JP2006231238A - Water paint collecting apparatus and coating booth - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a collecting apparatus capable of effectively decreasing foaming and collecting water paint mist in the case of spray coating using water paint. <P>SOLUTION: In the collecting apparatus (29) for collecting the water paint, a 1st flow passage (15) through which a gas containing the water paint mist (9a) and 1st booth water (12) flow and a 1st recovery vessel (17) for recovering the 1st booth water (12) passed through the 1st flow passage (15) are arranged, wherein at least one bending part (15a) is provided in the 1st flow passage (15) and the 1st booth water (12) flows with the gas through the bending part (15a) while forming a liquid film covering the inside wall surface of the 1st flow passage (15). As a result, the water paint mist (9a) in the gas is collected in the 1st booth water (12). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a water-based paint, and more particularly to a collection device for collecting water-based paint contained in a mist form in a gas. The present invention also relates to a painting booth equipped with such a collecting device and used for painting an article to be coated with a water-based paint.

  As a general coating method, a spray coating method of spraying (or spraying) a coating material on an object to be coated is widely used (see, for example, Patent Documents 1 to 6). In such a spray coating method, a paint that has not been applied to an object to be coated during coating may exist in a mist state in a gas atmosphere (hereinafter, also referred to as a paint mist in this specification). There is a wet (or flush) paint booth that uses water or booth water to collect the paint mist.

  As an example of a conventional wet painting booth, a painting booth using a water curtain will be described with reference to the drawings.

  A painting booth 60 shown in FIG. 7A includes a painting chamber 61 and an exhaust path 81. In the painting chamber 61, a work 65 that is an object to be coated is painted. While painting is performed, an air flow is formed by the blower fan 63 and the exhaust fan 83 as indicated by an arrow in the figure, and the gas atmosphere in the painting chamber 61 is forcibly exhausted through the exhaust path 81.

  In the painting chamber 61, the water curtain 71 is formed by causing the booth water in the booth water tank 73 to flow down from the riser 78 along the flat plate. The water curtain 71 is located on the opposite side of the spray nozzle 67 with the work 65 interposed therebetween. The painting is performed by spraying the paint 69 from the spray nozzle 67 toward the work 65. Of the sprayed paint, most of the paint not applied to the work 61 reaches the water curtain 71. Collected in the water. Further, as shown in FIG. 7B, the paint mist 69 a that may be present in the gas in the coating chamber 61 is formed in the water curtain 71 from the gap between the flat plate behind the water curtain 71 and the centrifugal plate 75. Is collected in water using centrifugal force applied to the paint when passing through the coating at high speed (such centrifugal plates are shown in FIGS. 1 and 2 (vortex plate) of Patent Document 2, FIG. 3 of Patent Document 5 and Patent (See FIG. 1 of document 6). The collected paint is collected in a booth water tank (recovery tank) 73 in the form of booth water.

  The gas that has passed through the water curtain 71 rises in the exhaust path 81, passes through baffle plates 77 that are alternately inclined as shown in the figure, passes through the filter 79, and is discharged to the outside. At this time, the paint mist 69a remaining in the gas (and the water that may be present) is removed from the gas by the baffle plate 77 and the filter 79, and the paint mist 69a colliding with the baffle plate 77 is collected in the booth water tank 73. . The baffle plate 77 generally has a size over the entire width of the exhaust passage 81 (length in the direction perpendicular to the paper surface of FIG. 7A). When the baffle plate 77 and the filter 79 are washed while the painting is performed, water droplets are scattered to adversely affect the painting. The filter 79 is replaced during maintenance.

JP 05-146727 A Japanese Patent Laid-Open No. 06-142573 Japanese Patent Laid-Open No. 07-1000041 JP 07-299399 A Japanese Patent Application Laid-Open No. 09-10640 JP 2000-126659 A

  In recent years, water-based paints have been used in place of solvent-based paints from the viewpoints of the influence on the environment and the human body and ease of reuse.

  However, the conventional water curtain paint booth as described above is not fully satisfactory when using a water-based paint. Since the air current passes through the water curtain 71 at high speed and the air current and the water collide with the centrifugal plate 75, forced gas-liquid mixing occurs. This is because the foam that has become overflowed from the booth tank 73. When using a solvent-type paint, the wind speed of the airflow when passing through the water curtain 71 is about 20 to 35 m / s. However, when using a water-based paint, foaming occurs when the wind speed exceeds 10 m / s. Is an upper limit wind speed of 15 m / s at the maximum, and a sufficient collection rate cannot be obtained if foaming is to be suppressed.

  The problem of foaming can be dealt with by adding antifoaming agents and using antifoaming equipment, but these require additional costs, and in the case of concentrating and reusing booth water that collects paint mist. Addition of a large amount of antifoaming agent is not desirable because the composition of the recovered paint changes.

  Conventionally, a venturi-type paint booth that uses a throttle channel to collect paint mist is also known (see, for example, Patent Document 1), but water or booth water is also used in such a paint booth. Foaming can occur when atomizing through the venturi (or throttle channel) with paint mist at high speed. In addition, the venturi has a complicated structure and it is difficult to clean the inside.

  In addition, in the conventional painting booth, the internal structure is complicated, so the cleaning performance is poor, and it is necessary to lengthen the cleaning time when performing color change. Moreover, since the amount of contamination is large, usable paint colors are limited.

  Furthermore, in the conventional painting booth, water-based paint adheres to the inside of the exhaust passage (more specifically, a filter and a baffle plate), and it is necessary to frequently perform maintenance, which is expensive.

