JP5515362B2 - How to paint a car body - Google Patents

Description

The present invention relates to paint how the automobile body to be coated by applying a coating material to the outer plate surface and the inner plate surface of the automobile body undercoating film is formed.

  Conventionally, as shown in Patent Document 1 below, chipping resistance and smoothness of a multi-layer top coating film formed by sequentially applying a first colored top coating, a second colored top coating, and a clear coating to be formed on an electrodeposition coating surface For the purpose of improving the property, an automobile outer plate portion or the like that forms a multi-layer top coat film by sequentially applying a first colored top coat paint, a second colored top coat paint and a clear paint on the cationic electrodeposition coated surface, etc. In the method for coating a conductive metal product, the first colored top coating composition comprises, as a resin component, (1) a mixture comprising a hydroxyl group-containing resin and a melamine resin, or (2) a carboxyl group-containing resin and an epoxy group-containing resin. There is known a mixture using a colored paint containing a flake pigment at a ratio of 0.5 parts by weight or more per 100 parts by weight of resin solids.

JP 2000-281963 A

  As described above, the first colored top coating, the second colored top coating, and the clear coating are sequentially applied to the cationic electrodeposition coating surface, and then cured simultaneously to form a multi-layer top coating film. In the method for forming a layer coating film, by adding a specific amount of flake pigment to the first colored top coating material, the smoothness and anti-resistance property of the coating film can be eliminated even if the conventional intermediate coating method or the drying step is omitted. Chipping property can be improved. However, if the coating of the intermediate coating is omitted as described above, the ultraviolet blocking function and the like that the intermediate coating has had cannot be obtained. For this reason, when the top coat is a paint having a weak UV blocking function, such as a blue, white or red paint, an ultraviolet ray is applied to the undercoat made of an electrodeposition paint formed on the outer surface of the vehicle body. However, it is unavoidable that the undercoating film is easily deteriorated at an early stage.

  In order to prevent the above-mentioned adverse effects, it is conceivable to conceal and protect the undercoat by mixing a pigment having a function of reflecting or diffusing ultraviolet rays or the like into the first colored top coat. In this case, the pigment mixed in the first colored top coat may adversely affect the paint applied on the inner plate surface of the vehicle body. That is, since the coating film made of the second colored top coating applied on the outer surface of the vehicle body develops the color of the exterior coating film of the vehicle body, it is selected from a wide variety of colors used in advance. In addition, the coating film made of the top coating applied on the inner plate surface may be the same color or approximate color as the coating made of the second colored top coating applied on the outer plate surface from the viewpoint of aesthetics. It is common. On the other hand, if the first colored top coating applied below the coating formed by the second colored top coating is a coating film of the upper layer capable of developing a desired appearance coating color, The color can be an achromatic color, and thus the first colored top coat can be made versatile. However, in such a configuration, when the first colored top coat is applied on the outer plate surface of the vehicle body, if the dust adheres to the upper coat film on the inner plate surface, the aesthetics on the inner plate surface is improved. There is a problem of lowering.

  In addition, the color of the coating film formed by the first colored top coating material, the coating film composed of the second colored top coating material constituting the appearance coating color and the coating film composed of the third coating material applied to the inner plate surface When the same color or approximate color is used, even if the dust of the first colored top coating material adheres to the top coating film of the inner plate surface, the aesthetic appearance of the coating film on the inner plate surface is not significantly reduced. . However, in order to set the coating film made of the first colored top coating material mixed with the pigment having the background concealing property as described above to various colors corresponding to the appearance coating film color, It is inevitable that the workability of painting is deteriorated because it is necessary to prepare a large number of pipes required for painting the colored top coat and frequently replace them.

The present invention has been made in view of the above problems, and is caused by the fact that the dust of the paint applied on the outer plate surface of the automobile body with a simple configuration adheres to the coating film on the inner plate surface. it is intended to provide a coating how the automobile body can be prevented from lowering of the aesthetic effectively.

