JP2018001060A - Coating method - Google Patents

Abstract

An object of the present invention is to provide a painting method capable of sufficiently reducing the color difference between a resin member and a metal member after painting.
The ratio of the average primary particle diameter of the resin additive to the average primary particle diameter of the metal additive is set to 0.8 or more and 1.2 or less. Then, a resin clear paint containing a resin additive is applied on the base coating film to form a resin clear coating, and a metal clear paint containing a metal additive is applied on the base coating film. Apply to form a clear coating for metal.
[Selection] Figure 1

Description

  The present invention relates to a painting method, and more particularly to a vehicle painting method.

  Generally, in a vehicle, a resin member such as a plastic bumper or a plastic fender is attached to a metal member such as a vehicle frame.

  Conventionally, in resin coating, the heat resistance of a resin member is lower than that of a metal member. Therefore, each of the metal member and the resin member is coated in a separate process with paint and conditions according to the heat resistance, and then the resin The member is assembled to the metal member.

  That is, in the metal member coating process, a coating for a metal member that cures at a relatively high temperature is applied to the metal member and cured, and in the coating process for the resin member, a coating for a resin member that cures at a relatively low temperature. The resin member is applied and cured.

  For example, an automobile body made of a metal steel plate is coated with a paint for a metal steel plate and a clear paint and baked at 120 to 140 ° C., and a bumper made of a resin material is coated with a paint for a resin member and a clear paint at 90 to 110 ° C. There has been proposed a method of painting a vehicle that is baked in (see, for example, Patent Document 1).

JP 2011-25153 A

  However, in the vehicle painting method described in Patent Document 1, since the paints used in the painting process of the automobile body and the bumper are different from each other, it is difficult to match the color tone of the automobile body and the bumper. There is a limit to reducing the color difference between the bumper and the bumper.

  Then, the objective of this invention is providing the coating method which can fully reduce the color difference of the resin member and metal member after coating.

  The present invention [1] includes a step of applying a base coating to a resin member to form a base coating, and a resin clear coating containing a resin additive on the base coating formed on the resin member. Applying and forming a clear coating film for resin, applying a base coating to a metal member, forming a base coating film, and applying a metal clear coating containing a metal additive to the metal member Coating the formed base coating film to form a clear coating film for metal, and the ratio of the average primary particle diameter of the resin additive to the average primary particle diameter of the metal additive Includes a coating method of 0.8 to 1.2.

  According to such a method, the clear paint for resin contains a resin additive suitable for a resin member, and the clear paint for metal contains a metal additive suitable for a metal member.

  However, the resin additive and the metal additive generally have different average primary particle sizes. Therefore, when the clear paint for resin contains the additive for resin and the additive for metal contains the clear paint for metal, the average primary particle size of these additives is different. The clear coating film has a problem that light reflection is different from each other, and the color tone of the resin member and the metal member after coating is different.

  On the other hand, in the above method, since the ratio of the average primary particle diameter of the resin additive to the average primary particle diameter of the metal additive is within the above range, the resin clear paint contains the resin additive, and the metal Even if the additive for use contains a clear paint for metal, the color tone of the resin member and metal member after coating can be matched. As a result, the color difference between the resin member and the metal member after painting can be sufficiently reduced.

  According to the coating method of the present invention, the color difference between the resin member and the metal member after coating can be sufficiently reduced.

FIG. 1 is a schematic configuration diagram showing an example of a vehicle to which an embodiment of a painting method of the present invention is applied. FIG. 2A is a flowchart for explaining one embodiment of a resin member coating process. Drawing 2B is a flow figure for explaining one embodiment of the painting process of a metallic member.

1. As shown in FIG. 1, the vehicle 1 includes a vehicle frame 4 and a sheet metal door 5 as examples of metal members, a fender 2, a front bumper 9, and a rear bumper 3 as examples of resin members. .

  The vehicle frame 4 is formed from a metal steel plate and includes, for example, a roof panel 6, a hood panel 7, a rear fender panel 8, and the like.

  The sheet metal door 5 is formed from a metal steel plate and is attached to the vehicle frame 4. Note that the vehicle 1 includes two sheet metal doors 5 on each side of the vehicle 1.