  The object of the present invention is to effectively reduce and preferably prevent foaming even in the case of spray coating using a water-based paint, to collect paint mist while improving cleanability and reducing maintenance frequency. It is an object of the present invention to provide a collection device capable of performing the above and a painting booth including the same.

According to one aspect of the present invention, a collecting device for collecting a water-based paint,
A first flow path through which a gas containing a mist-like aqueous paint and a first booth water flow;
A first recovery tank that recovers the first booth water that has passed through the first flow path, the first flow path has at least one bent portion, and the first booth water covers the inner wall surface of the first flow path. A collecting device is provided that flows through the first flow path together with the gas while forming a liquid film, thereby collecting the aqueous paint contained in the gas in a mist form in the first booth water. Hereinafter, in the present specification, the first flow path and the first recovery unit are also referred to as a primary collection unit.

  According to such a collection device of the present invention, the first booth water flows with the gas while forming a liquid film covering the inner wall surface of the first flow path, so that the first booth water and the gas are not vigorously mixed. , Foaming can be effectively reduced and preferably prevented. Further, since the first booth water and the gas flow together in the first flow path having the bent portion, the water-based paint mist contained in the gas is collected in the first booth water by the inertial force, and the first recovery tank Can be recovered. Furthermore, according to such a collecting device, most of the water-based paint can be quickly collected in the first booth water without fixing the water-based paint to the inner wall surface, and the first flow path can be made relatively clean. Can be maintained (in other words, it is highly cleanable). As a result, the frequency of maintenance of the first flow path can be reduced, and the cleaning can be performed with a smaller amount of cleaning water (or cleaning agent), and the first recovery tank can be made compact by reducing the amount of cleaning water. it can. In addition, since the pressure loss during passing through the first flow path is small, noise can be further reduced.

  Throughout the present invention, “booth water” refers to water or a liquid fluid containing water as a main component and water-based paint collected. As the “water-based paint”, a general water-based paint, that is, a water-based paint containing a nonvolatile content and an aqueous solvent can be used. Nonvolatile components constituting the water-based paint are paint resin and pigment.

  In the present invention, the “bent portion” of the first flow path means that the first flow path is refracted or curved so as to change the direction of gas flow (ie, air flow). By changing the air flow direction, the water-based paint mist moves in a direction deviating from the air flow direction due to the inertial force, and collides with the first booth water covering the inner wall surface of the first flow path and is collected. Such a bent portion only needs to change the airflow direction at least once, but is preferably changed twice or more in order to further increase the collection efficiency of the water-based paint mist.

  In order for the first booth water to cover the inner wall surface of the first flow path and form a liquid film, it is important that the first booth water exhibits good wettability with respect to the inner wall surface. The wettability can be evaluated by the contact angle of the first booth water with respect to the inner wall surface of the first flow path. This contact angle is, for example, within about 60 °, and is preferably as small as possible. When such a contact angle is exhibited, the liquid film can be formed so as to cover the entire inner wall surface of the flow path without the film being interrupted or the liquid being scattered or dripped.

  The contact angle is determined by the combination of the composition of the liquid material for forming the liquid film and the material constituting the inner wall surface of the first flow path. The first booth water collected in the first collection tank is reused for this liquid, but the booth water contains the hydrophilic solvent contained in the water-based paint, has the advantage that the surface tension is small and a liquid film is easily formed. . On the other hand, the material constituting the inner wall surface of the first flow path is preferably a material having a hydrophilic surface. For example, a material subjected to hydrophilic treatment by coating or surface modification can be used. Moreover, it is preferable that the inner wall surface is smooth and smooth.

  Furthermore, in order to avoid gas-liquid mixing, it is preferable that the first booth water covering the inner wall surface of the first flow path and forming a liquid film does not drip off the inner wall surface, and the water-based paint is applied to the inner wall surface. In order to avoid sticking, it is preferable that the first booth water appropriately flows along the inner wall surface. For this reason, the inclination angle of the inner wall surface of the first flow path, particularly the inner wall surface at the bent portion, can be limited in consideration of the above-described wettability, the gas passing wind speed, the flow rate of the first booth water, and the like. The inner wall surface of the first flow path is inclined at an angle in the range of, for example, about 15 to 165 ° with respect to the horizontal plane (even at the bent portion). This angle (also referred to as an inclination angle in the present specification) is an angle between the inner wall surface and the horizontal plane, and when the inner wall surface is curved, it is an angle between the tangential plane of the curved surface and the horizontal plane. It shall mean the angle of the exposed side of the wall surface (the side in contact with the booth water).

In one aspect of the invention, the collection device comprises:
A concentration / separation device for separating the first booth water collecting the water-based paint into a concentration part having an increased water-based paint concentration and a remaining part having a reduced water-based paint concentration;
It further includes a concentrating tank connected to the concentrating / separating device so as to store the concentrating portion obtained and to supply the concentrating / separating device. Thereby, the collected water-based paint can be circulated and concentrated to a desired concentration and reused. Moreover, the remainder (for example, filtrate) in which the aqueous coating material concentration decreased can be used again as the first booth water.

  In the present invention, the “water-based paint concentration” means, more strictly, the concentration of the nonvolatile content of the water-based paint. Generally, a cross-flow filter, preferably an ultrafilter, can be used for the concentration and separation device. The non-volatile component that is a component of the water-based paint has a molecular weight larger than the molecular weight cut off of the filter (filter material), so it remains upstream without passing through the filter. On the other hand, a component having a molecular weight smaller than this molecular weight cut-off is Since it moves to the filtrate side through the filter, the non-volatile content contained in the water-based paint can thereby be concentrated. A tank different from the first recovery tank is used as the concentration tank.