The invention according to claim 1 is a first coating film forming step of forming a first coating film for coloring the appearance coating film color by applying the first coating material on the inner plate surface of the automobile body on which the base coating film is formed. And a second coating film forming step of forming a second coating film having a base concealing property by applying a second coating material on the outer plate surface of the automobile body, and after forming the second coating film, Applying three paints, the underlying coating is less concealed than the second coating film, and the third coating film alone or together with the second coating film has the same or similar appearance coating color as the first coating film. And a third coating film forming step for forming a third coating film , wherein the vehicle body and the electrostatic coating machine are charged to opposite electrodes in the second coating film forming step. The second paint can be sprayed on the outer plate surface of the car body, and the sprayed second paint can go around the inner plate surface. In places where there is a gender, by controlling the potential applied to the inner plate surface of the automobile body, so as to apply a second coating material to the outer plate surface while suppressing the said second coating material from flowing in the inner plate face It is a thing.

  Here, the base concealing property means that the transmittance of ultraviolet light (300 to 400 nm) is 0.05% or less and the black and white concealing property in the case of a coating color with a lightness ≦ 60 (illumination angle −45 °, light receiving angle 0 °). Can be ensured at 10 μm or less, and the transmittance of ultraviolet light (300 to 400 nm) is 0.05% or less when the coating color (lighting angle −45 °, light receiving angle 0 °) with lightness> 60 is black and white. This means that the concealability can be secured at 20 μm or less (see JIS K 5400 · 7.2 (2) f).

  The approximate color means a color difference ≦ 2 (illumination angle −45 °, light receiving angle 0 °) (see JIS Z 8730).

According to a second aspect of the present invention, in the method for coating an automobile body according to the first aspect , in the second coating film forming step, the second coating film having a lightness lower than that of the third coating film is formed on the outer plate surface. To form.

The invention according to claim 3 is the inner plate clear coating film for forming the clear coating film on the inner plate surface at least after the first coating film forming step in the automobile body coating method according to claim 1 or 2. A forming step is provided.

The invention according to claim 4 is the automobile body coating method according to any one of claims 1 to 3 , wherein a clear coating film is formed on the outer plate surface at least after the third coating film forming step. An outer plate clear coating film forming step is provided.

According to the first aspect of the present invention, when the second coating material is applied to the outer plate surface of the automobile body in the second coating film forming step, the second coating material is prevented from turning around to the inner plate surface side. since you can effectively prevent deterioration of appearance due to the second paint dust adheres to the inner plate surface. Moreover, since the second paint can be made versatile by setting the color of the second coating film formed by the second paint to an achromatic color, etc., piping necessary for applying the second paint is provided. The aesthetics caused by the fact that the dust of the second paint applied on the outer plate surface of the automobile body adheres to the first coating film on the inner plate surface while effectively simplifying the coating apparatus. By effectively preventing a decrease, and by mixing a pigment for concealing the base into the second paint forming the second coating film, or by setting the content of the color pigment in the second paint more than usual. The base hiding property of the second coating film can be effectively improved. Therefore, the visible light or ultraviolet rays irradiated on the outer plate surface are simplified while omitting the operation of applying the intermediate coating on the base coating film formed on the outer plate surface and drying it, thereby simplifying the painting process. Etc. can be reflected or absorbed by the carbon black or coloring pigment blended in the second coating film, and ultraviolet rays etc. can be prevented from reaching the base coating film. There is an advantage that it can be effectively prevented. In particular, in the second coating film forming step, the automobile body and the electrostatic coating machine are charged to the opposite electrodes to spray the second paint on the outer plate surface of the automobile body, and the sprayed second paint is In the place where there is a possibility of going around to the inner plate surface side, by suppressing the potential applied to the inner plate surface of the car body, the second paint is prevented from going around the inner plate surface side, There exists an advantage that the fall of the beauty | look by the dust of the said 2nd coating material adhering to an inner-plate surface with a simple structure can be prevented effectively.

In the invention which concerns on Claim 2 , the brightness of the 2nd coating film formed in the outer-plate surface of a motor vehicle body in a 2nd coating-film formation process by setting more content of the color pigment with respect to a 2nd coating than usual etc. However, because it is configured to be lower than the third coating film formed on the outer plate surface of the automobile body in the third coating film forming step, it is caused by the fact that the base coating film is irradiated with ultraviolet rays with a simpler configuration, etc. There is an advantage that early deterioration of the applied undercoat can be effectively suppressed.