  The fender 2, the front bumper 9, and the rear bumper 3 are formed from a resin material. The resin material is not particularly limited. For example, polyolefin (for example, polyethylene, polypropylene, etc.), polystyrene, ABS resin, vinyl chloride, polycarbonate, polyacetal, polyester, polyamide, polyurethane, polyphenylene oxide, polymethyl methacrylate, epoxy resin, A phenol resin, a melamine resin, etc. are mentioned. The resin materials can be used alone or in combination of two or more. Among the resin materials, polyolefin is preferable, and polypropylene is more preferable.

  The fender 2 is mounted on the side of the vehicle frame 4 and is disposed adjacent to the front side of the sheet metal door 5. The rear end portion of the fender 2 and the front end portion of the sheet metal door 5 form a vertical dividing line 10 (boundary portion) extending in the vertical direction (vertical direction).

  The front bumper 9 is attached to the front end of the vehicle 1 and is disposed adjacent to the lower side of the front portion of the fender 2. The front bumper 9 extends along the vehicle width direction.

  The rear bumper 3 is attached to the rear end portion of the vehicle 1 and is disposed adjacent to the lower side of the rear fender panel 8. The rear bumper 3 extends along the vehicle width direction. The upper end portion of the rear bumper 3 and the lower end portion of the rear fender panel 8 form a horizontal dividing line 11 (boundary portion) extending in the horizontal direction (lateral direction).

In such a vehicle 1, a resin material (such as a fender 2, a front bumper 9, and a rear bumper 3) is painted on a resin member coating line, and a metal member (such as a vehicle frame 4 and a sheet metal door 5) is separately painted on a metal member. After being painted on the line, the vehicle frame 4 is assembled by assembling the fender 2, the front bumper 9, the rear bumper 3, the sheet metal door 5, and the like.
2. Vehicle Painting One embodiment of the painting method of the present invention is employed for vehicle 1 painting.
(1) Coating method of resin member First, with reference to FIG. 2A, the coating method of resin materials (fender 2, the front bumper 9, the rear bumper 3, etc.) is demonstrated.

The coating method of the resin member includes a base coating step of applying a base paint to the resin member and a clear coating step of applying a clear paint for resin on a base coating film formed on the resin member. Further, such a coating method includes an adjustment process for adjusting the non-volatile content of the base coating film between the base coating process and the clear coating process, and a baking process as a subsequent process of the clear coating process, if necessary. It is out. In such a coating method, the base coating process, the adjustment process, the clear coating process, and the baking process are performed by a flow operation in the resin member coating line.
(1-1) Base coating process In the base coating process, a base coating is applied to a resin member (base coating).

  A primer layer is formed on the resin material, if necessary, by primer treatment using a known method in advance.

  The base paint is an organic solvent-based paint and contains, for example, a base coating film forming component and an organic solvent.

  The base coating film forming component is dissolved or dispersed in an organic solvent. The base coating film forming component contains, for example, a base resin component, a base curing agent, and the like.

  Examples of the base resin component include acrylic resin, polyester resin, alkyd resin, epoxy resin, and polyurethane resin. Among such base resin components, an acrylic resin and a polyester resin are preferable.

  Examples of the acrylic resin include acrylic resins and modified acrylic resins (for example, chlorinated polyolefin-modified acrylic resins, polycaprolactone-modified acrylic resins, urethane-modified acrylic resins, etc.) disclosed in JP-A-61-1161179.

  Examples of the polyester resin include polyester resins and modified polyester resins disclosed in JP-A No. 61-161179 (for example, chlorinated polyolefin-modified polyester resin, polycaprolactone-modified polyester resin, urethane-modified polyester resin, etc.).

  The base resin component can be used alone or in combination of two or more. Among the base resin components, an acrylic resin disclosed in JP-A No. 61-161179 is preferable.

  The base resin component contains a hydroxyl group. The hydroxyl value of the base resin component is, for example, 10 mgKOH / g or more, preferably 30 mgKOH / g or more, for example, 150 mgKOH / g or less, preferably 100 mgKOH / g or less. The hydroxyl value can be measured according to the description of JIS K-1557-1 (2007).

