JP2007319762A - Method and apparatus for forming coating film of aqueous coating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a coating film of high quality by controlling the solid component in the coating film while minimizing the quantity of energy consumed and a use space in a coating film forming method of aqueous coating. <P>SOLUTION: In the coating film forming method of the aqueous coating, a work is coated with base coating being the aqueous coating on a base coating stand using a coating robot and a rotary stand is moved to spray air regulated in its humidity and temperature on the work while rotating the coated work. Since the amount of air can be added by rotating the work, a heat source for heating air may be small and consumed energy can be miniaturized, the solid component of the obtained coating film is extremely high and, since the amount of moisture evaporated is extremely small even if clear coating is applied as top coating to be baked, defectiveness such as foaming or the like is not formed in a topcoating film. Further, a conventional preheating zone is dispensed with and a space can be largely conserved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a water-based paint film forming method and a water-based paint film forming apparatus that can obtain a high-quality paint film by controlling the solid content in the paint film.

  Conventionally, the coating of the intermediate coating or the top coating is performed in a coating booth in which the temperature and humidity are controlled within an appropriate range. If the temperature and humidity in the painting booth fluctuate greatly, especially in low temperature and high humidity conditions, the water-based paint may cause sagging of the paint and poor skin of the paint film, making it impossible to form a normal paint film. In addition, in the application of water-based metallic paint, the temperature and humidity in the painting booth have an influence on the orientation of the metallic pigment, so it is necessary to strictly control the temperature and humidity in the painting booth.

  However, since the temperature and humidity are controlled while supplying and exhausting air in the painting booth, the energy consumed for air conditioning in the entire painting booth is enormous, and is generally the largest in industrial painting lines. Reduction was an important issue.

  Therefore, in the invention described in Patent Document 1, a thermosetting water-based colored paint is applied to the surface to be coated, a thermosetting water-based paint containing a metallic pigment is applied thereon, and a thermosetting clear paint is applied from above. In the paint film forming method, after coating the paint, it is heated to simultaneously cure the three-layer paint film. After coating the first layer, high-speed air blow is performed. A coating film forming method is being developed in which air having a controlled temperature and / or humidity is sprayed around the periphery of the film.

  Further, in the invention described in Patent Document 2, in a method of applying a water-based paint to a surface to be coated with a coating gun, a spray paint that is applied to the surface to be coated and the surface to be coated from immediately before the application of the water-based paint to the end of the painting We have developed a coating method and coating equipment for water-based paints that control the solid content of the paints by irradiating the particles with heat rays.

In these inventions, it is possible to widen the allowable range of temperature and humidity in the painting booth while keeping the quality of the formed coating film high, and to greatly reduce the energy consumed for air conditioning in the whole painting booth. I can do it.
JP 2002-113415 A JP 2003-251250 A

  However, in the technique described in Patent Document 1, the amount of air required for painting is enormous, and a large heater unit is required to control the temperature and / or humidity of the air. Moreover, in the technique described in Patent Document 2, a large amount of heat ray irradiation energy is required because it is affected by the surrounding wind speed and the wind of the coating gun itself when it is irradiated with heat rays. As described above, the techniques described in Patent Document 1 and Patent Document 2 have a problem that even if the energy consumption in the painting booth can be reduced, a large amount of energy is required. .

  Accordingly, the present invention provides a method for forming a water-based paint film capable of obtaining a high-quality paint film by controlling the solid content in the paint film while minimizing energy consumption and use space, and a paint film using the water-based paint. It is an object of the present invention to provide a forming apparatus.

The method for forming a coating film of a water-based paint according to the invention of claim 1 includes a step of applying a water-based paint to a workpiece, and increasing the solid content ratio of the coating paint by applying air while rotating the work coated with the water-based paint. A process.
Here, examples of the “water-based paint” include an acrylic emulsion paint, an acrylic lacquer paint, an isocyanate paint, and a water-based metallic paint.

  The method for forming a coating film of a water-based paint according to the invention of claim 2 includes a step of applying a water-based paint to a work, and a solid content ratio of the paint applied by irradiating infrared rays while rotating the work on which the water-based paint is applied. And a step of increasing the temperature.

  According to a third aspect of the present invention, there is provided the method for forming a coating film of an aqueous paint according to the second aspect, wherein the step of increasing the solid content ratio is performed while air is applied to the workpiece.

  According to a fourth aspect of the present invention, there is provided the method for forming a coating film of an aqueous paint according to any one of the first to third aspects, wherein the air is within a range of a wind speed of 0.01 m / s to 0.1 m / s. belongs to.

  According to a fifth aspect of the present invention, there is provided the method for forming a coating film of a water-based paint according to any one of the first to fourth aspects, wherein the temperature of the air is in the range of 20 ° C to 100 ° C and the humidity is 0 Rh. % To 30 Rh%.