In the invention which concerns on Claim 3, since it comprised so that a clear coating film might be formed on the said 1st coating film formed on the inner-plate surface, the said 1st coating film is protected by this clear coating film, and the There is an advantage that weather resistance and smoothness can be effectively maintained.

In the invention according to claim 4, the car bodies of the outer plate surface on which is formed in the upper third coating film, which is adapted to form a clear coating film protects the third paint film The clear paint film The weather resistance and smoothness can be effectively maintained, and even when the dust of the clear paint sprayed toward the inner plate surface adheres to the third coating film on the outer plate surface, The smoothness of the plate surface can be sufficiently secured.

It is process drawing which shows 1st Embodiment of the coating method of the motor vehicle body which concerns on this invention. It is explanatory drawing which shows the formation process of a 2nd coating film. It is explanatory drawing which shows the coating-film shape formed by the comparison of this invention. It is explanatory drawing which shows the reflective state of the light of the coating film formed by the coating method which concerns on this invention. FIG. 3 is a view corresponding to FIG. 2 showing a third embodiment of the method for painting an automobile body according to the present invention.

  FIG. 1 is a painting process diagram showing a first embodiment of a method and apparatus for painting an automobile body 1 according to the present invention. This coating process includes a base coating film forming process K0 for forming the base coating film 4 on the outer plate surface 2 and the inner plate surface 3 of the automobile body 1, and a first coating on the base coating film 4 on the inner plate surface 3, respectively. First coating film forming step K1 for forming film 5, second coating film forming step K2 for forming second coating film 6 on base coating film 4 on outer plate surface 2, and second coating on outer plate surface 2 A third coating film forming step K3 for forming a third coating film 7 on the film 6, a preheating step K4 for pre-drying the first to third coating films 5 to 7, and a first coating of the inner plate surface 3; An inner plate clear coating film forming step K5 for forming a clear coating film 8 on the film 5, and an outer plate clear coating film forming step K6 for forming a clear coating film 9 on the third coating film 7 on the outer plate surface 2; And a baking drying step K7 for baking and drying the first to third coating films 5 to 7 and the clear coating films 8 and 9 at the same time.

  In the base coating film forming step K0, for example, the automobile body 1 is pulled up from the tank after being applied with a direct current by applying a direct current in a state where the automobile body 1 is immersed in a tank containing an electrodeposition paint. Is transferred into a drying furnace and baked and dried to form a base coating film 4 having an antirust function of the automobile body 1. The electrodeposition coating method includes an anion form using chromate or the like as a rust preventive material and a cation form using a modified epoxy resin or the like excellent in rust preventive power with an amine.

  In the first coating film forming step K1, in the first coating film forming section 12 having the electrostatic coating machine 11 or the like, the outside of the automobile body 1 is opened with the opening / closing body 13 composed of a side door or the like of the automobile being largely opened. By spray-coating the first paint on the plate surface 2, the first coating film 5 that develops the appearance paint film color is formed on the base coating film 4 on the inner plate surface 3. The first paint is a water-soluble paint obtained by dissolving or dispersing a coloring pigment for coloring the appearance paint film color of the inner plate surface 3 and a resin component in a solvent made of water. Depending on the conditions, extender pigments, anti-settling agents, coating surface conditioners, UV absorbers, UV stabilizers, adhesion-imparting agents and the like can be appropriately contained.

  The spray coating of the first paint using the electrostatic coating machine 11 is performed using, for example, an object to be coated made of an automobile body 1 as an anode (+) and an electrostatic coating machine 11 as a cathode (−). In a state where a high voltage of several tens of kV is applied to form a static electric field, the paint particles are charged on the cathode (−) and sprayed, whereby the paint particles are coated with electrostatic attraction (automobile body 1). It is made to adsorb to.

  The color pigment contained in the first paint is a specific color selected from a number of preset appearance paint colors, that is, contained in the following third paint that forms the third paint film 7 on the outer plate surface 2. By using the same ones as those described above, the first coating film 5 is colored in the appearance coating film color set to the same color as the third coating film 7 or an approximate color. Specifically, the color pigments include titanium oxide, zinc white, carbon black, cadmium red, molybdenum red, chromium yellow, chromium oxide, Prussian blue, cobalt blue, azo pigment, phthalocyanine pigment, quinacridone pigment, isoindoline. One kind selected from colored pigments such as a pigment, a selenium pigment, and a perylene pigment can be used, or two or more kinds can be mixed and used.