  Further, a plurality of sets each including a concentration / separation device and a concentration tank may be prepared, and the set to be used may be switched according to the color of the water-based paint. According to this, it is possible to cope with multiple colors for reuse of water-based paint. When the color change is reused, the cleaning performance of the booth is particularly important. However, according to the present invention, the first booth water, which is the cleaning liquid, can reach the contaminated portion, and the liquid pool of the cleaning liquid is not formed. Therefore, it can be suitably used for color change reuse.

  However, the present invention is not limited to this, and the first booth water recovered in the first recovery tank may be discarded after being subjected to a general wastewater treatment method such as sedimentation separation and flotation separation as necessary. .

In one aspect of the present invention, the collection device comprises:
A second flow path through which the gas that has passed through the first flow path flows;
At least one of a filler (or filter) and a baffle plate (or eliminator plate) disposed in the second flow path;
And a second recovery tank for recovering the second booth water supplied into the second flow path, whereby the aqueous paint remaining in the form of mist in the gas that has passed through the first flow path is transferred to the second booth. It may be collected in water. Hereinafter, in the present specification, the second flow path and the second recovery unit are also referred to as a secondary collection unit.

  According to the above aspect, the gas that has passed through the first flow path passes through the filler and / or collides with the baffle plate, the aqueous paint mist remaining in the gas is separated, and the aqueous paint is submerged in the second booth water. And can be recovered in the second recovery tank. Thereby, water-based paint mist can be collect | recovered by 2 steps | paragraphs of a primary collection part and a secondary collection part, and high collection efficiency is realizable as a whole. Furthermore, the process for the first booth water recovered in the first recovery tank and the second booth water recovered in the second recovery tank can be appropriately selected individually. For example, the former may be used for reusing water-based paints and the latter may be discarded. In addition, since most of the aqueous paint mist can be collected and recovered in the first booth water as described above, the aqueous paint concentration of the second booth water can be lowered and can be cleaned by circulating the second booth water. Therefore, the maintenance frequency of the second flow path can be reduced. Such a coating booth can be used suitably when reusing and changing colors because the entire booth can be easily cleaned. In addition, the secondary collection unit may be arranged adjacent to the primary collection unit or may be arranged separately, and can be designed with any arrangement.

  For the filler (or filter) and baffle plate (or elimine plate), any suitable filler that can be commonly used for gas-liquid separation can be used.

According to another aspect of the present invention, a painting booth used for painting an article to be coated with a water-based paint,
A painting room for spraying water-based paint on the object,
The first booth water is supplied into the coating chamber, and the gas containing the mist-like water-based paint in the coating chamber and the supplied first booth water communicate with the coating chamber so as to flow to the first flow path. A paint booth comprising a collection device is provided.

  An object to be coated by the painting booth of the present invention is, for example, an article (for example, a part such as an automobile and other general industrial products) that is automatically conveyed while being hung up, generally called a workpiece. Alternatively, it may be a larger article (for example, an automobile body) that is not suspended and conveyed. The water-based paint may be supplied as a water curtain behind the object to be coated, depending on the object to be painted and the spray direction, or a water screen (or water filled, water wall) below the object to be coated. Alternatively, it may be understood as a water tunnel or the like, but may be supplied as a water screen for the sake of convenience in this specification.

  According to the present invention, there is provided a collection device capable of effectively reducing and preferably preventing foaming and collecting paint mist even when spray coating is performed using an aqueous paint. Furthermore, the collection device of the present invention has higher cleaning performance, less maintenance frequency, and lower noise than conventional collection devices. Moreover, according to this invention, the coating booth provided with such a collection apparatus is also provided.

  Hereinafter, a collection device and a painting booth in some embodiments of the present invention will be described with reference to the drawings. In the description of these embodiments, the same reference numerals are used for the same members, and the same description applies unless otherwise specified.

(Embodiment 1)
The present embodiment relates to a collection device and a painting booth including the same.

  A coating booth 30 according to the present embodiment shown in FIG. 1A includes a coating chamber 1 for spraying a water-based paint 9 onto a work 5 that is an object to be coated, and a collection device 29 for collecting the water-based paint 9. With. The collection device 29 according to this embodiment includes a primary collection unit 10 formed integrally with the coating chamber 1 and a secondary collection unit 20 communicating with the primary collection unit 10.

  An air flow (indicated by an arrow in the figure) is formed in the painting booth 30 by the blower fan 3 arranged in the painting chamber 1 and the exhaust fan 27 arranged in the secondary collection unit 20. The gas atmosphere is forcibly exhausted.

  A nozzle 7 for spraying a water-based paint is provided in the painting chamber 1. The first booth water 12 is supplied into the painting chamber 1, but a part of the water flows from the riser 18 or overflows along the flat plate, and the water curtain 11 located behind the work 5 with respect to the nozzle 7. Supplied in form. The coating chamber 1 communicates with the primary collection unit 10 so that the gas inside the coating chamber 1 and the supplied first booth water 12 flow along the inclined wall 13 to the first flow path 15.

  The primary collection unit 10 includes a first flow path 15 and a first recovery tank 17 that recovers the first booth water 12 that has passed through the first flow path 15. As shown in FIG. 1B, the first flow path 15 has at least one bent portion 15a. In addition, although the airflow direction is bent 3 times in FIG.1 (b), it is not limited to this.

