JP4848810B2 - Coating method and coating apparatus - Google Patents

Description

  The present invention relates to a coating method and a rotary atomizing type coating apparatus for spraying a coating material containing a scaly glitter pigment on an object to be coated such as an automobile body or an automobile part.

  In order to improve the appearance finish of paints containing scaly glittering pigments such as aluminum flakes and mica foil, especially the flip-flop property called metallic feeling, a coating method that increases the flying speed of paint particles has been proposed. (Patent Documents 1 and 2).

  To increase the flying speed of paint particles, increase the flow rate of atomizing air or pattern air for air atomizing paint guns, and increase the flow rate of shaping air for rotary atomizing paint guns. Thus, a method is generally used in which a large amount of air flow toward the object to be coated is formed to impart speed to the paint particles.

  This is a coating method based on the knowledge that the larger the collision speed of paint particles, the easier the scaly glittering pigment is oriented in parallel to the substrate, thereby making it easier to obtain a coating film with excellent flip-flop properties. .

  However, in the conventional coating method using a large amount of air, an excessive air flow is formed on the surface of the object to be coated, and a relatively fine and lightweight paint particle is carried away. was there.

  For example, the application efficiency of an air atomizing paint gun is about 30 to 45%, and even when a metallic base paint is applied even with a rotary atomizing paint gun which is said to have high application efficiency. There is still room for improvement compared to the coating efficiency of about 80% in the case of applying a clear paint or solid paint containing no scaly glittering pigment.

  For this reason, in the process of applying the metallic base paint, after applying a relatively thick film in the first stage under a coating condition that emphasizes the coating efficiency, a relatively thin film is applied in the second stage together with the above-mentioned large amount of air. A two-stage coating method is used in which finish is ensured by painting.

  In this case, a rotary atomizing paint gun with excellent coating efficiency is used for the first stage, but the coating conditions are such that the shaping air flow rate is reduced so that the coating efficiency is high, thereby reducing the coating efficiency. Increase to 70-80%. In the second stage, an air atomizing paint gun or a rotary atomizing paint gun set to a large amount of shaping air flow is used, but as a result of the large amount of air flow, the coating efficiency is limited to about 60%. It becomes.

  In addition, if the two-stage coating method is used, the number of coating equipment (painting guns) will inevitably increase, which causes a problem of increased equipment costs. As a result, there is a problem that the amount of paint to be discarded at the time of color change and the cleaning liquid also increase.

Furthermore, since the effective pattern width is inevitably narrow in the painting method using a large amount of air, the number of times of painting must be increased, and the painting gun must be moved to paint a predetermined area within a limited painting time. I had to increase the speed. As a result, there is a problem that the failure rate of the robot equipped with the paint gun is increased.
JP 2003-93965 A Japanese Patent No. 2560421

  An object of this invention is to provide the coating method and coating apparatus which can obtain the coating film which has high coating efficiency and high metallic feeling with the one-stage coating method.

In order to achieve the above object, the coating method of the present invention is a coating method in which a coating containing a scaly glittering pigment is atomized and coated on an object using a rotary atomizing coating gun, The peripheral speed of the bell cup of the rotary atomizing paint gun is controlled according to the average particle diameter or content concentration of the scaly glittering pigment contained in the paint, and the average of the paint when applied to the object to be coated The paint is atomized and applied so that the particle diameter is equal to or less than the average particle diameter of the scaly glittering pigment.

The rotary atomizing coating apparatus of the present invention is a rotary atomizing coating apparatus that atomizes and paints a paint containing at least a scale-like glitter pigment on an object to be coated, and adjusts the peripheral speed of the bell cup. According to a peripheral speed controller, a paint supply system for supplying paint to the bell cup, and an average particle diameter or content concentration of the scaly glitter pigment contained in the paint supplied to the bell cup by the paint supply system The peripheral speed of the bell cup of the rotary atomizing paint gun is controlled so that the average particle diameter of the paint when applied to the object is equal to or less than the average particle diameter of the scaly glitter pigment. And a control means.