  As the resin component, it is preferable to use a thermosetting resin composition. Examples of the thermosetting resin composition include a base resin such as an acrylic resin, a polyester resin, and an alkyd resin having a crosslinkable functional group, a melamine resin, a urea resin, a polyisocyanate compound (including a block body), and the like. Examples thereof include a composition comprising a crosslinking agent, an acid / epoxy crosslinked resin composition comprising an acid group-containing resin and an epoxy group-containing resin as main components. In addition, as the resin component, a thermosetting resin having a crosslinkable functional group such as a hydroxyl group, a carboxyl group, and an epoxy group, and a base resin such as an acrylic resin, a polyester resin, and an alkyd resin, and a crosslinking agent such as a melamine resin. More preferably, the composition is used.

  Thereafter, in the second coating film forming step K2, in the second coating film forming section 15 having the electrostatic coating machine 14 or the like, the opening / closing body 13 composed of the side door or the like in the open state is displaced to a substantially closed state. Thereafter, the second coating film 6 having a high base concealing property is applied on the base coating film 4 on the outer panel surface 2 by spraying the second coating material onto the outer panel surface 2 of the automobile body 1 to cause electrostatic adsorption. Form. The second paint forms a first coating film 5 having a base concealing property, and dissolves a pigment for coloring the first coating film 5 into a predetermined color, a resin component, and the like in a solvent made of water. Or it is a water-soluble paint obtained by making it disperse | distribute, and can contain an extender, an anti-settling agent, a coating surface regulator, a ultraviolet absorber, a ultraviolet stabilizer, an adhesion imparting agent, etc. as needed.

  Examples of the pigment contained in the second paint include those selected from the group consisting of carbon black, titanium oxide, iron oxide, aluminum flakes, and combinations thereof. In addition, if necessary, predetermined colored pigments, that is, zinc white, cadmium red, molybdenum red, chrome yellow, chromium oxide, Prussian blue, cobalt blue, azo pigment, phthalocyanine pigment, quinacridone pigment, isoindoline pigment One kind selected from colored pigments such as selenium pigments and perylene pigments may be used, or two or more kinds may be mixed and used.

  As the resin component contained in the second paint, it is preferable to use a thermosetting resin composition as in the first paint. Examples of the thermosetting resin composition include a base resin such as an acrylic resin, a polyester resin, and an alkyd resin having a crosslinkable functional group, a melamine resin, a urea resin, a polyisocyanate compound (including a block body), and the like. Examples thereof include a composition comprising a crosslinking agent, an acid / epoxy crosslinked resin composition comprising an acid group-containing resin and an epoxy group-containing resin as main components. In addition, as the resin component, a thermosetting resin having a crosslinkable functional group such as a hydroxyl group, a carboxyl group, and an epoxy group, and a base resin such as an acrylic resin, a polyester resin, and an alkyd resin, and a crosslinking agent such as a melamine resin. More preferably, the composition is used.

  As the pigment contained in the second paint, for example, a gray-colored pigment made of carbon black, titanium dioxide, or the like was used, thereby corresponding to the third paint film 7 formed on the second paint film 6. The color of the 2nd coating film 6 formed with the said 2nd coating material is set to the achromatic color which has brightness. That is, the color of the second coating film 6 is set to an achromatic color having, for example, five levels of brightness composed of dark gray, gray, ride gray, super light gray, and white and having an excellent background hiding function. It has become. When the content of the color pigment is set higher than usual, that is, when the content of the color pigment is set so that the brightness of the second coating film 6 is lower than the brightness corresponding to the third coating film 7. Therefore, it is possible to sufficiently ensure the base concealing property of the second coating film 6 with a simple configuration.