  Further, the number average molecular weight of the base resin component is, for example, 20000 or more, preferably 25000 or more, for example, 60000 or less, preferably 40000 or less. The number average molecular weight is calculated by converting to standard polystyrene by gel permeation chromatography.

  As a base hardening | curing agent, a melamine resin, block polyisocyanate etc. are mentioned, for example, Preferably, a melamine resin is mentioned.

  Examples of the organic solvent include hydrocarbon solvents (for example, xylene and toluene), alcohol solvents (for example, methyl alcohol and isopropyl alcohol), ether alcohol solvents (for example, ethylene glycol, propylene glycol, ethylene glycol monomethyl). Ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, etc.), ketone solvents (eg, methyl isobutyl ketone, cyclohexanone, isophorone, etc.), ester solvents (eg, ethylene glycol monoethyl ether acetate, etc.) It is done. The organic solvent can be used alone or in combination of two or more. Among organic solvents, a hydrocarbon solvent is preferable, and a mixed solvent (thinner) in which a hydrocarbon solvent, an alcohol solvent, and an ester solvent are mixed is more preferable.

  Moreover, the base coating material can contain a metallic pigment (brighting material) and a coloring pigment as needed.

  Examples of metallic pigments include aluminum powder, flaky aluminum oxide, pearl mica, and flaky mica, and preferably flaky aluminum oxide. The metallic pigments can be used alone or in combination of two or more.

  The average value of the maximum length of the metallic pigment (in the case of a spherical shape, the average primary particle diameter) is, for example, 5 μm or more, preferably 10 μm or more, for example, 30 μm or less, preferably 18 μm or less.

  Examples of the color pigment include white pigments (eg, titanium dioxide, zinc oxide), blue pigments (eg, bitumen, ultramarine, cobalt blue, blue copper phthalocyanine), yellow pigments (eg, yellow lead, synthetic yellow iron oxide) , Transparent potato (yellow), bismuth vanadate, titanium yellow, zinc yellow (zinc yellow), etc.), red pigment (eg, red lead, monoazo red, monoazo red, unsubstituted quinacridone red, azo lake (Mn salt), etc.), green Pigments (eg, chromium oxide, chlorinated phthalocyanine green, brominated phthalocyanine green, etc.), orange pigments (eg, pyrazolone orange, benzimidazolone orange, etc.), purple pigments (eg, dioxazine violet, perylene violet, etc.) It is done. The color pigments can be used alone or in combination of two or more. Of the color pigments, blue copper phthalocyanine is preferable.

  The average value of the maximum length of the color pigment (in the case of a spherical shape, the average primary particle diameter) is, for example, 0.05 μm or more, preferably 0.1 μm or more, for example, 0.4 μm or less, preferably 0. .25 μm or less.

  The non-volatile fraction (NV) of such a base paint is less than 35% by mass, preferably 30% by mass or less, for example, 15% by mass or more, preferably 20% by mass or more. The non-volatile fraction (NV) can be measured by (mass after drying ÷ mass before drying) × 100.

  The base coating method is not particularly limited, and examples thereof include an air spray method and an airless spray method, preferably an air spray method, and more specifically, a bell coating method.

  The base paint application method and application conditions are preferably the same as the base paint application method and application conditions for metal members described below. For example, when the base coating method for the metal member described later is the bell coating method, preferably, the base coating method is the bell coating method, and the coating conditions (for example, the diameter of the bell coating machine, the air flow rate, the coating material) The discharge amount, the distance between the bell coating machine and the member, etc.) are also adjusted to be the same.

  Moreover, the temperature in a base coating process is 15 degreeC or more, for example, Preferably, it is 20 degreeC or more, for example, 30 degrees C or less, Preferably, it is 28 degrees C or less.

  By the above, a base coating material is apply | coated on the surface of a resin member (on the surface of a primer layer if needed), and a base coating film is formed.