In the present invention, when atomizing a paint containing a scaly glitter pigment, the average particle diameter at the time of application is a scaly depending on the average particle diameter or the concentration of the scaly glitter pigment contained in the paint. The peripheral speed of the bell cup is controlled so as to be equal to or less than the average particle size of the pigment-like glittering pigment, so that the scaly glittering pigment is oriented almost in parallel on the surface of the object to be coated without using a large amount of shaping air. Thus, a coating film having a high metallic feeling can be obtained. In other words, since a coating film that exhibits a good metallic feeling can be obtained with a small amount of shaping air, the effective pattern width can be increased and the coating process can be reduced.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a process diagram showing an example of a painting process in which the present invention is used, FIG. 2 (A) is a plan view showing an example of a topcoat booth in which the present invention is used, and FIG. 2 (B) is an example of a conventional topcoat booth. FIG. 3 is a front view and a side view showing an example of a scaly glitter pigment according to the present invention, FIG. 4 is a schematic diagram for explaining a coating mechanism according to the present invention, and FIG. 5 is a rotary atomization. FIG. 6 is a graph showing the relationship between the average particle size of paint particles and metallic feeling (IV value) when a base paint containing scaly glitter pigment is applied using a paint gun, and FIG. FIG. 7 is a graph showing the relationship between the shaping air flow rate and the coating efficiency when a base paint containing scaly glittering pigment is used, and FIG. 7 shows the film thickness distribution when applied using a rotary atomizing paint gun. Figure 8 shows a scaly shape using a rotary atomizing paint gun. A graph and a micrograph showing the relationship between the average particle diameter of paint particles and the black-and-white concealed film thickness when a base paint containing a luster pigment is applied, and FIG. 9 shows an example of a rotary atomizing paint gun according to the present invention. FIG. 10 is a cross-sectional view, FIG. 10 is a plan view and a side view showing an example of a method for painting an automobile body according to the present invention, and FIG. 11 is a side view for explaining an effective pattern width according to the present invention.
First, an outline of a car body painting line will be described with reference to FIG. 1. First, a white body assembled in a vehicle body line is carried into an undercoating process. In this undercoating process, the oil and iron powder adhering to the white body are washed, and then surface adjustment and chemical conversion film treatment such as zinc phosphate are applied (the above is the cleaning and pretreatment process), and the undercoating film is further formed Electrodeposition coating is performed. A body coated with an electrodeposition coating material having an epoxy resin such as polyamine resin as a base resin is carried into an electrodeposition drying furnace and baked at 160 to 180 ° C. for 15 to 30 minutes, for example. An electrodeposition coating film having a thickness of 10 μm to 35 μm is formed on the plate and the bag structure (electrodeposition process).

  The body on which the electrodeposition coating has been formed is sent to the sealing process (including the undercoat process and the stone guard coat process), and vinyl chloride is used for the purpose of rust prevention or sealing at the steel plate joints and steel plate edges. A resin-based sealing material is applied. In the undercoat process, a vinyl chloride resin-based chipping-resistant material is applied to the tire house and floor, and in the stone guard coat process, a polyester-based or polyurethane-based resin chipping is applied to the lower part of the body outer plate such as a sill or fender. The material is applied. In addition, these sealing materials and chipping-resistant materials are cured in a dedicated drying furnace or an intermediate coating drying furnace described below.

  The body on which the sealing material and the chipping-resistant material are applied and the electrodeposition coating film is formed on the inner and outer plates is then carried into the intermediate coating process. The intermediate coating process has an intermediate coating booth and an intermediate coating drying furnace. In the intermediate coating booth, an inner panel coating paint corresponding to the outer panel color of the vehicle is applied to the inner panel of the body, and then wet. An intermediate coating is applied to the outer plate part on wet. This body is conveyed to an intermediate coating drying furnace, and an intermediate coating film having a film thickness of 15 μm to 35 μm is formed on the outer plate by passing through the intermediate coating drying furnace at 130 to 150 ° C. for 15 to 30 minutes, for example. A coating film for inner plate coating having a film thickness of 15 μm to 30 μm is formed on the inner plate portion. The inner coating paint and the intermediate coating paint are paints using an acrylic resin, alkyd resin, polyester resin, or the like as a base resin.

  After finishing the intermediate coating, the body is sanded as needed and then transported to the top coating process. When the outer color is metallic, the top coating base paint and clear paint are applied wet-on-wet. Is done. In the case of a solid-type outer plate color, a top-coated solid paint is applied in the clear coating process. The topcoat base paint, clear paint, and topcoat solid paint are paints that use acrylic resin, alkyd resin, polyester resin, or the like as a base resin.