  In the spray coating of the second paint using the electrostatic coating machine 14, as in the case of the first coating, for example, an object to be coated made of the automobile body 1 is used as an anode (+) and the electrostatic coating machine 14 is used. In the state where a high voltage of several tens of kV is applied between the two and a static electric field is formed between the two, the coating particles are electrostatically charged by spraying the coating particles on the cathode (−). It is carried out by attracting the object to be coated (automobile body 1) by attractive force.

  And the location where the 2nd coating material sprayed from the said electrostatic coating machine 14 may go around to the inner-plate surface 3 side, for example, the vicinity of the opening part 2a formed in the outer-plate surface 2 as shown in FIG. Then, by providing a potential control means 22 for controlling the potential difference between the particles 21 of the second paint and the outer plate surface 2 of the automobile body 1 to be larger than when spraying the second paint on other portions, etc. It is comprised so that the particle | grains 21 of the said 2nd coating material may suppress turning around to the inner-plate surface side. Specifically, when the spray gun 14a of the electrostatic coating machine 14 reaches the vicinity of the opening 2a, the positive potential applied to the outer plate surface 2 through the potential control means 22 is increased, or FIG. Control is performed so as to increase the negative potential applied to the spray gun 14a via an external potential control means. As a result, the second paint sprayed from the electrostatic coating machine 14 is positively adsorbed to the outer plate surface 2, so that it is suppressed from going around to the inner plate surface side through the opening 2 a.

  Note that when the potential difference between the second paint and the outer plate surface 2 of the automobile body 1 is increased as described above, a spark is likely to occur between the spray gun 14 a and the outer plate surface 2. Alternatively, when the electric charges concentrate on the corner portion of the outer plate surface 2, the coating film in that portion tends to be thick locally and the appearance tends to deteriorate. For this reason, it is desirable to suppress the generation of the spark by attaching a device for removing free ions generated during the electrostatic coating, that is, ions that do not contribute to the charged ions of the paint particles. In addition, by properly controlling the spraying pressure of the paint by the spray gun 14a or by sufficiently securing the ground of the outer plate surface 2, it is possible to prevent electric charges from concentrating on the edge portion of the outer plate surface 2. It is desirable to suppress that part of the coating from becoming thick locally.

  Thereafter, in the third coating film forming step K3, in the third coating film forming section 17 having the electrostatic coating machine 16 and the like, while maintaining the opening / closing body 13 composed of the side door or the like in a substantially closed state, the outer plate surface The third coating film 7 is formed by spray-coating the third coating material on the second coating film 6 in an uncured state without curing the second coating film 2. The third paint comprises a coloring pigment for causing the third paint film 7 to have a predetermined appearance paint color, together with the second paint film 7 alone or together with the second paint film 7, a resin component, etc. Alternatively, it is a liquid paint obtained by dissolving or dispersing in a solvent comprising water, and optionally contains extender pigments, anti-settling agents, coating surface conditioners, UV absorbers, UV stabilizers, adhesion promoters, etc. Can be made.

  As the color pigment contained in the third paint, the second paint film has a lower background concealing property than the second paint film 6 and a specific color selected from a number of preset paint film colors. Those that develop color 6 are used. Specifically, the color pigments include titanium oxide, zinc white, carbon black, cadmium red, molybdenum red, chromium yellow, chromium oxide, Prussian blue, cobalt blue, azo pigment, phthalocyanine pigment, quinacridone pigment, isoindoline. One kind selected from colored pigments such as a pigment, a selenium pigment, and a perylene pigment can be used, or two or more kinds can be mixed and used.

  In the preheating step K4 performed after the first to third coating film forming steps K1 to K3 are finished, the vehicle body 1 conveyed to the preheating portion 23 is blown with hot air and irradiated with infrared rays, or a combination thereof is used for the vehicle body. By heating the outer plate surface 2 and the inner plate surface 3, the water in the first to third paints is evaporated, and the first to third coating films 5 to 7 are simultaneously brought into a semi-cured state.

  Thereafter, the process proceeds to the inner plate clear coating film forming step K5 to open the opening / closing body 13, and then the clear coating material is applied to the first coating film 5 on the inner plate surface 3 by air spray, airless spray, static It is applied by an inner plate clear coating film forming unit 24 equipped with a spray coating machine such as an electric system to form a clear coating film 8. As the clear coating film, for example, a solvent-type paint containing a thermosetting resin composition and a solvent is used, and if necessary, a bright pigment, a coloring pigment, an anti-settling agent, a coating surface conditioner, An ultraviolet absorber, an ultraviolet stabilizer, an adhesion-imparting agent, and the like can be appropriately contained. The glitter pigment and the color pigment are preferably blended to such an extent that the transparency of the clear coating film 8 is not impaired.

