluated according to the following criteria.
◯: There is a white feeling △: Feels slightly gray ×: Feels gray

From Table 1, in the examples, a laminated coating film having high flip-flop properties and good white feeling was obtained, but in the comparative example, a coating film having both high flip-flop properties and white feeling was not obtained.

The white pearl coating film forming method of the present invention can be suitably applied to automobile bodies and parts.

Claims (3)

A white pearl coating film forming method for sequentially forming a white color base coating film, a mica base coating film, and a clear coating film on a base material on which an undercoat coating film and an intermediate coating film are formed,
The mica base coating film contains 3-50% by mass of reduced titanium-coated interference mica pigment with respect to the total mass of the reduced titanium-coated interference mica pigment and the metal oxide-coated pigment. Coating film forming method. The reduced titanium-coated interference mica pigment is formed by sputtering the interference mica pigment (A) coated with a titanium compound containing low-order titanium oxide and then coated with titanium dioxide, and / or metal titanium after coating the surface with a titanium dioxide layer. 2. The method for forming a white pearl coating film according to claim 1, which is an interference mica pigment (B) interspersed with a titanium metal portion and a low-order titanium oxide portion obtained by reducing a part of the titanium dioxide film on the surface. It forms with the white pearl coating-film formation method of Claim 1 or 2, The laminated coating film characterized by the above-mentioned.