  Then, the body to which the top coat is applied is conveyed to a top coat drying furnace, where it is baked at, for example, 130 to 150 ° C. for 15 to 30 minutes, thereby forming a top coat film. The film thickness of the clear coating film is, for example, 15 μm to 30 μm, and the film thickness of the top coating solid coating film is, for example, 15 μm to 35 μm. However, when the coating method of the present invention is used as described later, the film of the top coating base coating film The thickness can be reduced from the conventional 10 μm to 20 μm to 8 μm to 16 μm.

  Finally, the coated body is subjected to an inspection and rework process, and then conveyed to an assembly line on which automobile parts are assembled.

  The above is the outline of the painting line of the automobile body, and the coating method of the present invention is suitably used in the top coating base coating process of the top coating process.

  The coating method of this example is a method in which a metallic base paint containing aluminum flakes or a pearl base paint containing mica foil as a paint containing scaly glitter pigment is applied to the surface of the intermediate coating film. The paint is atomized so that the average particle size of the paint when applied to the film surface is less than or equal to the average particle size of the scaly glitter pigment. Controls at least one of the peripheral speed and the shaping air flow rate of the bell cup of the paint gun.

  Here, depending on the type of paint, the average particle diameter and the concentration of the scaly glitter pigment contained in the paint differ depending on the color of the paint and the desired metallic feeling. Since the average particle diameter of the scale-like glitter pigment contained in the paint is known, in order to make the paint average particle diameter at the time of application equal to or less than the average particle diameter of the scale-like glitter pigment, the peripheral speed of the bell cup ( Is proportional to the rotation speed of the bell cup.), And the shaping air flow rate is used as a control factor in order to enlarge the effective pattern width as compared with the conventional case.

  In general, when applying a top coat base paint, either a rotary atomizing paint gun or an air atomizing paint gun can be used as a paint gun for atomizing the paint. Therefore, it is preferable to use a rotary atomizing paint gun.

  In addition, the coating flight speed is not particularly limited as long as the particle size of the base coating when applied to the surface of the intermediate coating film is approximately equal to or less than the average particle size of the scaly glitter pigment, but the coating efficiency is not particularly limited. From this point of view, it is preferable that the flight speed at the time of applying the paint is less than 5 m / sec.

  In addition, when the above-mentioned predetermined film thickness of 8 μm to 16 μm is formed on the surface of the intermediate coating film, it may be applied by two or more stages of coating, but from the viewpoint of coating efficiency, the base paint is applied in one stage. It is preferable to do.

  The metallic paint and the pearl base paint may be organic solvent-based paints, but the effect of the present invention is particularly great when they are water-based paints. This is because the organic solvent-based paint evaporates during the flight and the particle size just before coating is slightly reduced, but the water-based paint does not change much.

  By the way, the luster pigment 1 contained in the base paint according to this example has a scaly shape as shown in FIG. 3, and the radius R when the real area in a plan view is converted into a circle 2 is defined as the present invention. Is defined as the average particle size. That is, the average particle diameter of the scaly glittering pigment referred to in the present invention means not the thickness t shown in the figure but the average diameter R of the main surface. The average particle diameter R of the glitter pigment contained in the base paint according to this example is generally about 10 to 30 μm, and the thickness is about 0.2 to 1 μm. Therefore, when the average diameter of the principal surface of the scale-like glitter pigment contained is 20 μm, the particle diameter at the time of application of the paint is reduced to 20 μm or less for coating.

  Here, the average particle diameter of the paint particles can be controlled by the discharge amount of the paint and the peripheral speed of the bell cup of the rotary atomizing coating gun. However, the discharge range of the paint has a limit in the control range depending on the target film thickness. Therefore, in this example, the peripheral speed of the bell cup (the rotation speed of the bell cup if the diameter of the bell cup is constant) is controlled.

  The particle size at the time of coating can be measured using a laser light scattering type particle size measuring device. An image processing measurement system that takes this measurement and calibration can also be used. In the latter method, a fluorosurfactant is applied to a thin film on a glass plate, and the plate is exposed to the surface of the object to be coated for about 1 second. The coating particles collected in this manner can be easily measured by enlarging them with a microscope and measuring the particle diameter. In the present invention, the weight average particle diameter of the paint particle diameters thus measured is used as the average particle diameter of the paint particles.

