JP4554100B2 - Control method of solvent concentration in booth circulating water in water-based paint recycling system - Google Patents

Description

[0001]
【Definition of terms】
In the present invention, the “solvent” includes both water-based paints and volatile solvents (excluding water) that are usually used in water-based paint recycling systems.
[0002]
BACKGROUND OF THE INVENTION
The present invention relates to an aqueous paint recycling system in which a paint (overspray paint) that has not adhered to an object to be coated is collected with an aqueous carrier at the time of application of the aqueous paint, is reconditioned and reused. The present invention relates to a solvent concentration management method for adjusting the concentration of a solvent contained in a carrier.
[0003]
[Prior art]
Since water-based paints are mainly composed of water, they are less hazardous to the human body in the paint environment and easier to handle than solvent-based paints. Unpainted paint (overspray paint) can be recovered with aqueous solvent, filtered and concentrated, and then the paint composition can be adjusted again and reused (recycled) as an aqueous paint. Recycling has the advantage that it can also be achieved. In recent years, water-based paints have attracted attention for such advantages, and are frequently used for industrial coatings such as automobile bodies and home appliances.
[0004]
FIG. 4 shows a conceptual diagram of a recycling system for painting, collecting, and reusing a water-based paint. In FIG. 4, the water-based paint 20 is sprayed from the painting gun 2 in the water curtain type painting booth 1 in order to coat the article 50, and the overspray paint 4 generated at that time is mainly composed of water. It is collected by the water curtain 3 and temporarily stored in the booth circulating water tank 5 as the booth circulating water 6. The booth circulating water 6 is repeatedly used for the water curtain 3, is transferred to the settling tank 15 at a desired time, temporarily stored, and then sent to the concentration tank 7 for the separation / concentration process (in FIG. 4, Booth circulating water 8 '). In the separation / concentration step, the booth circulating water 6 from the concentration tank 7 is usually separated into a paint component and a filtrate 11 using an ultrafiltration device 9. The paint components are again returned to the concentration tank, while the filtrate 11 is sent to the filtrate tank 10 for storage. The paint component is further separated and concentrated by the ultrafiltration device 9 to obtain a concentrated paint 13, which is transferred to the concentrated paint tank 12 and stored. After being taken out and adjusted when necessary, it is sent to the painting gun 2 and reused for painting. On the other hand, the filtrate 11 is transferred to the booth circulating water tank 5 and reused as the booth circulating water 6. FIG. 4 shows a recycling system including one painting booth. However, since the number of painting booths 5 can be changed as desired, a plurality of painting booths 5 may exist.
[0005]
Here, when the overspray paint 4 is recovered using the booth circulating water 6 composed of 100% water, the solid content of the paint is granulated without being sufficiently dispersed and held or dissolved in the booth circulating water 6, and the water curtain 3 Water splashing may be worsened and contamination may occur (decrease in stability of booth circulating water). This is considered due to the low solvent concentration in the booth circulating water 6. In order to avoid such a problem, a solvent such as a volatile hydrophilic solvent is added to the booth circulating water 6 to increase the solvent concentration in the booth circulating water to some extent.
[0006]
However, the solvent concentration in the booth circulating water 6 is gradually increased depending on the presence of various solvents remaining in the recovered overspray paint 4 in addition to the evaporation of water by repeated use in the painting booth 1. Will increase. Further, in the washing of the painting booth 1 performed when the spray painting is stopped, since this washing is performed with the filtrate, a solvent component contained in the filtrate is newly added, and as a result, the solvent concentration in the booth circulating water increases. As a result, if the solvent concentration in the booth circulating water becomes too high, there arises a problem that the drying property of the concentrated paint 13 obtained from the subsequent separation / concentration step is deteriorated.
[0007]
Therefore, it is necessary to manage the concentration of the solvent contained in the booth circulating water so that it is maintained within an appropriate range that is neither too low nor too high.
[0008]
Conventionally, the solvent concentration in the booth circulating water is moved to the separation / concentration process directly from the booth circulating water tank 5 after the recycling system has been operated for a certain period and after spray painting is stopped, and is adjusted or settling there. When passing through the tank 15, the composition and the amount of liquid are checked in the settling tank 15. Such adjustment of the solvent concentration can be performed without any problem when there is only one painting booth, but it becomes more difficult as the number of painting booths increases.
As one factor that makes it difficult to adjust the solvent concentration in the booth circulating water generated in a plurality of coating booths, it is conceivable that the operation conditions such as the operation time and the solvent concentration of the plurality of coating booths are different. In this case, for each painting booth, the initial supply amount of the circulating water of the booth, the evaporation amount of water until after the spray coating is stopped, the amount of solvent in the captured over paint, and the like must be separately recorded as needed. Such a recording operation increases in proportion to the number of coating booths and can be more complicated, which may hinder the operation of the recycling system.
[0009]
[Problems to be solved by the invention]
It is an object of the present invention to provide a booth circulating water that is circulated and used in a recycling system in order to obtain an optimum regenerated paint by operating stably for a long time even in a recycling system having a large number of coating booths. The object is to provide a method for more easily and efficiently managing the solvent concentration.