The thickness of the base coating film before the adjustment step is, for example, 14 μm or more, preferably 21 μm or more, for example, 29 μm or less, preferably 26 μm or less.
(1-2) Adjustment Step Next, preferably, the nonvolatile fraction (NV) of the base coating film on the resin member is adjusted to a predetermined range.

  The method for preparing the non-volatile fraction of the base coating film is not particularly limited as long as the non-volatile fraction can be adjusted to the above range. For example, a method for securing an interval until the clear coating process for a certain period of time (room temperature drying), base coating, Examples include a method of heating and drying the film (preheating), a method of drying the base coating film at room temperature, and then drying by heating (preheating).

  When securing the interval to the clear coating process for a certain time or more, the base coating film is dried at room temperature (for example, 20 to 30 ° C.). In such a case, the drying time (setting time, interval time until clear coating process) is appropriately changed according to the type of organic solvent contained in the base coating film, for example, 3 minutes or more, preferably 5 minutes or more, for example, 20 minutes or less, preferably 15 minutes or less.

  When adjusting the non-volatile fraction of the base coating film only by heating and drying (preheating), the heating temperature is appropriately changed according to the type of organic solvent contained in the base coating film, for example, 40 ° C. or higher, preferably Is 50 ° C. or more, for example, 85 ° C. or less, preferably 80 ° C. or less, and the drying time is, for example, 1 minute or more, preferably 3 minutes or more, for example, 10 minutes or less, preferably 5 minutes or less. It is.

  When adjusting the non-volatile content of the base coating film by drying at room temperature and then drying by heating (preheating), the drying time (setting time) of room temperature drying is, for example, 1 minute or more, preferably 2 minutes or more, for example, 7 minutes. Hereinafter, preferably 5 minutes or less, the heating temperature of the heat drying is in the above range, and the drying time of the heat drying is, for example, 1 minute or more, preferably 2 minutes or more, for example, 10 minutes or less, Preferably, it is 5 minutes or less, more preferably 4 minutes or less.

  Among the methods for preparing the non-volatile fraction of the base coating film, preferably, a method of securing an interval until the clear coating step for a certain time or more, and a method of drying the base coating film at room temperature and then drying by heating. More preferably, a method in which the base coating film is dried at room temperature and then dried by heating is exemplified.

  By the above, the organic solvent in a base coating film volatilizes, the non-volatile fraction (NV) of a base coating film is adjusted, and the viscosity of a base coating film improves.

  The non-volatile fraction (NV) of the base coating film after the adjustment step is, for example, 80% by mass or more, preferably 85% by mass or more and less than 100% by mass, preferably 90% by mass or less, and more preferably 89% by mass. % Or less.

  If the non-volatile fraction of the base coating film is equal to or more than the above lower limit, the viscosity of the base coating film can be improved, and the orientation of the metallic pigment in the base coating film when a clear paint for resin described later is applied. Can be prevented from being disturbed. Moreover, if the non-volatile fraction of a base coating film is below the said upper limit, the time required for adjustment of a non-volatile fraction can be aimed at.

  Also, the difference between the non-volatile fraction of the base coating film after the adjustment process and the non-volatile fraction of the base coating film before the adjustment process (the non-volatile fraction of the base coating film after the adjustment process-the base coating film before the adjustment process The non-volatile fraction is, for example, 12% by mass or more, preferably 15% by mass or more, for example, 20% by mass or less, preferably 19% by mass or less.

The thickness of the base coating film after the adjusting step is, for example, 11 μm or more, preferably 16 μm or more, for example, 21 μm or less, preferably 19 μm or less.
(1-3) Clear coating process Next, the clear coating material for resin is apply | coated to the surface of the base coating film on a resin member (clear coating).

  The clear paint for resin is an organic solvent-based paint and contains, for example, a clear coating film forming component, an additive for resin, and the organic solvent described above.

  The clear coating film forming component is dissolved or dispersed in an organic solvent. The clear coating film-forming component contains, for example, a clear resin component, a clear curing agent, and the like.

  Examples of the clear resin component include the same type of resin as the above base resin component, and specifically, a hydroxyl group-containing resin disclosed in JP-A No. 61-161179. The clear resin component can be used alone or in combination of two or more. Among the clear resin components, an acrylic resin is preferable.