  Next, the process proceeds to the outer plate clear coating film forming step K6, and after the open / closed opening body 13 is displaced to the substantially closed state, the third coating of the outer plate surface 2 is performed in the same manner as the inner plate clear coating film forming step K5. On the film 7, a clear coating film coating made of a solvent-type coating is applied by an outer plate clear coating film forming unit 25 equipped with a spray coating machine such as an air spray, an airless spray, an electrostatic method, etc. After forming 9, the automobile body 1 is heated at a temperature of about 140 ° C. for about 30 minutes in the baking and drying step K7 to simultaneously cure the coating films.

  A first coating film forming step of forming a first coating film 5 for coloring the appearance coating film color by applying the first coating material on the inner plate surface 3 of the automobile body 1 on which the base coating film 4 is formed as described above. K1, a second coating film forming step K2 for applying a second coating material on the outer plate surface 2 of the automobile body 1 to form a second coating film 6 having a base concealing property, and the second coating film 6 After the formation, a third paint is applied on the base film so as to have a lower background concealing property than the second coating film, and the same color as the first coating film or the same color as the first coating film or the same color as the first coating film. In a coating method and apparatus for an automobile body comprising a third coating film forming step K3 for forming a third coating film 7 for coloring the appearance coating film color, the second coating material is contained in the second coating film forming step K2. Since the second paint is applied to the outer plate surface 2 while suppressing the wraparound to the plate surface 3 side, General-purpose for the second paint while easily and effectively preventing the deterioration of the aesthetics caused by the dust of the second paint applied on the surface 2 adhering to the first coating 5 on the inner plate surface 3 Therefore, there is an advantage that the equipment cost can be reduced and the labor of painting can be effectively simplified.

  That is, after the completion of the first coating film forming step K1 for forming the first coating film 5 on the inner plate surface 3 of the automobile body 1 as described above, the second and third portions are formed on the outer plate surface 2 of the automobile body 1. When the second and third coating film forming steps K2 and K3 for forming the coating films 6 and 7 are provided, the third coating film 7 formed on the outer plate surface 2 of the automobile body 1 is the inner plate surface. There is an advantage that it is possible to prevent the aesthetic appearance of the vehicle body from being extremely lowered due to the influence of the paint applied to No. 3.

  However, on the other hand, the dust of the second paint sprayed in the second coating film forming step K2 to form the second coating film 6 on the base coating film 4 of the outer plate surface 2 enters the vehicle body, As shown in FIG. 3, there is a possibility of adhering to the peripheral portion of the inner plate surface 3 or the like. When the first coating film 5 and the second coating film 6 are set to different colors, for example, the second coating film 6 is set to an achromatic color, and the first coating film 5 is set to the third color. When it is set to the same or similar chromatic color as the coating film 7, the second coating dust coating film 20 adhered to the inner plate surface 3 and the appearance coating color of the inner plate surface 3 are developed. It was inevitable that the aesthetic appearance deteriorated due to the different hue from the one coating film 5. A clear coating film 8 is formed on the dust coating film 20 and the first coating film 5, but the clear coating film 8 does not have a base concealing property, so that the change in hue is concealed. I can't do it.

  On the other hand, as shown in the first embodiment according to the present invention, the second paint is sprayed on the outer plate surface of the automobile body using the electrostatic coating machine 14 while the automobile body 1 is charged. In the coating method and apparatus for an automobile body to be applied, the potential is applied at a place where the second paint sprayed from the electrostatic coating machine 14 in the second coating film forming step K2 may go around to the inner plate surface 3 side. If the potential difference between the second paint and the outer plate surface 2 of the vehicle body 1 is increased by the suppression means including the control means 22 and the like, compared to when the second paint is sprayed on other portions, the first 2 By positively adsorbing the paint to the outer plate surface 2 electrostatically, the second coating material is prevented from entering the inner plate surface 3 side, and the dust coating film 20 is formed on the inner plate surface 3. It can be effectively prevented.