  According to this example, when applying a base paint containing scaly bright pigments such as aluminum flakes and mica foil, the average particle diameter of the paint particles at the time of application (or immediately before application) is the average of the bright pigments. By making it smaller than the particle size, it is possible to improve the orientation of the glitter pigment without forming a large amount or high-speed air flow, thereby improving the finished appearance of the coating film and improving the coating efficiency. .

  Thus, in the absence of high-speed air flow, the relationship between the particle size of the paint and the orientation of the glitter pigment has not been known so far, but the paint particle diameter is small, especially the average particle diameter of the glitter pigment. When the particle diameter is equal to or less than the above, a remarkable effect is exhibited, so that the present inventors have a special effect on the orientation of the glitter pigment when the paint particle diameter is small. I came to a conclusion.

  That is, it is concluded that the surface tension when the coating particles are applied is a factor governing the orientation of the glitter pigment. In other words, the direction of the glitter pigment is not fixed inside the paint particles that are atomized and in the middle of flight, and are expected to be random with respect to the object to be coated. However, when paint particles are applied, there is an effect of smoothing the surface by surface tension when fusing with the paint already applied and covering the surface of the object to be coated. According to the above, it is inferred that the glitter pigment is pulled in parallel with the paint surface by the surface tension because the scaled glitter pigment having almost the same size is contained in the deposited paint particles. In this orientation by surface tension, it is considered that the same force is applied as when the paint particles are crushed on the surface of the object by increasing the collision speed of the paint particles.

  In contrast, when the paint particles are coated with paint particles having an average particle size larger than the average particle size of the glitter pigment, even if the paint particles flow so as to be smooth due to the surface tension, the glitter within the paint particles. Since the luminescent pigment has a certain degree of freedom in orientation, it is considered that it is not completely parallel to the surface of the object to be coated, and it is assumed that the orientation of the glitter pigment is insufficient.

  In addition, when the average particle diameter of the paint particles is much smaller than the average particle diameter of the glitter pigment, it can be regarded as the glitter material being applied alone, so that the orientation is considered to be good. That is, when the glitter pigment is applied alone to the object to be coated, the glitter pigment is most preferably applied to the object to be coated on the widest surface, that is, the main surface (planar portion) of the scaly glitter pigment. This is considered to be stable, whereby the main surface of the scale is oriented in parallel with the object to be coated, and a finished appearance of the coating film exhibiting a good metallic feeling can be obtained.

  This state is shown in FIGS. In the figure, reference numeral 1 is a scaly glitter pigment, reference numeral 3 is a paint particle, reference numeral 4 is an object to be coated, and FIG. 4A shows two paint particles 3 each containing a scaly glitter pigment 1. The state which is flying toward the to-be-coated object 4 is shown. When the lower coating particles 3 arrive at the surface of the article 4 to be coated (A), the coating particles 3 are smoothed by the surface tension along the surface of the article 4 as shown in FIG. It will flow and spread radially. At this time, the glitter pigment 1 contained in the paint particle 3 cannot have a degree of freedom inside the paint particle 3 because the particle diameter of the paint particle 3 is smaller than its own particle diameter. The main surface moves along the surface of the article 4 to be coated. As shown in FIG. 3C, when the paint particles 3 spread on the surface of the object 4 to be coated, the glitter pigment 1 is also included in the paint particles 3 in a state of being oriented parallel to the surface of the object 4 to be coated. Will be. By such a coating mechanism, each coating particle 3 is deposited on the surface of the object 4 to form a coating film, so that a coating film in which the glitter pigment 1 is oriented parallel to the surface of the object 4 is obtained. Can do.

  FIG. 5 shows the average particle diameter of paint particles and metallic feeling (IV value and IV value are large when a base paint containing scaly glitter pigment having an average particle diameter of 22 μm is applied using a rotary atomizing paint gun. And the metallic feeling is also large.), And the shaping air flow rate of the rotary atomizing paint gun is 100 to 500 NL / min. According to this, it is understood that even if the shaping air flow rate is 200 NL / min, the metallic sensation IV value can be increased to 200 or more if the average particle size of the paint particles is 22 μm or less. Therefore, in this example, the shaping air flow rate is controlled in the range of 100 to 200 NL / min according to the type of paint.