  The contact angle of the first booth water 12 with respect to the inner wall surface of the first flow path 15 is, for example, within about 60 ° (0-60 °), and preferably within about 30 ° (0-30 °). The first booth water 12 preferably has a small surface tension, and the first booth water 12 recovered in the first recovery tank 17 is supplied into the coating chamber 1 as indicated by a dotted line in FIG. Use it cyclically. The first booth water 12 contains a suitable amount of a hydrophilic solvent derived from an aqueous paint, such as diethylene glycol monobutyl ether (BDG), in water, and has a low surface tension. On the other hand, the inner wall surface of the first flow path 15 may be made of a material such as stainless steel if the surface tension of the first booth water 12 is small. For example, the surface is coated with a hydrophilizing agent made of silicate. More preferably, it consists of

  As shown in FIG. 2, the inclination angle of the inner wall surface (including the bent portion 15a) of the first flow path 15 with respect to the horizontal plane is, for example, about 15 to 165 °, preferably about 15 °, depending on the size of the contact angle. It shall be in the range of 30-150 degrees. If the inclination angle is too small, the first booth water 12 becomes difficult to flow, and the aqueous paint contained therein may adhere to the inner wall surface. On the other hand, if the inclination angle is too large, the first booth water 12 drops from the inner wall surface of the first flow path 15 and a liquid film cannot be formed.

  The inner wall surface of the first flow path 15 is preferably smooth without any irregularities. In addition, the bent portion of the first flow path 15 is preferably curved rather than the inner wall surface being refracted sharply.

  Referring to FIGS. 3A to 3E, the inner wall surface that opposes the vertical cross section of the first flow path 15 leaves a gap through which gas can flow as shown by a double arrow in the figure, and the first booth water. As long as they are covered with 12 liquid films, they may be substantially parallel to each other (FIG. 3 (a)) or may be expanded in the flow direction indicated by a single arrow in the figure (FIGS. 3 (b) and (d). )), It may be narrowed (FIGS. 3C and 3E).

  In the horizontal cross section of the first flow path 15, the inner wall surface may have an arbitrary shape, for example, a slit shape, a circular shape, or the like, and may have a shape such as a prism or a cylinder as a whole. Further, one or more such first flow paths 15 may be provided.

  Referring to FIG. 1A, the secondary collection unit 20 is supplied for cleaning the filler 23 in the second channel 25 having the filler 23 therein and the second channel 25. And a second recovery tank 21 for recovering the second booth water 22. The second flow path 25 communicates with the first flow path 15 through the communication path 19 so that the gas that has passed through the first flow path 15 flows. The second booth water 22 collected in the second collection tank 21 is supplied into the second flow path 25 and circulated for use as shown by the dotted line in FIG.

  As the filler (or filter), a material having both mist collecting ability and cleaning ability is used. In particular, in order to provide cleaning properties, it is preferable to have a simple structure that is made of a material resistant to both booth water and paint and is difficult for the cleaning liquid (booth water) to enter (no bag portion).

  Next, operation | movement and an effect | action of the coating booth 30 provided with the collection apparatus 29 of this embodiment are demonstrated.

  First, the work 5 that is the object to be coated is suspended and conveyed into the coating chamber 1 as shown in FIG. 1A, for example, and the air flow is generated by the blower fan 3 and the exhaust fan 27, and the nozzle 7 The workpiece 5 is painted by spraying the water-based paint 9 toward the workpiece 5.

  During the painting, the first booth water 12 is supplied into the painting chamber 1 by, for example, a pump in order to clean the inside of the painting chamber 1 (supplied from three places in FIG. 1). A part of the first booth water 12 flows down along the wall to form the water curtain 11. The supplied first booth water 12 enters the first flow path 15 through the inclined wall 13 and flows through the first flow path 15 together with the gas while forming a liquid film covering the inner wall surface of the first flow path 15. The first booth water 12 is always supplied during the painting.

For example, when the first booth water 12 is a liquid having a water: BDG weight ratio of about 95: 5, the water curtain width is about 40 liters / minute and the airflow passing through the water curtain is about 70 m ³ / minute. (In either case, the standard state conversion at 20 ° C. and 0.1 MPa, the same shall apply hereinafter).

  Of the water-based paint sprayed from the nozzle 7, most of the water-based paint not applied to the work 5 reaches the water curtain 11 and is collected in the first booth water 12. In addition, although water-based paint may exist in a mist form in the gas in the coating chamber 1, such water-based paint mist flows along an air current, and a part of the first booth water 12 flows on the inclined wall 13. Can be collected inside. Furthermore, as shown in FIG. 1B, when the gas flows through the first flow path 15, the aqueous paint mist 9 a contained in the gas can be collected in the first booth water 12. This is because the direction of the airflow is changed by the bent portion 15 a, whereas the water-based paint mist 9 a flows away from the airflow because it is affected by the inertial force, and covers the inner wall surface of the first flow path 15. It is because it collides with or contacts the first booth water 12.

  The first booth water 12 that has collected the water-based paint in this manner is recovered in the first recovery tank 17. The recovered first booth water 12 may be used in a circulating manner, and may be discarded after being subjected to a general wastewater treatment method such as sedimentation separation and flotation separation, if necessary.

  On the other hand, the gas discharged from the first flow path 15 enters the secondary collection unit 20 through the communication path 19 and flows up through the second flow path 25. At this time, the gas can include the water-based paint mist 9 a that could not be collected by the primary collection unit 10, but can be captured by the filler 23. The gas that has passed through the filler 23 is preferably substantially free of water-based paint mist and discharged to the outside of the painting booth 30.

  The second booth water 22 is supplied into the second flow path 25 in order to clean the filler 23. As a result, the aqueous paint mist captured by the filler 23 is collected in the second booth water 22. In the present embodiment, the second booth water 22 is supplied while painting is not being performed (when the exhaust fan 27 is stopped).