  Moreover, the clear resin component contains a hydroxyl group. The hydroxyl value of the clear resin component is, for example, 100 mgKOH / g or more, preferably 120 mgKOH / g or more, for example, 200 mgKOH / g or less, preferably 180 mgKOH / g or less.

  The number average molecular weight of the clear resin component is, for example, 8000 or more, preferably 10,000 or more, for example, 35000 or less, preferably 25,000 or less. Further, the number average molecular weight of the clear resin component is preferably smaller than the number average molecular weight of the base resin component, specifically, it is preferably 10,000 or more, particularly preferably 15000 or less, than the number average molecular weight of the base resin component. .

  As a clear hardening | curing agent, the polyisocyanate compound disclosed by Unexamined-Japanese-Patent No. 61-161179 is mentioned, for example. Specifically, the polyisocyanate compound is a compound having two or more isocyanate groups in the molecule, and includes tolylene diisocyanate, 4,4-diphenylmethane diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, hydrogenated diphenylmethane diisocyanate, Examples include isophorone diisocyanate and trimethylhexamethylene diisocyanate. Moreover, these multimers and a trimethylol propane adduct body are mentioned. Clear curing agents can be used alone or in combination of two or more. Among the clear curing agents, a hexamethylene diisocyanate multimer is preferable.

  The mixing ratio of the clear resin component and the clear curing agent is not particularly limited, but the clear curing agent has an NCO / OH (equivalent ratio) of, for example, 0.5 or more, preferably 0, with respect to the clear resin component. 7 or more, more preferably more than 1.0, for example, 2.5 or less, preferably 2.0 or less.

  The resin additive is contained in the resin clear paint in order to ensure various performances required for the resin clear paint.

  Examples of the resin additive include a rheology control agent (RC agent), a UV absorber, a surface conditioner, and an antifoaming agent. The resin additives can be used alone or in combination of two or more. Of the additives for resin, an RC agent is preferable.

  Examples of the RC agent include fumed silica, urea aggregate, and microgel. The RC agent can be used alone or in combination of two or more. Among the RC agents, fumed silica is preferable.

  The average primary particle diameter of the resin additive is, for example, 0.1 μm or more, preferably 0.2 μm or more, for example, 2 μm or less, preferably 1 μm or less, more preferably 0.9 μm or less, and particularly preferably 0.3 μm or less.

  The ratio of the average primary particle diameter of the resin additive to the average primary particle diameter of the metal additive described later (average primary particle diameter of the resin additive / average primary particle diameter of the metal additive) is 0.8. As mentioned above, Preferably, it is 0.9 or more and 1.2 or less, Preferably, it is 1.0 or less.

  If the average primary particle size of the additive for resin / average primary particle size of the additive for metal is within the above range, it is possible to suppress the difference in reflection of light in the clear coating film for resin and the clear coating film for metal, The color difference between the painted metal member and resin member can be sufficiently reduced.

  The content ratio of the resin additive is, for example, 3% by mass or more, preferably 5% by mass or more, for example, 15% by mass or less, preferably 10% by mass with respect to the total nonvolatile content of the resin clear paint. % Or less.

  The non-volatile fraction of such a clear paint for resin is, for example, 45 mass% or more, preferably 47 mass% or more, for example, 55 mass% or less, preferably 53 mass% or less.

  Examples of the method for applying the clear paint for resin include the same methods as those for applying the base paint. The coating method and coating conditions of the clear resin coating are preferably the same as the coating method and coating conditions of the metal clear coating described below. For example, when the metal clear coating method described later is a bell coating method, preferably, the resin clear coating method is a bell coating method, and coating conditions (for example, the diameter of the bell coating machine, the air flow rate, The amount of paint discharged, the distance between the bell coater and the member, etc.) are also adjusted to be the same.

  Moreover, the temperature in a clear coating process is 18 degreeC or more, for example, Preferably, it is 20 degreeC or more, for example, 30 degrees C or less, Preferably, it is 28 degrees C or less.