A water-based coating film forming apparatus according to a sixth aspect of the invention includes an aqueous paint coating means for applying a water-based paint to a work, a turntable for placing and rotating the work, An air nozzle that applies air to the upper work and an infrared heater that irradiates infrared light to the work on the turntable are provided.
Here, examples of the “water-based paint applying means” include a coating gun, a dipping coating device, and the like.

The method for forming a coating film of a water-based paint according to the invention of claim 1 includes a step of applying a water-based paint to a workpiece and a step of increasing the solid content ratio of the coating material by applying air while rotating the work coated with the water-based paint. It comprises. Here, examples of the “water-based paint” include an acrylic emulsion paint, an acrylic lacquer paint, an isocyanate paint, and a water-based metallic paint.
In the technique described in Patent Document 1, enormous energy is required to produce temperature-humidity controlled air that satisfies both heat and air volume at the same time. However, in the method for forming a coating film of the water-based paint according to the present invention, the air volume can be added by rotating the work, so that the heat source for heating the air can be as small as a general dryer. The energy consumption can be minimized, and even if the temperature and humidity in the painting booth fluctuate, it is not affected.
As a result, the obtained coating film has a very high solid content, and even when the clear coating or the like is subsequently applied and heat-cured (baked), the amount of water volatilized from the coating film of the aqueous coating is extremely small. Therefore, there is no possibility of causing defects such as cracks in the top coat film. In addition, the conventional preheat zone is unnecessary, and the space for the painting process can be saved greatly.
In this way, it is a method for forming a coating film of an aqueous paint that can obtain a high-quality coating film by controlling the solid content in the coating film while minimizing energy consumption and use space.

The method for forming a coating film of a water-based paint according to the invention of claim 2 includes a step of applying a water-based paint to a work, and irradiating infrared rays while rotating the work on which the water-based paint is applied to determine a solid content ratio of the paint. And a step of enhancing.
In the technique described in Patent Document 1, enormous energy is required to produce temperature-humidity controlled air that satisfies both heat and air volume at the same time. However, in the method for forming a coating film of a water-based paint according to the present invention, the air volume can be added by rotating a workpiece, and the heating method for volatilizing water in the water-based paint is by energy-efficient infrared irradiation. Therefore, energy consumption can be minimized, and even if the temperature and humidity in the painting booth fluctuate, they are not affected.
Furthermore, in the method for forming a coating film of a water-based paint according to the invention of claim 1, the paint mist adhering to the coating jig may be blown off by applying air, and there may be a defective defect attached to the workpiece. In the method for forming a coating film of a water-based paint according to the present invention, there is no such fear because air is not blown.
As a result, the resulting coating film has a very high solid content, and even when the clear coating or the like is subsequently applied and heat-cured (baked), the amount of water volatilized from the coating film of the aqueous coating is extremely small. Therefore, there is no possibility of causing defects such as cracks in the top coat film. In addition, the conventional preheat zone is unnecessary, and the space for the painting process can be saved greatly.
In this way, it is a coating film forming method for water-based paints that can obtain a high-quality coating film by controlling the solid content in the coating film while minimizing energy consumption and use space.

In the method for forming a coating film of an aqueous paint according to the invention of claim 3, the step of increasing the solid content ratio is performed while air is applied to the workpiece. In the method for forming a coating film of a water-based paint according to the invention of claim 2, an air volume can be added by rotating a workpiece, and a heating method for volatilizing water in the water-based paint is based on infrared irradiation with high energy efficiency. As a result, energy consumption can be minimized. In addition, since air is not blown, there is no possibility that the paint mist is blown off by air and the sticking defect adhering to the work is generated.
However, if air is not blown at all, there is a risk that water vapor will fill the periphery of the workpiece and the water volatilization efficiency will deteriorate. Therefore, in the method for forming a coating film of a water-based paint according to the present invention, the water volatilization efficiency can be further improved without causing defects by applying air that does not cause the paint mist to be blown off.
In this way, it is a coating film forming method for water-based paints that can obtain a high-quality coating film by controlling the solid content in the coating film while minimizing energy consumption and use space.

In the method for forming a coating film of a water-based paint according to the invention of claim 4, the air is in a range of a wind speed of 0.01 m / s to 0.1 m / s.
Thus, in addition to the effects of claims 1 to 3, by applying air within a range of wind speed of 0.01 m / s to 0.1 m / s at which the paint mist is not likely to be blown, It is possible to improve the volatilization efficiency of water without giving off.
In this way, it is possible to obtain a high-quality coating film by controlling the solid content in the coating film while minimizing energy consumption and use space, and to improve the coating efficiency. This is a film forming method.

In the method for forming a coating film of an aqueous paint according to the invention of claim 5, the air temperature is in the range of 20 ° C to 100 ° C, more preferably in the range of 40 ° C to 80 ° C, and the humidity is 0 Rh% to 30 Rh%. More preferably, it is in the range of 0 Rh% to 20 Rh%.
The inventor has conducted extensive experimental research to determine a more appropriate air temperature and humidity range in the method of forming a coating film of an aqueous paint according to the present invention. As a result, the air temperature is 20 ° C to 100 ° C. High quality coating film when the humidity is in the range of 40 ° C. to 80 ° C., and the humidity is in the range of 0 Rh% to 30 Rh%, more preferably in the range of 0 Rh% to 20 Rh%. Has been found more reliably, and the present invention has been completed based on this finding.
In this way, it is a method for forming a coating film of an aqueous paint that can more reliably obtain a high-quality coating film by controlling the solid content in the coating film while minimizing energy consumption and use space.