  Of course, if the shaping air flow rate is 400 NL / min or more, a metallic feeling with an IV value of 200 or more can be obtained even if the average particle size of the paint particles is as large as 30 μm. However, if the shaping air flow rate is increased, the coating efficiency is increased. There is a problem that decreases.

  FIG. 6 is a graph that verifies the relationship between the shaping air flow rate and the coating efficiency when a base paint containing scaly bright pigment having an average particle diameter of 22 μm is applied using a rotary atomizing paint gun. The amount of paint discharged is 50 to 200 cc / min. According to this, if the shaping air flow rate is suppressed to 200 NL / min or less, the coating efficiency can be increased to 80% or more at a discharge rate of 100 to 200 cc / min. On the other hand, when the above-described shaping air flow rate is 400 NL / min, it is less than 80% even when the discharge rate is 200 cc / min.

  As described above, according to this example, the metallic feeling can be easily revealed without increasing the shaping air flow rate as in Patent Documents 1 and 2, so that a high coating can be achieved by suppressing the shaping air flow rate. It becomes easy to obtain the deposition efficiency, and it is possible to realize the coating efficiency almost equal to that of the clear coating or the intermediate coating.

  In addition, when painting with a rotary atomizing electrostatic coating machine, it is possible to select an arbitrary shaping air flow rate while painting a paint containing a glittering pigment, and the accompanying effect that the coating pattern width can be set freely. There is.

  Furthermore, as an incidental effect of this example, the pattern distribution can be made relatively flat by reducing the shaping air flow rate of the rotary atomizing paint gun. The pattern distribution here refers to the film thickness distribution in the direction perpendicular to the traveling direction of the coating gun when the coating gun is moved along the surface of the workpiece. However, as shown by the dotted line in FIG. 7, it is common to have a so-called two cobra camel-type film thickness distribution in which two film thickness peaks appear, and this tendency is seen in metallic base coating using a large amount of shaping air flow Appears prominently.

  However, according to this example, as indicated by a solid line in the figure, since the shaping air flow rate is suppressed to about 200 NL / min or less, the pattern distribution can be made into a trapezoidal shape with a substantially flat shape. The effect that so-called metallic unevenness due to the difference (referred to as unevenness) is almost eliminated is obtained.

  Furthermore, as another effect of this example, when the metallic base paint is used, the base concealment film thickness can be reduced. This is because, in the case of opaque glittering pigments such as aluminum flakes, the orientation of the glittering pigment not only improves as the atomization progresses and the average particle diameter decreases, but it is also applied uniformly to the surface of the object to be coated. This is because they tend to wear.

  This means that as the average particle size of the paint particles decreases, the number of particles increases and the number of coatings increases, resulting in the elimination of uneven coating amount due to the surface area of the object to be coated. Means that you can plan. If this effect is used, the discharge amount of the metallic base paint itself can be reduced, and the coating cost can be reduced.

  By using these effects in combination, it is possible to apply the metallic base paint that has been applied in two stages in one stage and reduce the number of color changes.

  FIG. 8 verified the relationship between the average particle diameter of paint particles and the black-and-white concealment film thickness when a base paint containing scaly bright pigment having an average particle diameter of 22 μm was applied using a rotary atomizing paint gun. In the graphs and micrographs, when the average particle size of the paint particles is reduced to 20 μm, the black-and-white concealment film thickness is reduced to almost half compared to the case where the average particle size of the paint particles is 56 μm.

  An example of the overcoating process using the above features is shown in FIG. An example of a rotary atomizing paint gun used in this embodiment is shown in FIG. Furthermore, FIG. 10 shows an example of a coating trajectory of the coating gun in the top coating base process shown in FIG. 2A, and FIG. 11 shows an explanation of an effective pattern by the rotary atomizing coating gun.

  First, the rotary atomizing paint gun used in the present embodiment will be described. As shown in FIG. 9, the rotary atomizing electrostatic paint gun 5 of the present embodiment has a rotary shaft 520 with air in a housing 510. The motor 511 is rotatably supported by a motor 511, and a bell cup 530 is fixed to the tip of the rotating shaft 520 at a bell hub portion 534. The bell cup 530 of this example has a diameter of 50 mm, and rotates at a speed of about 20,000 to 90,000 rpm and a circumferential speed of about 50 to 240 m / sec during painting. The coating gun 5 of this example can be switched at a desired rotational speed between 20,000 rpm and 90,000 rpm, for example, by a rotational speed adjuster 512. The rotation speed adjuster 512 corresponds to a peripheral speed adjuster according to the present invention.