  Accordingly, the color of the second coating film 6 is set to an achromatic color having five levels of brightness composed of, for example, dark gray, gray, ride gray, super light gray, and white, and the appearance coating is performed only by the third coating film 7. If the film color is developed, or the appearance paint film color is developed by both the second paint film 6 and the third paint film 7, the second paint for the second paint film 6 is versatile. Can be given. For this reason, compared with the case where the second coating film 6 is configured to have the same color as the third coating film 7, the piping necessary for applying the second coating material is reduced and the structure of the coating apparatus is reduced. While effectively simplifying, the effect of reducing the aesthetics caused by the dust of the second paint applied on the outer plate surface 2 of the automobile body 1 adhering to the first coating 5 on the inner plate surface 3 is effective. There is an advantage that can be prevented. In addition, the second coating film 6 is compared with the number of pipe changes performed each time the coating material forming the first and third coating films 5 and 7 that develop appearance coating colors having various colors is changed. There is also an advantage that the number of operations for changing the piping when forming the coating can be greatly reduced to make the painting operation more efficient.

  And since it is not necessary to set the color of the said 2nd coating film 6 to the same or approximate color as an appearance coating film color, as shown in FIG. 4, carbon black 18 is used for the 2nd coating material which forms the 2nd coating film 6. As shown in FIG. Or the like, or by setting the content of the color pigment 19 with respect to the second paint to be higher than usual, the background hiding property of the second coating film 6 is effectively improved. Can be made. Accordingly, by omitting the operation of applying the intermediate coating on the base coating film 4 formed on the outer plate surface 2 and drying it, the process of the painting operation is simplified while the outer coating surface 2 is applied. The irradiation of visible light, ultraviolet rays, or the like is absorbed or reflected by the carbon black 18 or the color pigment 19 blended in the second coating film 6 to prevent the ultraviolet rays from reaching the base coating film 4. it can. For this reason, there exists an advantage that the early deterioration of the base coating film 4 resulting from irradiating the base coating film 4 with an ultraviolet-ray with a simple structure can be prevented effectively.

  In particular, the brightness of the second coating film 6 formed in the second coating film forming step K2 can be set to a third coating film by setting the content of the color pigment 19 with respect to the second coating more than usual as described above. When configured to be set lower than the third coating film 7 formed in the forming step K3, omitting the base concealing pigment composed of the carbon black 18 or the like, or reducing the content thereof, Since the base concealability of the second coating film 6 can be ensured, the early deterioration of the base coating film 4 due to the irradiation of the base coating film 4 with ultraviolet rays can be effectively suppressed with a simpler configuration. There is an advantage that you can.

  Further, as shown in the first embodiment, a clear coating film 8 is formed on the first coating film 5 formed on the inner plate surface 3 of the automobile body 1 at least after the first coating film forming step K1. When the inner plate clear coating film forming step K5 is provided, the smoothness and aesthetics of the inner plate surface 3 can be effectively maintained, and the first coating film 5 is applied to the clear coating film 8. It is possible to effectively improve the weather resistance and the like.

  Further, in the first embodiment, at least after the third coating film forming step K3, the outer coating film 9 is formed on the third coating film 7 formed on the outer plate surface 2 of the automobile body 1. Since the plate clear coating film forming step K6 is provided, the third coating film 7 can be protected by the clear coating film 9 and its weather resistance and smoothness can be effectively maintained. Therefore, even when the clear paint or the like sprayed toward the inner plate surface 3 in the inner plate clear coating film forming step K5 adheres to the third coating film 7 on the outer plate surface 2, the outer plate surface 2 is smooth. It is possible to ensure sufficient properties.