  As described above, the resin clear coating is applied on the surface of the base coating to form a resin clear coating. At this time, part of the clear curing agent in the clear coating film for resin penetrates into the base coating film.

The thickness of the clear coating film for resin before the baking step is, for example, 25 μm or more, preferably 30 μm or more, for example, 50 μm or less, preferably 45 μm or less.
(1-4) Baking process Next, the base coating film and the clear coating film for resin are baked. Examples of the baking method include hot air heating, infrared heating, and high frequency heating. The baking temperature is, for example, 80 ° C. or higher, preferably 90 ° C. or higher, for example, 120 ° C. or lower, preferably 110 ° C. or lower. The baking time is, for example, 20 minutes or more, preferably 25 minutes or more, for example, 40 minutes or less, preferably 35 minutes or less.

Thus, the base coating film and the clear coating film for resin are baked and cured. In this way, the resin member is painted.
(2) Method for Painting Metal Member Next, a method for painting a metal member (such as the vehicle frame 4 and the sheet metal door 5) will be described with reference to FIG. 2B. The metal member coating method is performed by a flow operation in a metal member coating line.
(2-1) Base coating process In the metal member coating method, a base paint is applied to the metal member by the above-described coating method (base coating).

  On the metal member, an undercoat layer is formed by electrodeposition coating (undercoating) by a known method in advance, and an intermediate coating layer is formed by an intermediate coating treatment.

  Examples of the base paint applied to the metal member include paints similar to the base paint applied to the resin member. The base paints may be different but are preferably the same. That is, the base coating applied to the metal member preferably contains a base coating film forming component and an organic solvent, and optionally contains a metallic pigment and a coloring pigment.

  As described above, the base paint is applied on the surface of the metal member (on the surface of the intermediate coating layer) to form a base coating film. The base coating film on the metal member is preferably the same as the base coating film on the resin member.

The thickness of the base coating film before the clear coating step is, for example, 11 μm or more, preferably 16 μm or more, for example, 21 μm or less, preferably 19 μm or less.
(2-2) Clear painting process Next, the metal clear coating is apply | coated to the surface of the base coating film formed in a metal member (clear coating for metals).

  The metal clear coating is a coating that cures at a relatively high baking temperature (preferably 120 ° C. or higher and 160 ° C. or lower) described later, and has a relatively low baking temperature (preferably 90 ° C. or higher and 110 ° C. or lower). It is different from clear paint for resin that hardens at. The metal clear paint is an organic solvent-based paint, and includes, for example, the above base coating film forming component, the metal additive, and the above organic solvent.

  The metal additive is contained in the metal clear paint in order to ensure various performances required for the metal clear paint.

  Examples of the metal additive include the above RC agent, UV absorber, surface conditioner, antifoaming agent and the like. Metal additives can be used alone or in combination of two or more. Among metal additives, an RC agent is preferable.

  The average primary particle size of the metal additive is, for example, 0.1 μm or more, preferably 0.2 μm or more, for example, 2 μm or less, preferably 1 μm or less.

  The difference between the average primary particle size of the metal additive and the average primary particle size of the resin additive is, for example, ± 0.2 μm or less, preferably ± 0.1 μm or less, more preferably ± 0.05 μm. It is as follows.

  Further, the content of the metal additive is, for example, 3% by mass or more, preferably 5% by mass or more, for example, 10% by mass or less, preferably 8% by mass with respect to the total nonvolatile content of the metal clear paint. % Or less.

  The non-volatile fraction of such a metal clear paint is, for example, 45% by mass or more, preferably 47% by mass or more, for example, 55% by mass or less, preferably 53% by mass or less.

  Examples of the method for applying the metal clear paint include the same methods as those for the base paint.

  As described above, the metal clear coating is applied on the surface of the base coating film formed on the metal member, and the metal clear coating film is formed.

The thickness of the clear coating film for metal before the baking step is, for example, 25 μm or more, preferably 30 μm or more, for example, 50 μm or less, preferably 45 μm or less.
(2-3) Baking process Next, the base coating film and the clear coating film for metal are baked by the above baking method. The baking temperature is, for example, 120 ° C. or higher, preferably 130 ° C. or higher, for example, 170 ° C. or lower, preferably 160 ° C. or lower. The baking time is, for example, 20 minutes or more, preferably 25 minutes or more, for example, 40 minutes or less, preferably 35 minutes or less.