  Here, in the method for forming a coating film of a water-based paint according to any one of claims 1 to 5, it is more preferable to perform the work while rotating the work also in the step of applying the water-based paint to the work. As a result, in the case where a plurality of relatively small workpieces are set at a time for coating, or in the case of a workpiece that needs to be coated on both the front and back surfaces, the effect of improving the coating efficiency can be obtained. In this way, it is possible to obtain a high-quality coating film by controlling the solid content in the coating film while minimizing energy consumption and use space, and to improve the coating efficiency.

A water-based coating film forming apparatus according to a sixth aspect of the invention comprises an aqueous paint coating means for applying a water-based paint to a work, a turntable for placing and rotating the work, and a top of the turntable. An air nozzle that applies air to the work and an infrared heater that irradiates the work on the turntable with infrared light are provided. Here, examples of the “water-based paint applying means” include a coating gun, a dipping coating device, and the like.
In the coating apparatus for forming a water-based paint according to the present invention, after the water-based paint is applied to the work by means of a water paint-coating means such as a paint gun, the work is placed on a turntable and rotated with an infrared heater to the work. To evaporate the water in the water-based paint. The air volume can be added by rotating the workpiece, and since the energy efficient infrared heater is used as the heat source to volatilize the water in the water-based paint, energy consumption can be minimized and painting can be performed. Even if the temperature and humidity in the booth fluctuate, it will not be affected.
As a result, the resulting coating film has a very high solid content, and even when the clear coating or the like is subsequently applied and heat-cured (baked), the amount of water volatilized from the coating film of the aqueous coating is extremely small. Therefore, there is no possibility of causing defects such as cracks in the top coat film. In addition, since the solid content ratio in the coating film can be controlled while drying the water-based paint applied to the workpiece, the conventional preheating zone is not required, and the coating film forming apparatus space can be greatly saved. .
In this way, the coating film forming apparatus for water-based paints can be obtained, which can obtain a high-quality coating film by controlling the solid content in the coating film while minimizing energy consumption and use space.

Here, instead of the water-based paint film forming apparatus according to the invention of claim 6, an aqueous paint application means for applying the aqueous paint to the work, a turntable for placing and rotating the work, It is also possible to use a water-based paint film forming apparatus that includes an air nozzle that applies temperature- and humidity-adjusted air to a work on a turntable. In such a water-based coating film forming apparatus, after applying a water-based paint to a work by means of a water paint application means such as a paint gun, the work is placed on a turntable and rotated while the work is placed on the turntable by an air nozzle. By applying air with temperature and humidity adjusted to the work, air volume can be added by rotating the work, so the heat source for heating the air can be as small as a general dryer, Energy consumption can be minimized, and even if the temperature and humidity in the painting booth fluctuate, it will not be affected.
As a result, the resulting coating film has a very high solid content, and even when the clear coating or the like is subsequently applied and heat-cured (baked), the amount of water volatilized from the coating film of the aqueous coating is extremely small. Therefore, there is no possibility of causing defects such as cracks in the top coat film. Moreover, the conventional preheating zone becomes unnecessary and the space of the coating film forming apparatus can be saved greatly.
In this way, the coating film forming apparatus for water-based paints can be obtained, which can obtain a high-quality coating film by controlling the solid content in the coating film while minimizing energy consumption and use space.

  Moreover, in the coating film forming apparatus for water-based paint according to the invention of claim 6, the air nozzle applies air within a range of wind speed of 0.01 m / s to 0.1 m / s to the work on the turntable. More preferably. In the coating film forming apparatus for water-based paint according to the invention of claim 6, the air volume can be added by rotating the workpiece, and an energy efficient infrared heater is used as a heat source for volatilizing water in the water-based paint. Thus, energy consumption can be minimized. However, if air with a too high wind speed is blown, the paint mist may be blown off by the air, resulting in defects that adhere to the workpiece. Therefore, by applying air with a wind speed of 0.1 m / s or less that does not cause the paint mist to be blown off, the volatilization efficiency of moisture can be further improved without causing defects. In this way, the coating film forming apparatus for water-based paint can obtain a high-quality coating film by controlling the solid content in the coating film while minimizing energy consumption and use space.

  Further, in the coating apparatus for forming a water-based paint according to the invention of claim 6, a turntable for placing and rotating the work can also be used when the water-based paint is applied to the work by the water-based paint applying means. . As a result, when painting with several relatively small workpieces set at once, or for workpieces that must be painted on both front and back surfaces, the coating efficiency can be improved because it can be applied while rotating. The effect is obtained. In this way, it is possible to obtain a high-quality coating film by controlling the solid content in the coating film while minimizing energy consumption and use space, and to improve the coating efficiency. It becomes a film forming apparatus.