  In the said 1st Embodiment, since the 1st-3rd coating films 5-7 were formed using the 1st-3rd coating material which consists of a water-soluble coating material, an organic solvent is used as a solvent of the said 1st-3rd coating material. In this case, there is an advantage that there is no problem that the solvent evaporated at the time of drying the paint is discharged to the outside. Moreover, since the preheating step K4 for pre-drying the first to third coating films 5 to 7 after application of the first to third coatings made of the water-soluble coating is provided, the subsequent inner plate clear coating film forming step K5 and the outside Even when the clear coating films 8 and 9 are formed on the first and third coating films 5 and 7 in the plate clear coating film forming step K6, moisture in the first to third coating materials is not vaporized. There is no problem such as remaining, and the first to third coating films 5 to 7 made of the first to third paints can be appropriately cured.

  In the first embodiment, the second paint and the automobile are provided at a place where the second paint sprayed from the electrostatic coating machine 14 in the second coating film forming step K2 may go around to the inner plate surface 3 side. Example in which the potential difference with the outer plate surface 2 of the vehicle body 1 is made larger than when the second coating is sprayed on other portions, so that the second coating is prevented from turning around to the inner plate surface side. However, instead of this configuration, as shown in the second embodiment below, the potential applied to the inner plate surface 3 is controlled so that the second paint wraps around the inner plate surface 3 side. You may comprise so that it may suppress.

  That is, when the outer plate surface 2 and the inner plate surface 3 of the automobile body 1 are electrically insulated, or when the electrical resistance between the outer plate surface 2 and the inner plate surface 3 is extremely large, the inner plate The surface 3 is charged with the second paint and the counter electrode to restrict the coating material from flowing to the inner plate surface 3 side, or the potential of the inner plate surface 3 is set lower than that of the outer plate surface 2 and the outer plate surface 2 By controlling the applied potential of the inner plate surface 3 so that the second paint is concentrated on the side, it is possible to prevent the second paint from flowing around to the inner plate surface 3 side. There is an advantage that the formation of the coating film 20 can be effectively prevented.

  Further, as in the third embodiment of the present invention shown in FIG. 5, by providing a restraining means comprising an air blowing device 26 for blowing air W from the inner plate surface 3 side to the outer plate surface 2 through the opening 2a. The second coating material may be configured to prevent the second coating material from flowing around to the inner plate surface side. In this case, since the second paint is scattered due to the air pressure of the air W being too high, its application efficiency may be deteriorated, so that the aesthetic appearance of the application surface is not impaired. It is preferable to control the blowing pressure appropriately.

DESCRIPTION OF SYMBOLS 1 Automobile body 2 Outer plate surface 3 Inner plate surface 4 Base coating 5 First coating 6 Second coating 7 Third coating 8 Clear coating on inner plate 9 Clear coating 12 on outer plate 12 First coating Film forming unit 14 Electrostatic coating machine 15 Second coating film forming unit 17 Third coating film forming unit 22 Potential control means (suppression means)
24 Inner plate clear coating film forming part 25 Outer plate clear coating film forming part 26 Air blowing device (suppression means)

Claims (4)

A first coating film forming step of forming a first coating film for coloring an appearance coating film by applying a first coating material on an inner plate surface of an automobile body on which a base coating film is formed;
A second coating film forming step of forming a second coating film having a base concealing property by applying a second paint on the outer plate surface of the automobile body;
After the second coating film is formed, a third coating material is applied thereon to lower the base concealing property than the second coating film, and the first coating film alone or together with the second coating film. And a third coating film forming step of forming a third coating film that develops an appearance coating color of the same color or an approximate color.
In the second coating film forming step, the vehicle body and the electrostatic coating machine are charged to opposite electrodes to spray the second paint on the outer plate surface of the car body, and the sprayed second paint is the inner plate. In places where there is a possibility of wrapping around the surface, the potential applied to the inner plate surface of the automobile body is controlled to prevent the second paint from wrapping around the inner plate surface while the second coating is applied to the outer plate. A method of painting an automobile body, characterized by being applied to a surface. The method for coating an automobile body according to claim 1, wherein in the second coating film forming step, a second coating film having a lightness lower than that of the third coating film is formed on the outer plate surface. The method for coating an automobile body according to claim 1 or 2 , further comprising an inner plate clear coating film forming step for forming a clear coating film on the inner plate surface after at least the first coating film forming step. The automobile according to any one of claims 1 to 3 , further comprising an outer plate clear coating film forming step for forming a clear coating film on the outer plate surface after at least the third coating film forming step. How to paint the car body.

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