As described above, the base coating film and the clear coating film for metal are baked and cured. In this way, the metal member is painted.
(3) Vehicle Assembly Step Thereafter, as shown in FIG. 1, the painted resin member is assembled to the painted metal member to assemble the vehicle 1.
3. In such a coating method, the resin clear paint contains the resin additive, the metal clear paint contains the metal additive, and the resin additive with respect to the average primary particle size of the metal additive. The ratio of the average primary particle diameter is 0.8 or more and 1.2 or less.
Therefore, it can suppress that light reflection etc. differ in the clear coating film for resin, and the clear coating film for metals, and can fully reduce the color difference of the resin member and metal member after coating.

  As shown in FIG. 1, the sheet metal door 5 and the fender 2 are arranged so as to form a vertical dividing line 10 that is adjacent to the front-rear direction and extends in the vertical direction (vertical direction). In such a case, the sheet metal door 5 and the fender are more scientifically compared with the case where the rear fender panel 8 and the rear bumper 3 are arranged so as to form a horizontal dividing line 11 extending in the horizontal direction (horizontal direction). It is easy to feel the color difference from 2.

However, according to the above-described coating method, the color difference between the painted metal member and the resin member can be sufficiently reduced. Therefore, even if the metal member and the resin member are arranged so as to form a vertical dividing line, the metal member and the resin The color tone with the member can be matched.
4). In the above embodiment, the resin member coating method includes the adjustment step of adjusting the non-volatile fraction of the base coating film between the base coating step and the clear coating step, but is not limited thereto. Said coating method does not need to include an adjustment process.

  Preparation Examples and Examples are shown below to further illustrate the present invention, but the present invention is not limited to them. Specific numerical values such as blending ratio (content ratio), physical property values, and parameters used in the following description are described in the above-mentioned “Mode for Carrying Out the Invention”, and the corresponding blending ratio (content ratio) ), Physical property values, parameters, etc. The upper limit value (numerical value defined as “less than” or “less than”) or lower limit value (number defined as “greater than” or “exceeded”) may be substituted. it can.

Examples 1-3
-Resin member coating process The base paint shown below was applied to the fender 2 and rear bumper 3 (resin member) that had been previously primed by the bell coating (base coating) to form a base coating film (base coating process) ).

Base paint: Trade name Base paint A (manufactured by Kansai Paint), composition [acrylic resin (base resin component, hydroxyl value 65 mgKOH / g, number average molecular weight 32500), melamine resin (base curing agent), flaky aluminum oxide (metallic) Pigment), thinner (organic solvent)], non-volatile fraction (before application) 25% by mass
Next, the base coating film was dried at room temperature and then dried by heating (preheating) under the conditions shown in Table 1 (adjustment step). Table 1 shows the nonvolatile fraction of the base coating film after the adjustment step.

  Next, a clear coating for resin (curing temperature of 100 ° C. or less) shown below was applied to the surface of the base coating by bell coating (clear coating) to form a clear coating for resin (clear coating process).

Clear paint for resin: trade name Clear paint A (manufactured by Kansai Paint), composition [acrylic resin (clear resin component, hydroxyl value 150 mgKOH / g, number average molecular weight 17500), clear curing agent A (clear curing agent), fumed Silica (rheology control agent, average primary particle size 0.1 μm, content of 5% by mass of non-volatile content of clear paint for resin, thinner (organic solvent)], non-volatile content (before application) 50% by mass
Next, the base coating film and the clear coating film for resin were baked at a baking temperature of 100 ° C. for a baking time of 30 minutes.

As described above, the base coating film and the resin clear coating film laminated on the surfaces of the fender 2 and the rear bumper 3 (surface of the primer layer) were cured, and the fender 2 and the rear bumper 3 were painted.
・ Coating process for metal parts The vehicle base 4 and sheet metal door 5 (metal parts), which have been previously electrodeposited and intermediate coated, are painted with the same paint as the above base paint (base paint) by bell painting. A coating film was formed (base coating process).