  The second booth water 22 that has collected the water-based paint mist in this manner is recovered in the second recovery tank 21. The recovered second booth water 22 is recycled. Further, the concentration of water-based paints is controlled by a wastewater treatment method such as sedimentation separation, flotation separation, and ultrafiltration to control the aqueous paint concentration to be low (for example, about 5% or less), and the paint obtained by the concentration operation may be discarded. . As a result, since the increase in the aqueous paint concentration is small, the load on the wastewater treatment apparatus can be reduced.

  According to the collection device 29 and the coating booth 30 of the present embodiment as described above, since the first booth water 12 (and the second booth water 22) is not vigorously mixed with gas, foaming is effectively suppressed and preferably The water-based paint can be collected in the booth water. Thus, when the collected first booth water 12 (and second booth water 22) is subjected to a general wastewater treatment method such as sedimentation separation and flotation separation, it is necessary to add a large amount of antifoaming agent as in the past. The amount of antifoaming agent can be reduced and preferably made unnecessary.

  Further, the water-based paint can be quickly collected by the first booth water 12 without being fixed to the inner wall surface, and the first flow path can be kept relatively clean. As a result, the interior of the coating chamber 1 and the inside of the first flow path 15 can be cleaned with a smaller amount of cleaning water (or cleaning agent) to sufficiently remove the water-based paint. Furthermore, since the riser 18 is not disposed in the painting chamber 1, the water-based paint does not adhere to the riser itself. Therefore, the frequency of the maintenance of the primary collection part 10 and the coating chamber 1 can be reduced.

  Moreover, the 1st collection tank 17 is smaller than the booth water tank 73 in the conventional painting booth 60 demonstrated with reference to FIG. For example, when a booth water tank 73 having a capacity of about 100 to 300 liters is conventionally used per 1 m of the water curtain width, the capacity of the first recovery tank 17 may be about 20 to 50 liters according to the present embodiment.

  In addition, the pressure loss while passing through the first flow path 15 (and the second flow path 25) is greater than the pressure loss used to pass the gas through the water curtain 71 at a sufficient wind speed in the conventional painting booth 60. Therefore, noise can be further reduced.

  Furthermore, in the collection device 29 and the coating booth 30 of this embodiment, since the secondary collection unit 20 is provided in addition to the primary collection unit 10, the aqueous paint mist can be collected in two stages. Even when the water-based paint mist cannot be sufficiently collected in the first booth water 12, it is possible to achieve high collection efficiency as a whole by collecting it in the second booth water 22.

  Further, since the second booth water 22 is recovered in the second recovery tank 21 separate from the first recovery tank 17, and the filler 23 is washed using this, the single booth water 90 as in the conventional coating booth 90 is used. The concentration of the aqueous paint in the second booth water is lower than when a part of the booth water in the booth tank 73 is used to wash the filter 79 and the baffle plate 77, and concentration operations such as sedimentation separation, flotation separation and ultrafiltration are performed. It is possible to easily control the low concentration with a paint recovery apparatus that performs the above. Thereby, for example, conventionally, the maintenance of the exhaust passage 81 has been performed four times per year, but according to the present embodiment, the maintenance of the second flow path 25 can be reduced to once or less per year.

  In addition, the secondary collection unit 20 may be arranged adjacent to the primary collection unit 10 and may be directly connected without the communication unit 19 or may be arranged apart by appropriately routing the communication channel 19. Therefore, the degree of freedom in design is high and the space can be used effectively.

(Embodiment 2)
In the present embodiment, the collection of the first booth water and the second booth water is modified in the collection device and the painting booth of the first embodiment, and further, multicolor support is possible.

  The painting booth 30 ′ of this embodiment shown in FIG. 4 has a plurality of first recovery tanks 17 ′ that are used in accordance with the color of the water-based paint (in the figure, for A-color, B-color, and C-color water-based paints). 3) and a second recovery tank 21 'that is not used for switching.

  Corresponding to the plurality of first recovery tanks 17 ′, a first set of a concentration tank 31, an ultrafilter UF, and a filtrate tank 33 are provided (concentration unit for reuse). The UF is a concentration / separation device that separates the first booth water in which the water-based paint is collected into a concentrated part in which the aqueous paint concentration is increased and a remaining part (filtrate) in which the aqueous paint concentration is reduced. In each first set, the concentration tank 31 is connected to the first recovery tank 17 ′ so that the first booth water recovered in the first recovery tank 17 ′ is transferred to the concentration tank 31, and by the UF The obtained concentrated part is stored in the tank and connected to the UF so as to be supplied back to the UF. On the other hand, the filtrate tank 33 is connected to the UF so as to store the remainder (filtrate) obtained by the UF. In addition, a second set of the concentration tank 35, the ultrafilter UF, and the filtrate tank 37 is provided for the second recovery tank 21 '(concentration unit for disposal), and is configured in the same manner as the first set.

  In the present embodiment, for example, the first booth in which the A color water-based paint is applied in the same manner as in the first embodiment and the A color water-based paint in the first collection tank 17 ′ is collected after the A color paint is completed. Water is sent to the concentration tank 31 as shown by the one-dot chain line in FIG. Thereafter, the first booth water is allowed to flow from the concentration tank 31 to the UF to separate the A color water-based paint concentration into a concentration part and a filtrate. The concentration part is returned to the concentration tank 31 and the filtrate is sent to the filtrate tank 33. This operation is carried out continuously, and the solution is circulated and concentrated until the desired aqueous paint concentration is obtained in the concentration section. The concentrated part thus obtained is used for reuse (recycling) of the water-based paint. On the other hand, the obtained filtrate may be recycled as the first booth water 12 by returning it to the middle of the first recovery tank 17 ′ or its circulation and use line (shown by a dotted line in the figure).