  Furthermore, in the water-based coating film forming method according to any one of claims 1 to 5 or the water-based coating film forming apparatus according to the invention of claim 6, the rotation speed of the workpiece is 1 rpm to 200 rpm. More preferably, it is within the range of 10 rpm to 100 rpm. The inventor has conducted extensive experimental studies to determine a more appropriate work rotation speed in the water paint coating film forming method and water paint coating film forming apparatus according to the present invention. Has been found that a high-quality coating film can be obtained more reliably when it is within the range of 1 rpm to 200 rpm, more preferably within the range of 10 rpm to 100 rpm. In this way, it is possible to control the solid content in the coating film while minimizing energy consumption and use space, and to obtain a high-quality coating film more reliably, It becomes a coating film forming apparatus.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a water-based paint film forming method and a water-based paint film forming apparatus according to embodiments of the present invention will be described with reference to the drawings.

Embodiment 1
First, an aqueous paint film forming method and an aqueous paint film forming apparatus according to Embodiment 1 of the present invention will be described with reference to FIGS. 1 to 3.
FIG. 1 is a block diagram showing the configuration of a water-based paint film forming apparatus and the procedure of a water-based paint film forming method according to Embodiment 1 of the present invention. FIG. 2 is a perspective view showing a workpiece set on a turntable in the aqueous paint coating film forming apparatus according to Embodiment 1 of the present invention. FIG. 3 is an explanatory view showing a method for an adhesion test of a coating film obtained by the coating film forming apparatus for an aqueous paint and the coating film forming method for an aqueous paint according to the first embodiment of the present invention.

  As shown in FIG. 1, an aqueous paint film forming apparatus 1 according to the first embodiment has a coating booth 2, a post-clear application setting zone 3, and a baking zone 22, and is degreased and neutralized. The object to be painted (work) is put into the painting booth 2. First, a workpiece is placed on the base coating table 20 and base coating is performed. A base paint, which is a water-based paint, is pumped from the paint tank 18 </ b> A by the pump 17 </ b> A, and the base paint is applied to the work on the base paint stand 20 by the paint gun 16 of the paint robot 15.

After the base coating is completed, setting and preheating are simultaneously performed in the (setting + preheating) zone for leveling the coating surface and for volatilizing water.
In setting, the workpiece is set on the turntables 6A, 6B and 6C, the sprocket 5 is rotated by the rotation motor 4, and the rotation of the sprocket 5 is transmitted to the sprocket integrally attached to the turntable 6B by the chain 7. Then, by further transmitting to the sprocket integrally attached to the turntables 6A and 6C with another chain 7, the turntables 6A, 6B and 6C rotate at the same rotation speed.

  The rotation speeds of the turntables 6A, 6B, 6C can be freely set by controlling the rotation speed of the rotary motor 4 with the rotation controller 4a. The number of rotations of the turntables 6A, 6B, 6C is preferably in the range of 1 rpm to 200 rpm, and more preferably in the range of 10 rpm to 100 rpm. Air blow is performed by the air nozzles 8A, 8B, and 8C on the workpieces on the turntables 6A, 6B, and 6C rotating in this way.

  As shown in FIG. 1, the air jetted from the air nozzles 8A, 8B, 8C is dried with primary air (compressed air) compressed by an air compressor with a dryer 12 to remove moisture, and with an air filter 11 Oil and dust are removed for purification, and the product is heated by a heater 9 and supplied. The temperature of the supplied air is maintained within a predetermined temperature range by controlling the heating by the heater 9 with the air temperature controller 10.

  The temperature of the air jetted from the air nozzles 8A, 8B, 8C is preferably in the range of 20 ° C to 100 ° C, and more preferably in the range of 40 ° C to 80 ° C. Moreover, it is preferable that the humidity of the injected air is in the range of 0 Rh% to 30 Rh%, and more preferably in the range of 0 Rh% to 20 Rh%. By drying the primary air with the dryer 12, the humidity of the injected air is maintained within the range of 0 Rh% to 20 Rh%, and the temperature of the injected air is controlled by the air temperature controller 10 to be heated by the heater 9. By this, it is kept within the range of 40 ° C to 80 ° C.

  In the first embodiment, as shown in FIG. 1, one air nozzle 8A, 8B, 8C is provided for each work on the turntables 6A, 6B, 6C. Depending on the case, a plurality of air nozzles may be provided for each work in order to apply air evenly to the entire surface, or a method of moving the air nozzles 8A, 8B, 8C using a reciprocating device or the like may be used. .

  By setting and rotating the work on the turntables 6A, 6B, and 6C in this way, the amount of air hitting the work is increased and drying of the base paint is promoted, and the centrifugal force due to the rotation is applied. Water in the base paint is efficiently removed, and the solid content ratio in the coating film can be improved.