    In addition, a plurality of paint holes 536 are formed in the gap between the inner peripheral surface 532 of the bell cup 530 and the bell hub portion 534, and the paint nozzle 550 that is pumped from the paint supply system 551 and inserted through the rotary shaft 520. The coating material supplied to the back surface of the bell hub portion 534 from the front end of the bellows is guided to the inner peripheral surface 532 of the bell cup 530 through these coating material holes 536. Although not shown in the drawings, the tip of the inner peripheral surface 532 of the bell cup 530 is formed with fine irregularities for atomizing the paint P spreading in a liquid film shape along the inner peripheral surface 532. Yes. An applied voltage circuit (not shown) is electrically connected to the rotating shaft 520, and a DC voltage of about −60 kV, for example, is applied to the bell cup 530 through the rotating shaft 520.

    In the rotary atomizing electrostatic coating gun 50 of this embodiment, an air guide 540 is fixed between the housing 510 and the bell cup 530, and an air guide surface 542 is formed on the entire outer surface of the air guide 540. Has been. The air guide 540 is inserted into the housing 510 via an O-ring or the like. At this time, the air guide 540 is fixed to the housing 510 side by being screwed into the housing 510.

    An annular air passage 516 is formed between the housing 510 and the housing cover 514, and the annular air passage 516 communicates with a plurality of air passages 544 formed in the air guide 540. Further, the air passage 544 communicates with an air outlet 546 described later.

    The air outlet 546 of this embodiment is formed of an annular slit having an air guide surface 542 of the air guide 540 as an inner peripheral surface and an inner surface of the housing cover 514 as an outer peripheral surface. That is, after the air guide 540 is screwed into the housing 510, the housing cover 514 is screwed outside the air guide 540, so that a slit-like air blow is formed between the housing cover 514 and the air guide surface 542 of the air guide 540. An outlet 546 is formed, and the shaping air supplied from the air passages 544 and 516 is blown out from the air outlet 546 toward the bell cup 530 in an annular shape.

    In this example, the flow rate of the shaping air SA that is blown out from the air outlet 546 is adjusted by, for example, 50 NL / min, 100 NL / min, and 150 NL / min by a shaping air flow rate adjuster 560 configured by an air regulator or the like. Minutes, 200 NL / min, and 250 NL / min can be adjusted in multiple steps (digital) or continuously between 50 and 250 NL / min (analog).

  Further, the shaping air flow rate adjuster 560 and the rotation speed adjuster 512 are controlled by the control device 570. The control device 570 includes an arithmetic device and a storage device, takes in the paint color specification of the automobile body sent from the production management system, and controls the shaping air flow rate corresponding to this paint color and the rotation speed of the bell cup. Is read out from the storage device, and data is sent to each of the shaping air flow rate controller 560 and the rotational speed controller 512.

  In the storage device of the control device 570, data of the shaping air flow rate and the bell cup rotation speed corresponding to each of the paints of the paint color are mapped. For example, the average particle size of the scale-like glitter pigment contained in the paint The number of rotations of the bell cup according to the diameter and the content concentration is set in advance, and the shaping air flow rate is set in advance so as to have an effective pattern width according to the coating color.

  The paint color data sent from the production management system is also sent to the paint supply system 551, whereby a color change operation is executed.

  The above-described rotary atomizing paint gun 5 is installed on the top coat base stage of the paint booth 6 shown in FIG. In the example shown in the figure, two left and right coating robots RB are arranged on the top coat base stage, and a rotary atomizing paint gun 5 is provided on the hand of the painting robot RB. In addition, two painting robots RB on the left and right sides are also arranged on the clear painting stage across the flash-off zone.