  In the present embodiment, the first recovery tank 17 'and the concentration tank 31 are provided separately, but they may be a common tank. When using the first recovery tank 17 ′ as the concentration tank 31, when the first recovery tank 17 ′ is used as the concentrating tank, the first recovery tank 17 ′ is separated from the primary collection part and circulated and concentrated in another place without being disconnected. It may be circulated and concentrated on the spot.

  The circulation concentration of the A-color water-based paint can be performed while the paint chamber 1 is not applied, or while the other color (for example, B color) water-based paint is being applied.

  After the application with the A-color water-based paint is completed, the color is changed and the paint is applied with the B-color and C-color water-based paints. The painting and circulation concentration and reuse in the case of the B-color and C-color water-based paints can be performed in the same manner as in the case of the A-color water-based paint.

  Then, the second booth water 22 is supplied into the second flow path 25 in order to clean the filler 23. As a result, the aqueous paint mist captured by the filler 23 is collected in the second booth water 22. The second booth water 22 may be supplied while painting is not being performed (for example, at the end of painting of each color, at a break, or at the time of color change).

  On the other hand, since the second recovery tank 21 ′ is used regardless of the color of the water-based paint, the second booth water 22 recovered in the second recovery tank 21 ′ has a plurality of colors (A color, B color, and C color). It exhibits a mixed color in which water-based paint is mixed. While the coating is stopped, the second booth water in which the water-based paints of a plurality of colors in the second collection tank 21 'are collected is sent to the concentration tank 35 as shown by a one-dot chain line in FIG. Thereafter, the second booth water is allowed to flow from the concentration tank 35 to the UF, the concentrated portion where the aqueous paint concentration has increased is returned to the concentration tank 35, and the filtrate is sent to the filtrate tank 37. This operation is continuously carried out to circulate and concentrate. The concentrated part thus obtained may be discarded as it is. On the other hand, the obtained filtrate may be discarded as it is, or may be recycled as the second booth water 22 by returning it to the middle of the second recovery tank 21 'or its circulation and use line (shown by a dotted line in the figure).

  According to the collection device and the coating booth 30 ′ of this embodiment, the water-based paint can be reused by the reuse concentrating unit. In the present embodiment, foaming can be effectively suppressed by the same action as in Embodiment 1 to eliminate the addition of an antifoaming agent. Not included. Moreover, since the secondary collection part is provided in addition to the primary collection part as in the first embodiment, the paint scum is not mixed into the collection tank from the exhaust path as in the prior art, and can be reused. A suitable first booth water can be recovered. It should be noted that these effects are obtained not only in the case of multiple colors but also in the case of a single color (for example, only A color).

  Further, according to the present embodiment, the first booth water that collects the water-based paint can be collected and reused for each color even when color change is performed. In the present embodiment, when the color is changed, the coating chamber 1 and the first flow path 15 are washed with a small amount of cleaning water (or cleaning agent) by the same operation as in the first embodiment, so that the water-based paint of the previous color is obtained. Can be removed sufficiently, so that the color change time can be shortened. Conventionally, it takes about 15 minutes for cleaning for color change. However, according to this embodiment, it can be sufficiently cleaned in about 2 to 5 minutes, for example.

  Furthermore, since the first recovery tank 17 ′ can be made compact by reducing the amount of washing water, a larger number of first recovery tanks 17 ′ can be arranged in the same space, and the water-based paint having a larger number of colors can be accommodated. Can do. In a space where only one color or at most two colors can be handled in a conventional painting booth, according to the present embodiment, up to about ten colors can be handled. In the present embodiment, the case of three colors has been described as an example, but the present invention is not limited to this.

(Embodiment 3)
In this embodiment, the collection device and the painting booth according to the second embodiment are modified so that an automobile body is an object to be coated instead of a workpiece.

  The painting booth 30 ″ of this embodiment shown in FIG. 5 includes a painting chamber 1 ′ for painting the automobile body 5 ′, and the first booth water 12 is a water screen 11 ′ located below the automobile body 5 ′. Etc. are supplied into the painting chamber 1 ′.

  According to the collection device and the coating booth 30 ″ of the present embodiment, the water-based paint can be reused by the same action as that of the second embodiment. When water-based paint is used in a conventional wet paint booth for automobile bodies (see, for example, Patent Document 1), in addition to the problem of foaming, it has a very large capacity, a total capacity of about 50 to 150 tons, and a water curtain width of 1 m. Since it was necessary to use a booth water tank having a capacity of about 600 to 3000 liters per unit, it was difficult to reuse the water-based paint. On the other hand, according to the present embodiment, the first recovery tank 17 ′ can be made compact. For example, the capacity of the first recovery tank 17 ′ per 1 m of the width of the water curtain may be about 100 to 300 liters. Reuse of paint can be carried out at a practical level.

  In addition, although the two-stage collection apparatus provided with both the primary collection part and the secondary collection part was demonstrated in Embodiment 1-3, that a secondary collection part is not essential in the collection apparatus of this invention. Please keep in mind.

  In this example, the influence of the contact angle and the inclination angle on the liquid film forming property and the cleaning property was examined.

  First, booth water was placed on a sample made of the same material as the inner wall surface of the first flow path, and the contact angle was examined. Booth water is a water-based paint added to water and contains a hydrophilic organic solvent (diethylene glycol monobutyl ether (BDG)) derived from the water-based paint. The combinations showing the contact angles in Table 1 were selected by varying the amount of the inner wall material and the amount of water-based paint (more specifically, hydrophilic solvent) added.

  Then, the first booth water flows down along the sample of the inner wall surface of the first flow path arranged at a predetermined inclination angle (see FIG. 2), and the membrane breaks and / or the liquid dripping occurs. Please observe visually. At this time, the flow rate of the booth water was about 7 liters / minute per 0.3 m of the sample width.