  At the same time, the base paint on which the work is heated and applied by air blowing by the air nozzles 8A, 8B, and 8C to the work on the turntables 6A, 6B, and 6C with air whose humidity and temperature are controlled. Is further promoted, and the solid content ratio in the coating film can be improved to a predetermined ratio or more.

  A specific example of the workpiece in the aqueous paint coating film forming apparatus 1 according to the first embodiment will be described with reference to FIG. Here, as shown in FIG. 2, as a specific example of the workpiece W, a case where a door handle (door outside handle) of a door of an automobile is painted with a water-based paint is shown. On the turntable 6A, five door handles W coated with a base paint are supported and fixed in the vertical direction at the upper end and the lower end by the support 6Aa.

  Here, the rotary table 6A is rotated at a predetermined rotational speed (50 rpm to 100 rpm) by the rotary motor 4, and the air nozzle 8A is provided for the five door handles W supported on the rotary table 6A by the support 6Aa. To air having a humidity temperature controlled to a humidity of 20 Rh% or less and a temperature of 40 ° C. to 80 ° C.

  In the example shown in FIG. 2, the coating robot 15 is rotated while the base coating table 20 is also rotated at 100 rpm while the five door handles W are supported on the base coating table 20 by the support 6Aa. The base paint is applied by the coating gun 16A, and the support 6Aa is moved onto the turntable 6A while the five door handles W are supported, and the air blow by the air nozzle 8A is performed. The

  Therefore, the example shown in FIG. 2 is the “water-based coating film forming method characterized in that the water-based coating material is formed by rotating the workpiece in the step of applying the water-based coating material to the workpiece” and “water-based coating material coating means”. This corresponds to a coating film forming apparatus for water-based paint characterized by using a turntable for placing and rotating the work even when applying the water-based paint to the work.

  As a result, when a plurality of door handles W, which are relatively small workpieces, are set and painted at a time, and when the door handle W is a workpiece that must be painted on both the front and back surfaces, the painting efficiency is improved. The effect is obtained.

  The test result of the drying of the base paint in the aqueous paint film forming apparatus 1 according to the first embodiment will be specifically described. In the first embodiment, the test was performed under the four conditions of Example 1 to Example 4 while changing the work rotation speed, air temperature, air humidity, air wind speed, and the like. For comparison, Comparative Example 1 in which the workpiece is not rotated and air blow is not performed, Comparative Example 2 in which the workpiece is not rotated and only air blow is performed, and Comparative Example 3 in which only the workpiece is rotated without performing air blow is compared. Were also tested.

  Then, as shown in FIG. 1, the workpiece is moved to the clear coating table 21, and the clear paint pumped from the paint tank 18B by the pump 17B is sprayed from the paint gun 16 of the paint robot 15 to perform the base paint. After the clear coating was applied on the surface and the coating surface was leveled in the setting zone 3 after the clear coating, the coating material adhered to the work was thermally cured in the baking zone 22 and was baked at a specified baking temperature and baking time. . The test conditions of Examples 1 to 4 and Comparative Examples 1 to 3 are shown in the upper part of Table 1.

  As shown in Table 1, Example 1 and Example 2 differ in the number of rotations of the workpiece and the rotation time (and hence the air blow time), and the other conditions are the same. Further, Example 2 and Example 3 are different in air temperature, air humidity, and air wind speed, and other conditions are the same. Furthermore, Example 3 and Example 4 are the same except that the booth humidity is different. However, in any of Example 1 to Example 4, the air temperature is in the range of 40 ° C. to 80 ° C., the air humidity is in the range of 0 Rh% to 20 Rh%, and the work rotation speed is 10 rpm to 100 rpm. Within range.

  On the other hand, in Comparative Examples 1 to 3, the booth temperature is 25 ° C. and the booth humidity is 70 Rh%, which is the same as those in Examples 1 to 3. The air temperature and air humidity in Comparative Example 2 -Air wind speed and air blow time are the same as Example 1, and the rotation speed and rotation time of the workpiece | work in Comparative Example 3 are the same as Example 1.

  The results of the coating test under such test conditions are shown in the lower part of Table 1. As shown in Table 1, the solid coating content in the base coating film after passing through the (setting + preheating) zone was 95% in Example 1, 90% in Example 2, and 90% in Example 3. Example 4 shows an extremely high value of 92%. On the other hand, Comparative Example 1 is 45%, Comparative Example 2 is 65%, and Comparative Example 3 is 55%, both of which remain low, indicating that the amount of residual moisture in the base coating film is large.

  In addition, as for the appearance after painting after baking in the baking zone 22, all of Examples 1 to 4 are good without any occurrence of cracks, whereas in Comparative Examples 1 to 3 In both cases, the armpit has occurred and the appearance after painting is impaired.

  Furthermore, about the adhesiveness of the coating film, using the plate-shaped test piece S, it tested as follows. As shown in FIG. 3 (a), the coating SP of the test piece S after baking was cut with a cutter knife CN using a cutter guide, and as shown in FIG. A grid (100 squares) G is created. Thereafter, as shown in FIG. 3 (b), air is drawn on the grid G as much as possible and the adhesive tape TP is pasted so that the angle formed between the coating film SP and the adhesive tape TP is 45 degrees. Peel off vigorously and check how many squares of the grid (100 squares) G have been peeled off.