  As described above, when topcoat base paint is applied on the topcoat base stage, according to the coating method of this example, (1) a metallic feeling can be easily revealed without increasing the shaping air flow rate. Therefore, high coating efficiency can be obtained by suppressing the shaping air flow rate, (2) the effective pattern width can be expanded by reducing the shaping air flow rate, and (3) the shaping air flow rate is reduced. As a result, the film thickness distribution of the pattern can be made relatively flat, and (4) the scale-like glitter pigment is oriented parallel to the surface of the object to be coated and the underlying hiding power is increased. Since there is an effect that the film thickness can be reduced by about 20%, the top coat base paint can be finished in one stage. Therefore, in the top coat base stage shown in FIG. 2 (A), the painting ranges of the painting robots RB hardly overlap each other, and each painting site is painted.

  In particular, in this example, since the shaping air flow rate is reduced to about 100 to 200 NL / min, the effective pattern width can be increased. Here, the effective pattern width refers to a pattern width having an average film thickness of 50% or more out of the pattern widths painted by the rotary atomizing paint gun 5 when the gun distance is 300 mm (see FIG. 11). In this example, the effective pattern width of the painting gun 5 provided in each painting robot RB is set to 800 mm ± 50 mm with respect to the conventional around 400 mm.

  In this way, for example, when painting the horizontal surface (mainly hood, roof, trunk lid, etc.) of the automobile body B shown in FIG. 10 (A), the vehicle width W of the automobile body B is 1550 to 1850 mm. As shown in the figure, if the painting range of the vehicle width W is arranged so that it can be evenly painted by the two painting guns 5, 5, the vehicle can be moved without reciprocating the painting guns 5, 5 in the left-right direction of the vehicle. It is possible to paint a horizontal plane simply by moving it in the front-rear direction. In the drawing, a dotted line around the coating gun 5 indicates an effective pattern width, and a chain line indicates a relative movement locus of the coating gun 5.

  When painting the vertical surface (mainly front fender, door, rear fender, etc.) of the automobile body B shown in FIG. 10B, the height H from the door belt line of the automobile body B to the sill outer is 700 to 900 mm. Therefore, if one painting gun 5 is arranged at the center of the coating area of height H as shown in the figure, the painting gun 5 can be moved relative to the longitudinal direction of the vehicle without reciprocating in the vertical direction of the vehicle. The vertical surface can be painted just by moving it. In the drawing, a dotted line around the coating gun 5 indicates an effective pattern width, and a chain line indicates a relative movement locus of the coating gun 5.

  The relative movement between the automobile body B and the painting gun 5 is a combination of conveying the automobile body B at a constant speed by a conveyor, fixing the painting gun 5, stopping the automobile body B, and using the painting robot 5 with the painting gun 5. Either a combination of moving at a constant speed or a combination of moving the painting gun 5 by the painting robot RB while conveying the automobile body by a conveyor may be adopted. This relative speed is mainly determined by the discharge amount of the coating gun 5 and the target film thickness.

  As described above, when the coating method of the present invention is employed, one stage of the top coating base can be omitted and the length of the top coating booth 6 can be shortened as compared with the conventional two-stage coating method shown in FIG. can do. In addition, since the number of coating guns 5 can be reduced, it is possible to reduce the amount of paint discarded when changing colors.

  The embodiment described above is described for facilitating the understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

It is process drawing which shows an example of the coating process in which this invention is used. (A) is a top view which shows an example of the topcoat booth in which this invention is used, (B) is a top view which shows an example of the conventional topcoat booth. It is the front view and side view which show an example of the scaly glittering pigment which concerns on this invention. It is a schematic diagram for demonstrating the coating mechanism which concerns on this invention. It is a graph which shows the relationship between the average particle diameter of paint particle | grains and metallic feeling (IV value) when the base coating material containing a scaly glittering pigment is applied using the rotary atomization type painting gun. It is a graph which shows the relationship between the shaping air flow rate and coating efficiency when the base coating material containing a scaly glittering pigment is applied using a rotary atomizing paint gun. It is a figure which shows film thickness distribution when it paints using a rotary atomization type painting gun. It is the graph and micrograph which show the relationship between the average particle diameter of a coating particle when a base coating material containing a scaly glittering pigment is applied using a rotary atomizing coating gun, and the black-and-white concealment film thickness. It is sectional drawing which shows an example of the rotary atomization type painting gun which concerns on this invention. It is the top view and side view which show an example of the coating method of the motor vehicle body which concerns on this invention. It is a side view for demonstrating the effective pattern width | variety which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Scale-like luster pigment 3 ... Paint particle 4 ... Coated object 5 ... Paint gun 512 ... Speed controller (circumferential speed controller)
560 ... Shaping air flow controller 570 ... Control device (control means)