  The evaluation criteria for the liquid film formation are: ○ when the film breakage and / or dripping of the liquid did not occur in the descending order of evaluation, △ when it occurred slightly but acceptable, and when it occurred clearly X.

  Further, booth water was circulated in a circulating manner, and then, it was visually observed whether or not the water-based paint adhered to the inner wall surface sample of the first flow path. At this time, the flow rate of the booth water was the same as described above.

  The evaluation criteria for detergency were ◯ when the water-based paint did not adhere in the descending order of evaluation, △ when it was slightly occurring but acceptable, and x when it was apparent.

  Then, the evaluation results of the liquid film forming property and the cleaning property were integrated, and the lower of the two evaluations was adopted. The results are shown in Table 1.

  From the viewpoints of liquid film formability and cleanability, it was found that the contact angle and tilt angle conditions indicated by ○ in Table 1 are preferable. For example, when stainless steel is coated with a hydrophilizing agent consisting of silicate on the inner wall surface and the booth water is a mixed liquid with a water: BDG weight ratio of 95: 5, the contact angle is about 20 °, which is acceptable. The range of tilt angles was about 10-170 °, preferably about 30-150 °. On the other hand, for example, when the inner wall surface is made of stainless steel and the booth water is simply water, the contact angle is about 90 °, and the allowable inclination angle range is about 10 to 120 °, preferably 15 to 90 °. It was. In the latter case, it is necessary to relatively increase the flow rate of the first booth water to the first flow path in order to prevent the membrane from being interrupted. You should consider what can happen.

  In the present embodiment, when the first booth water flows while forming a liquid film covering the inner wall surface of the first flow path, the inclination angle of the inner wall surface of the first flow path and the inner wall surface and the first booth. Although the contact angle with water has been described, the inclination angle greater than 90 ° among the results of the present example is applicable even when the second booth water flows while forming a liquid film covering the inclined lower surface of the baffle plate. Maru. In the latter case, it should be noted that the inclination angle is preferably somewhat larger than 90 °, for example, 120 ° or more, from the viewpoint of the apparatus configuration, apart from the liquid film forming property and the cleaning property.

  In this example, a test machine in the painting booth was operated to examine the collection property, cleaning property, and foaming property.

  First, the coating booth 30 ′ shown in FIG. 4 described above in Embodiment 2 was configured as an implementation test machine having a water curtain width of about 1.5 m. In this test machine, a filter (not shown) was provided above the filler 23 in the second flow path 25 in order to completely remove the aqueous paint mist from the gas.

Then, the water-based paint 9 was sprayed for about 30 minutes without circulating the work 5 while circulating the first booth water collected in the first collection tank 17 ′, assuming the coating with the water-based paint 9. At this time, an air spray gun was used for the nozzle 9, the air pressure was about 0.2 MPa, and the water-based paint 9 was sprayed at about 2 to ³ g / m ³ . Moreover, the exhaust air volume per 1 m of water curtain width was set to about 70 m ³ / min. The aqueous paint mist concentration in the gas exhausted through the filter and the exhaust fan 27 was about 2 to ³ g / m ³ . The concentration of the non-volatile content of the water-based paint in the first booth water was about 2% by weight before the application, but increased to about 5% immediately after the application. During the coating, the second booth water was not supplied into the second flow path 25.

  For comparison, a conventional painting booth 60 ′ as shown in FIG. 7 is configured as a comparative test machine having a water curtain width of about 0.5 m, and using this comparative test machine, conditions similar to those of the test machine are shown. The painting was carried out. At this time, the wind speed of the airflow when passing through the water curtain 71 was about 15 m / s. During the painting, booth water was not supplied into the exhaust passage 81.

(Catchability)
After the completion of coating, the water-based paint collecting property due to the effects of the primary collecting part and the secondary collecting part was evaluated.

  First, the solid content weight of the water-based paint used for coating in the test machine and the comparative test machine was determined by measuring the amount of water-based paint reduced in a paint tank (not shown).

  In the case of using the test machine, the concentration of non-volatile content in the first booth water in the first recovery tank 17 ′ is compared before and after the coating is performed, and from the increase, the water paint collected in the first booth water The solid content weight was determined. In addition, it can be considered that the non-volatile content is substantially equal to the solid content. Moreover, the filter (without washing | cleaning) after application | coating execution was dried, the weight was measured, this was compared with the weight before application | coating execution, and the increase was made into the solid content weight of the water-based paint captured by the filter.

And the collection rate of the 1st booth water and the filter was calculated | required by the following formula (I), respectively.

  The collection rate in the first booth water was 80%, and the collection rate in the filter was 0.3%. It may be considered that the collection rate by the primary collection unit (the first flow path including the bent portion) is the same as the collection rate of 80% in the first booth water. The collection rate by the secondary collection part (filler 23) is that the gas exhausted from the exhaust fan 27 does not contain water-based paint mist, and all the water-based paints are collected in the painting booth. Therefore, it is estimated as 19.8% obtained by subtracting the collection rate in the first booth water (80%) and the collection rate in the filter (0.2%) from 100%.

  In the case of using a comparative test machine, the filter after coating (not washed) is dried and weighed, compared with the weight before coating, and the increased amount is captured by the filter. The solid content weight of the paint was used.

  And when the collection rate of the filter was calculated | required by said formula (II), it was 0.9%. For the same reason as above, the total collection rate by the water curtain, centrifuge plate, and baffle plate is estimated as 99.1% minus 100% collection rate in booth water (0.9%). .