  And when even one of 100 squares is peeled off, it is determined as unacceptable and only when no one is removed is determined as acceptable. In this Embodiment 1, in order to serve also as a water resistance test of the coating film, the appearance of the coating surface SP is wrinkled after the test piece S is immersed in 40 ° C. ± 1 ° C. ion exchange water in a constant temperature bath for 240 hours. The adhesiveness test was carried out within 10 minutes after the test piece S was taken out of the thermostatic chamber after checking for swelling.

  As a result, as shown in Table 1, none of the grids (100 squares) G was peeled off in any of Examples 1 to 4, and both the water resistance test and the adhesion test were acceptable. On the other hand, in Comparative Examples 1 to 3, no wrinkles or blisters occurred on the appearance of the coated surface after being immersed in ion-exchanged water for 240 hours. About 10 squares of them were peeled off, and the adhesion test was rejected.

  As shown in the above results, in the water-based paint film forming method according to Examples 1 to 4, as shown in Table 1, the coating in the base paint film after passing through the (setting + preheating) zone was performed. Since the solid solid content rate is extremely high, the adhesiveness is excellent, and the residual moisture is very small, the upper clear coating film is not adversely affected during baking in the baking zone 22.

  On the other hand, in Comparative Examples 1 to 3, as shown in Table 1, the coating solid content rate in the base coating film after passing through the (setting + preheating) zone is low, and there is a lot of residual moisture. A large amount of water vapor is generated at the time of baking, and the clear film of the upper layer is cracked and the adhesion is inferior.

  As described above, in the water-based paint film forming apparatus 1 and the water-based paint film forming method according to the first embodiment, the air volume can be added by rotating the workpiece, so that the air is heated. The heat source can be a general dryer 12, energy consumption can be minimized, and even if the temperature and humidity in the painting booth 2 fluctuate, it is not affected.

  And since the obtained coating film has a very high solid content, the amount of water volatilized from the coating film of the aqueous paint is extremely small even if the clear paint is subsequently applied and heat-cured (baked), There is no possibility of causing defects such as cracks in the top coat film. Further, since the solid content ratio in the coating film can be controlled while drying the water-based paint applied to the workpiece, a conventional preheat zone is not required as shown in FIG. Can save a lot.

  Thus, in the water-based paint film forming apparatus 1 and the water-based paint film forming method according to the first embodiment, the solid content in the paint film is controlled while minimizing energy consumption and use space. Thus, a high quality coating film can be obtained.

Embodiment 2
Next, an aqueous paint film forming method and an aqueous paint film forming apparatus according to Embodiment 2 of the present invention will be described with reference to FIG.
FIG. 4: is a block diagram which shows the structure of the coating-film formation apparatus of the aqueous coating material concerning Embodiment 2 of this invention, and the procedure of the coating-film formation method of an aqueous coating material.

  As shown in FIG. 4, the water-based paint film forming apparatus 25 according to the second embodiment has a coating booth 2, a post-clear application setting zone 3, and a baking zone 22, and a degreasing / static discharge process. The object to be painted (work) is put into the painting booth 2. First, a workpiece is placed on the base coating table 20 and base coating is performed. A base paint, which is a water-based paint, is pumped from the paint tank 18 </ b> A by the pump 17 </ b> A, and the base paint is applied to the work on the base paint stand 20 by the paint gun 16 of the paint robot 15.

After the base coating is completed, setting and preheating are simultaneously performed in the (setting + preheating) zone for leveling the coating surface and for volatilizing water.
In setting, the workpiece is set on the turntables 6A, 6B and 6C, the sprocket 5 is rotated by the rotation motor 4, and the rotation of the sprocket 5 is transmitted to the sprocket integrally attached to the turntable 6B by the chain 7. Then, by further transmitting to the sprocket integrally attached to the turntables 6A and 6C with another chain 7, the turntables 6A, 6B and 6C rotate at the same rotation speed.

  The rotation speeds of the turntables 6A, 6B, 6C can be freely set by controlling the rotation speed of the rotary motor 4 with the rotation controller 4a. The number of rotations of the turntables 6A, 6B, 6C is preferably in the range of 1 rpm to 200 rpm, and more preferably in the range of 10 rpm to 100 rpm. Infrared irradiation is performed by infrared heaters 26A, 26B, and 26C on the workpieces on the turntables 6A, 6B, and 6C rotating in this manner.

  Here, as the infrared heaters 26A, 26B, and 26C, a medium wavelength infrared heater having a peak wavelength of irradiated infrared rays of 2.6 μm may be used, or a far wavelength having a peak wavelength of irradiated infrared rays of 4.0 μm may be used. An infrared heater may be used. The aqueous paint film forming apparatus 25 according to the second embodiment uses medium-wavelength infrared heaters 26A, 26B, and 26C that have high energy density and can be heated from the inside of the paint film and can shorten the preheating time. ing.