  Next, the metal clear paint (curing temperature 120 ° C. or more and 140 ° C. or less) shown below was applied to the surface of the base coating by bell coating (clear coating) to form a metal clear coating (clear coating process) ).

Clear paint for metals: trade name Clear paint B (manufactured by Kansai Paint Co., Ltd.), composition [acrylic resin (base resin component, hydroxyl value 150 mgKOH / g, number average molecular weight 17500), melamine resin (base curing agent), fumed silica ( Rheology control agent, average primary particle size 0.1 μm, content ratio 5% by mass of the non-volatile content of the metal clear paint), thinner (organic solvent)], non-volatile content (before application) 50% by mass
Next, the base coating film and the clear coating film for metal were baked at a baking temperature of 140 ° C. and a baking time of 30 minutes.

  As described above, the base coating film and the metal clear coating film laminated on the surfaces of the vehicle frame 4 and the sheet metal door 5 (surface of the intermediate coating layer) were cured, and the vehicle frame 4 and the sheet metal door 5 were painted.

Example 4
In the adjustment step, the fender 2 and the rear bumper 3 were applied in the same manner as in Example 1 except that the nonvolatile fraction of the base coating film was adjusted only by room temperature drying (no preheating). The room temperature drying time (setting time) is shown in Table 1.

Example 5
Fender 2 and rear bumper 3 were applied in the same manner as in Example 1 except that the base paint further contained blue copper phthalocyanine (blue pigment).

Example 6
Fender 2 and rear bumper 3 were applied in the same manner as in Example 4 except that the base paint further contained blue copper phthalocyanine (blue pigment).

Comparative Examples 1 and 2
Fender 2 and rear bumper 3 were applied in the same manner as in Example 1 except that the average primary particle size of the rheology control agent (RC agent) of the clear paint for resin was changed as shown in Table 1.
<Evaluation of turbidity and yellowness of clear coating film for resin>
The turbidity of the clear coating film for resin in the fender 2 and the rear bumper 3 coated in each example and comparative example was visually evaluated according to the following criteria.
○: No color difference is confirmed.
X: A color difference is confirmed.

The yellowness of the clear coating film for resin in the fender 2 and the rear bumper 3 coated in each example and comparative example was visually evaluated according to the following criteria.
○: No color difference is confirmed.
X: A color difference is confirmed.
<Evaluation of color difference between resin member and metal member>
As shown in FIG. 1, the fender 2 and the rear bumper 3 painted in each example and comparative example, and the sheet metal door 5 painted in each example are assembled to the vehicle frame 4 painted in each example. The vehicle 1 was assembled.

  The color difference between the resin member (fender 2 and rear bumper 3) and the metal member (vehicle frame 4 and sheet metal door 5) was visually evaluated according to the following criteria. The results are shown in Table 1.

  A: No color difference was confirmed between the fender 2 forming the vertical dividing line 10 and the sheet metal door 5, and no color difference was confirmed between the rear bumper 3 forming the horizontal dividing line 11 and the rear fender panel 8.

  B: Although a slight color difference was confirmed between the fender 2 and the sheet metal door 5, no color difference was confirmed between the rear bumper 3 and the rear fender panel 8.

  C: A slight color difference was confirmed between the fender 2 and the sheet metal door 5, and a slight color difference was confirmed between the rear bumper 3 and the rear fender panel 8.

1 Vehicle 2 Fender 3 Rear Bumper 4 Vehicle Frame 5 Sheet Metal Door

Claims (1)

Applying a base paint to a resin member to form a base coating film;
Applying a clear paint for resin containing an additive for resin on the base coating film formed on the resin member to form a clear coating film for resin;
Applying a base paint to a metal member to form a base coating film;
Applying a metal clear paint containing a metal additive on the base coating film formed on the metal member to form a metal clear coating film,
The ratio of the average primary particle diameter of the said resin additive with respect to the average primary particle diameter of the said metal additive is 0.8 or more and 1.2 or less, The coating method characterized by the above-mentioned.

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