  From the above results, in the test machine, it was confirmed that most of the water-based paint contained in the gas (80% in this example) can be collected by the primary collection unit, and the primary collection unit and If the collection rate by the secondary collection part is integrated (99.8% in this embodiment), more water-based paint than in the case of the comparative test machine water curtain, centrifugal plate and baffle plate (99.1%) It was found that can be collected.

(Cleanability)
After the coating was completed, the coating chamber was washed with the filtrate, and the cleaning property was evaluated by examining the change with time of the non-volatile concentration in the washing solution during the filtrate washing.

  In the case of the implementation test machine, the filtrate prepared separately was supplied into the coating chamber 1 through the circulation line of the first booth water 12 (shown by a dotted line in the figure) and washed with the filtrate. The liquid after washing flowing into the first recovery tank 17 ′ through the first flow path 15 was sampled at a predetermined time from the start of washing (filtrate supply), and the concentration of nonvolatile content in each sample was measured. The results are shown in FIG.

  In the case of the comparative test machine, the separately prepared filtrate was supplied into the coating chamber 61 from the riser 78 through the booth water circulation line (shown by a dotted line in the figure) and washed with the filtrate. During the washing of the filtrate, the non-volatile content in each sample was measured in the same manner as described above. The results are shown in FIG.

  Referring to FIG. 6, in the test machine, the concentration of non-volatile content was about 150 ppm by weight after 1 minute and 100 ppm by weight after 2 minutes. On the other hand, the comparative test machine required a time longer than 6 minutes in order to make the nonvolatile content concentration 500% by weight or less, and required a large amount of cleaning liquid according to the cleaning time. From this result, it was confirmed that the test machine had higher cleaning properties than the comparative test machine and could be sufficiently cleaned with a smaller amount of cleaning liquid (filtrate).

(Foaming)
During the coating process while circulating the booth water, the foaming degree was examined to evaluate the foamability. No antifoaming agent was used throughout the painting and filtrate washing operations.

In the case of the test machine, the volume of the foam and the booth water existing in the tank is examined for the first recovery tank 17 ′ and the booth water tank 73 ′ in the case of the comparative test machine. Asked.

  In the test machine, the foaming rate was 5% or less, while in the comparative test machine, the foaming rate was 30% or more. From this result, it was confirmed that when the test machine was used, the foaming rate was sufficiently smaller than when the comparative test machine was used, and foaming could be effectively suppressed.

FIG. 1A is a schematic cross-sectional view of a painting booth equipped with a collection device according to one embodiment of the present invention, and FIG. 1B is a partially enlarged schematic cross-sectional view of the collection device of FIG. It is a figure explaining the inclination-angle of the inner wall face of the 1st flow path in embodiment of FIG. FIGS. 3A to 3E are diagrams showing a modification of the first flow path in the embodiment of FIG. It is a schematic sectional drawing of the coating booth provided with the collection apparatus in another embodiment of this invention. It is a schematic sectional drawing of the coating booth provided with the collection apparatus in another embodiment of this invention. It is a graph for evaluating the washing | cleaning property of the implementation test machine and comparative test machine in Example 2 of this invention. FIG. 7A is a schematic sectional view of a painting booth equipped with a conventional collecting device, and FIG. 7B is a partially enlarged schematic sectional view of the collecting device of FIG.

Explanation of symbols

1, 1 'painting chamber 3 blower fan 5 work (object to be coated)
5 'Auto Body (Coating)
7 Nozzle 9 Water-based paint 9a Water-based paint mist 10 Primary collection part 11 Water curtain 11 'Water screen 12 First booth water 13 Inclined wall 15 First flow path 15a Bent part 17, 17' First collection tank 19 Communication path 20 Secondary collection unit 21, 21 ′ Second recovery tank 22 Second booth water 23 Filler 25 Second flow path 27 Exhaust fan 29 Collection device 30, 30 ′, 30 ″ Coating booth 31, 35 Concentration tank 33, 37 Filtrate tank

Claims (7)

A collection device for collecting water-based paint,
A first flow path through which a gas containing a mist-like aqueous paint and a first booth water flow;
A first recovery tank that recovers the first booth water that has passed through the first flow path, the first flow path has at least one bent portion, and the first booth water covers the inner wall surface of the first flow path. A collector that flows through the first flow path together with the gas while forming a liquid film, thereby collecting the aqueous paint contained in the gas in a mist form in the first booth water.   The collection device according to claim 1 whose contact angle of the 1st booth water with respect to the inner wall surface of the 1st channel is less than 60 degrees.   The collection device according to claim 1 or 2, wherein the inner wall surface of the first flow path is inclined at an angle of 15 to 165 ° with respect to a horizontal plane. A second flow path through which the gas that has passed through the first flow path flows;
At least one of a filler and a baffle arranged in the second flow path;
And a second recovery tank for recovering the second booth water supplied into the second flow path, whereby the aqueous paint remaining in the mist form in the gas that has passed through the first flow path is transferred to the second booth. The collection device according to claim 1, which is collected in water. A concentration / separation device for separating the first booth water collecting the water-based paint into a concentration part having an increased water-based paint concentration and a remaining part having a reduced water-based paint concentration;
The collection device according to any one of claims 1 to 4, further comprising a concentration tank connected to the concentration / separation device so as to store the obtained concentration unit and supply the concentration unit to the concentration / separation device.   The collection device according to claim 5, wherein a plurality of sets including the concentration separation device and the concentration tank are used by switching according to the color of the aqueous paint. A painting booth used to paint an object with water-based paint,
A painting room for spraying water-based paint on the object,
The first booth water is supplied into the coating chamber, and the gas containing the mist-like water-based paint in the coating chamber and the supplied first booth water are communicated with the coating chamber so as to flow through the first flow path. A painting booth comprising the collection device according to any one of the above.

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