  Further, as shown in FIG. 4, in the aqueous paint coating film forming apparatus 25 according to the second embodiment, small air nozzles 27A, 27B, and 27C are provided adjacent to the infrared heaters 26A, 26B, and 26C. Provided. The air supplied to these air nozzles 27A, 27B, and 27C is obtained by drying the primary air (compressed air) compressed by an air compressor with a dryer 12 to remove moisture, and the air filter 11 to remove oil and dust. It is also used when painting with the painting gun 16 of the painting robot 15.

  As described above, by setting and rotating the work on the turntables 6A, 6B, and 6C, the amount of air hitting the work is increased and the drying of the base paint is promoted, and the centrifugal force due to the rotation is applied. Thus, moisture in the base paint can be more efficiently removed, and the solid content ratio in the coating film can be improved. At the same time, the workpiece is heated by the medium wavelength infrared heaters 26A, 26B, and 26C being irradiated with medium wavelength infrared rays having a peak wavelength of 2.6 μm to the workpiece on the turntables 6A, 6B, and 6C. Drying of the applied base paint is further promoted, and the solid content ratio in the coating film can be improved to a predetermined ratio or more.

  A test result of drying of the base paint in the aqueous paint film forming apparatus 25 according to the second embodiment will be specifically described. In the second embodiment, the test was performed under the three conditions of Examples 5 to 7 by changing the number of rotations of the workpiece, the presence or absence of air blowing, the infrared peak wavelength, and the like. For comparison, three types of conditions of Comparative Example 1 to Comparative Example 3 in Embodiment 1 above and air blow exceeding the wind speed of 0.1 m / s are performed by rotating the workpiece without irradiating infrared rays. Tests were also conducted on Comparative Example 4 (Example 3) and Comparative Example 5, and Comparative Example 6 in which only the infrared irradiation was performed without rotating the workpiece and without performing air blowing.

  Then, as shown in FIG. 4, the workpiece is moved to the clear coating table 21, and the clear paint pumped by the pump 17B from the paint tank 18B is sprayed from the paint gun 16 of the paint robot 15, so that the base coating is performed. After the clear coating was applied on the surface and the coating surface was leveled in the setting zone 3 after the clear coating, the coating material adhered to the work was thermally cured in the baking zone 22 and was baked at a specified baking temperature and baking time. . The test conditions of Examples 5 to 7 and Comparative Examples 1 to 6 are shown in the upper part of Table 2.

  As shown in Table 2, Example 5 and Example 6 differ in work rotation speed and infrared peak wavelength, and other conditions are the same including the air wind speed. Moreover, Example 6 and Example 7 differ only in the presence or absence of the blowing of air, and other conditions are the same. And throughout Example 5-Example 7 and Comparative Example 1-Comparative Example 6, the booth temperature is 25 ° C. and the booth humidity is 70 Rh%, which is the same.

The results of the coating test under such test conditions are shown in the lower part of Table 2. As shown in Table 2, the solid coating content in the base coating film after passing through the (setting + preheating) zone was 93% in Example 5, 94% in Example 6, and 91% in Example 7. Both show extremely high values. On the other hand, Comparative Example 1 is 45%, Comparative Example 2 is 65%, and Comparative Example 3 is 55%, both of which remain low, indicating that the amount of residual moisture in the base coating film is large.
However, in the case of workpiece rotation and air blow or infrared irradiation, Comparative Example 4 is 90%, Comparative Example 5 is 92%, and Comparative Example 6 is 92%, all showing extremely high values.

  Moreover, as for the appearance after coating after baking in the baking zone 22, all of Examples 5 to 7 are good without any occurrence of cracks, whereas Comparative Examples 1 to 3 and Comparative Example In Example 6, all of the cracks occurred, and the appearance after coating was impaired. On the other hand, Comparative Example 4 and Comparative Example 5 are all good with no occurrence of cracks.

  Furthermore, the adhesiveness of the coating film was tested in the same manner as in Embodiment 1 using a plate-shaped test piece S as shown in FIG. And when even one of 100 squares is peeled off, it is determined as unacceptable and only when no one is removed is determined as acceptable. Also in the second embodiment, in order to serve as a water resistance test of the coating film, the appearance of the coating surface SP is wrinkled after the test piece S is immersed in 40 ° C. ± 1 ° C. ion exchange water in a constant temperature bath for 240 hours. The adhesiveness test was carried out within 10 minutes after the test piece S was taken out of the thermostatic chamber after checking for swelling.

  As a result, as shown in Table 2, none of the grids (100 squares) G peeled off in Examples 5 to 7, and both the water resistance test and the adhesion test passed. In Comparative Example 1 to Comparative Example 3 and Comparative Example 6, wrinkles and blisters did not occur on the appearance of the coated surface after being immersed in ion exchange water for 240 hours. About 10 squares of the square were peeled off, and the adhesion test was rejected. On the other hand, as for Comparative Example 4 and Comparative Example 5, none of the grids G peeled off, and both the water resistance test and the adhesion test passed.