Claims (16)

A coating method for atomizing and painting a paint containing scaly glittering pigment using a rotary atomizing paint gun,
The coating material when applied to the substrate by controlling the peripheral speed of the bell cup of the rotary atomizing coating gun according to the average particle diameter or the concentration of the scaly glitter pigment contained in the coating material. The coating method is characterized in that the paint is atomized and applied so that the average particle diameter of the pigment is equal to or less than the average particle diameter of the scaly glittering pigment. 2. The coating method according to claim 1, wherein the shaping air flow rate is controlled according to the type of the paint, and the paint is atomized so as to exceed a predetermined metallic feeling characteristic value (IV). The coating method according to claim 1 or 2, wherein a peripheral speed of the bell cup of the rotary atomizing coating gun is controlled in a range of 180 to 240 m / sec. 4. The coating method according to claim 2, wherein a shaping air flow rate of the rotary atomizing paint gun is controlled in a range of 100 to 200 NL / min. The coating method according to any one of claims 1 to 4, wherein the effective pattern width of the rotary atomizing paint gun when the gun distance to an object is 300 mm is 800 ± 50 mm. . The object to be coated is an automobile body, and the two rotary atomizing paint guns are arranged with respect to the horizontal plane of the automobile body so that the painting range with the effective pattern width of 800 ± 50 mm is substantially uniform, 6. The coating method according to claim 5, wherein the rotary atomizing paint gun is relatively moved only in the front-rear direction of the automobile body to paint the horizontal surface. The object to be coated is an automobile body, and one rotary atomizing paint gun is arranged with respect to the vertical plane of the automobile body so that the center of the bell cup is substantially the center in the vertical direction of the vertical plane. 7. The coating method according to claim 5, wherein the vertical surface is painted by relatively moving the rotary atomizing paint gun only in the longitudinal direction of the automobile body. The coating method according to any one of claims 1 to 7, wherein the coating material containing the scaly glitter pigment is applied to the object to be coated in one stage. A rotary atomizing coating apparatus that atomizes and paints a paint containing at least a scaly glitter pigment on an object,
A peripheral speed controller for adjusting the peripheral speed of the bell cup;
A paint supply system for supplying paint to the bell cup;
According to the average particle diameter or the concentration of the scaly glitter pigment contained in the paint supplied to the bell cup by the paint supply system, the average particle diameter of the paint when applied to the object to be coated is And a control means for controlling a peripheral speed of a bell cup of the rotary atomizing paint gun so as to be equal to or less than an average particle diameter of the scaly glittering pigment. . A shaping air flow controller for adjusting a shaping air flow rate is provided, and the control means exceeds a predetermined metallic feeling characteristic value (IV) according to the type of paint supplied to the bell cup by the paint supply system. The rotary atomizing coating apparatus according to claim 9, wherein the shaping air flow rate is controlled as described above. The rotary atomizing coating apparatus according to claim 9 or 10, wherein the control means controls the peripheral speed of the bell cup in a range of 180 to 240 m / sec. The rotary atomizing coating apparatus according to claim 10 or 11, wherein the control means controls the shaping air flow rate in a range of 100 to 200 NL / min. 13. The control means according to claim 9, wherein the effective pattern width of the rotary atomizing paint gun is 800 ± 50 mm when the gun distance to the object is 300 mm. Rotating atomizing coating device described in 1. The object to be coated is an automobile body, and the two rotary atomizing coating apparatuses are arranged so that the painting range with the effective pattern width of 800 ± 50 mm is uniform with respect to the horizontal plane of the automobile body, The rotary atomizing coating apparatus according to claim 13, wherein the horizontal surface is painted by relatively moving a bell cup only in the front-rear direction of the automobile body. The object to be coated is an automobile body, and one rotary atomizing coating device is arranged with respect to the vertical surface of the automobile body so that the center of the bell cup is substantially the center in the vertical direction of the vertical surface. The rotary atomizing coating apparatus according to claim 13 or 14, wherein the vertical cup is painted by relatively moving the bell cup only in the front-rear direction of the automobile body. The rotary atomizing coating apparatus according to any one of claims 9 to 15, wherein the coating material containing the scaly glitter pigment is applied to the object to be coated in one stage.

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