  Furthermore, in this Embodiment 2, it evaluated also about the coating defect rate and the coating efficiency. That is, when the air speed of the air blow exceeds 0.1 m / s, there is an increased possibility that the coating mist is blown off with air and the defect that adheres to the workpiece is generated. As shown in Table 2, for Examples 5 to 7, the coating failure rate due to defects was very low at 0.1% to 0.2%, but for Comparative Example 4, The coating failure rate due to defects is 3.5%, and in Comparative Example 5, the coating failure rate due to defects is 6.0%.

  Similarly, as for the coating efficiency, both Examples 5 to 7 showed high results of 28% to 29%, while Comparative Examples 4 and 5 both had 22%. It was a low number. Thus, in the aqueous paint coating film forming methods of Examples 5 to 7 according to the second embodiment, the appearance after coating and the adhesion after coating are the same as those in Comparative Example 4 and Comparative Example 5. Good results were obtained, and more excellent results were obtained as compared with Comparative Example 4 and Comparative Example 5 with respect to the defective coating rate and application efficiency.

  Thus, in the water-based paint film forming apparatus 25 and the water-based paint film forming method according to the second embodiment, since the air volume can be added by rotating the work, the work is heated. Infrared heaters with excellent energy efficiency can be used as the heat source, and energy consumption can be minimized. Even if the temperature and humidity in the coating booth 2 fluctuate, they are not affected.

  And since the obtained coating film has a very high solid content, the amount of water volatilized from the coating film of the aqueous paint is extremely small even if the clear paint is subsequently applied and heat-cured (baked), There is no possibility of causing defects such as cracks in the top coat film. Further, since the solid content ratio in the coating film can be controlled while drying the water-based paint applied to the workpiece, as shown in FIG. 4, the conventional preheating zone is not required, and the space for the painting process is eliminated. Can save a lot.

  Thus, in the water-based paint film forming apparatus 25 and the water-based paint film forming method according to the second embodiment, the solid content in the paint film is controlled while minimizing energy consumption and use space. Thus, a high quality coating film can be obtained.

  In each of the above embodiments, since a non-water-based paint is used as the clear paint, a (setting + preheat) zone is provided in the painting booth 2 only for the base paint that is a water-based paint. However, in the case of using a water-based paint, it is necessary to provide a (setting + preheat) zone having a turntable for clear paint and an air nozzle in the painting booth 2.

  In each of the above-described embodiments, the case where a door handle is painted as an example of the workpiece W has been described. However, the workpiece W may have various sizes such as an automobile handle (steering), a spoiler, and the like. Various thicknesses and shapes can be painted with water-based paint.

  In carrying out the present invention, the other steps of the water-based paint film forming method, and the configuration, shape, quantity, material, size, connection relationship, etc. of other parts of the water-based paint film forming apparatus, The present invention is not limited to the above embodiments.

FIG. 1 is a block diagram showing the configuration of a water-based paint film forming apparatus and the procedure of a water-based paint film forming method according to Embodiment 1 of the present invention. FIG. 2 is a perspective view showing a workpiece set on a turntable in the aqueous paint coating film forming apparatus according to Embodiment 1 of the present invention. FIG. 3 is an explanatory view showing a method for an adhesion test of a coating film obtained by the coating film forming apparatus for an aqueous paint and the coating film forming method for an aqueous paint according to the first embodiment of the present invention. FIG. 4 is a block diagram showing the configuration of the aqueous paint film forming apparatus and the procedure of the aqueous paint film forming method according to the second embodiment of the present invention.

Explanation of symbols

1,25 Water-borne paint film forming apparatus 6A, 6B, 6C Turntable 6Aa Support 8A, 8B, 8C Air nozzle 26A, 26B, 26C Infrared heater W Work

Claims (6)

  Forming a water-based paint film, comprising: applying a water-based paint to a work; and increasing the solid content ratio of the paint by applying air while rotating the work to which the water-based paint is applied Method.   A step of applying a water-based paint to a work; and a step of increasing the solid content ratio of the paint by applying infrared rays while rotating the work on which the water-based paint is applied. Film forming method.   The method for forming a coating film of a water-based paint according to claim 2, wherein the step of increasing the solid content ratio is performed while air is applied to the workpiece.   The method for forming a coating film of a water-based paint according to any one of claims 1 to 3, wherein the air has a wind speed within a range of 0.01 m / s to 0.1 m / s. .   5. The water-based paint according to claim 1, wherein a temperature of the air is in a range of 20 ° C. to 100 ° C., and a humidity is in a range of 0 Rh% to 30 Rh%. Coating film forming method. A water-based paint applying means for applying a water-based paint to a work, a turntable for placing and rotating the work, an air nozzle for applying air to the work on the turntable, and a top of the turntable An aqueous paint film forming apparatus comprising: an infrared heater that irradiates the workpiece with infrared rays.

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