[0010]
[Means for Solving the Problems]
The present inventors have provided a painting booth arranged in the recycling system by replenishing the amount of water lost due to evaporation before subjecting the circulating water to the separation / concentration process. The present invention has been completed by finding a method capable of more easily and appropriately managing the solvent concentration in the booth circulating water without depending on the number of the above.
Therefore, according to the present invention, the water-based paint is sprayed separately in two or more water curtain type painting booths, and the overspray paint that has not been applied to the object to be coated is placed in each painting booth by the booth circulating water. After collecting each in the circulating water tank, the booth circulating water is transferred to the concentration tank, separated and concentrated by the ultrafiltration device, stored as a concentrated paint, and this concentrated paint is taken out and reused when necessary. In the painting booth after the recycling system has been in operation for a certain period and spray painting is stopped, the booth circulating water is transferred from the booth circulating water tank to the adjustment tank provided for the painting booth. In this adjustment tank, the solvent concentration in the booth circulating water was adjusted by replenishing the water until the volume of the booth circulating water reached a predetermined amount. , The adjusted booth circulating water is transferred to the concentrating tank, and the transfer of the booth circulating water to the adjusting tank and the subsequent replenishment of water in the adjusting tank are performed continuously and separately for each painting booth. A solvent concentration control method in booth circulating water in a water-based paint recycling system is provided.
[0011]
According to the present invention, the adjustment of the solvent concentration in the conventional booth circulating water is a complicated and complicated operation as in the past (for example, as described above, the initial supply amount of the booth circulating water for each coating booth, Record the amount of water evaporation until after the spray coating is stopped separately, etc.), and provide an adjustment tank corresponding to each paint booth. Since it can be implemented by replenishing the booth circulating water transferred from the circulating water tank, not only shortening the work time and improving the operating efficiency of the recycling system, but also reducing the scale of the painting booth including the booth circulating water tank For this reason, it is possible to reduce the size of the recycling system.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
The solvent concentration management method in the water-based paint recycling system of the present invention can be performed, for example, in a normal recycling system as shown in FIG. The recycling system generally includes a water curtain type painting booth 1 in which a painting gun 2 is installed, but the present invention is particularly applied to a recycling system including two or more painting booths.
Each painting booth 1 (or outside the painting booth 1 if necessary) includes a booth circulating water tank 5 for temporarily storing the booth circulating water 6 to be circulated in the painting booth 1, especially the painting booth. There are two or more (ie, a plurality) of 1s. Downstream of these, the overspray paint 4 contained in the booth circulating water 6 is concentrated and separated, and then the concentration tank 7 and the ultrafiltration device 9 for recycling and the concentrated paint 13 are collected and reused. In general, a concentration coating tank 12 for storing the liquid before the adjustment for the purpose and a filtrate tank 10 for collecting and storing the separated filtrate 11 are usually installed one by one.
[0013]
The method of the present invention is basically applied to a painting booth after the recycling system has been operated for a certain period of time and spray painting is stopped.
In the present invention, an appropriate operation period of the recycling system, that is, the timing of transferring the booth circulating water, is to apply a predetermined number of objects to be coated on the basis of the solid content of the overspray paint captured in the booth circulating water. It is determined as the period required for Here, the solid content of the overspray paint captured in the booth circulating water is as follows: (1) First, from the amount of paint consumed for painting, the amount of paint to be applied per measured object (actual measurement) By subtracting, calculate the amount of overspray paint that is captured in the booth circulating water while painting a single object, and (2) find the product of this amount and the number of objects painted it can.
[0014]
Since the present invention is implemented only with respect to a painting booth in which the spray coating is stopped after the recycling system has been operated for a certain period of time among two or more painting booths existing in the recycling system. Spray painting may continue in the remaining painting booths that do not meet the requirements.
[0015]
In the present invention, after the above period, the booth circulating water in the painting booth where the spray painting is stopped is first adjusted from the booth circulating water tank to the adjustment tanks (for example, in FIG. Transfer to 30 and 31).
[0016]
The adjusting tank which is a characteristic element in the present invention is provided between the booth circulating water tank 5 and the concentrating tank 7 in the aqueous paint recycling system for the purpose of adjusting the solvent concentration of the booth circulating water. It is arranged corresponding to the painting booth. Here, “corresponding to each booth” means that there is at least one adjustment tank capable of receiving the booth circulating water of each painting booth. There may be at least one per piece, or at least one per multiple booths.
[0017]
If the adjustment tank is arranged corresponding to each painting booth, it may be a mobile container such as a container or between the booth circulating water tank 5 and the concentration tank 7. It may be a fixed tank.
In the present invention, in particular, when the adjustment tank is a mobile container, even if there is at least one mobile container corresponding to each painting booth in the recycling system, or a plurality of painting booths are supported. The same mobile container may exist.
[0018]
In the present invention, as shown in FIG. 1, together with a mobile container as the adjustment tank 30, a filtrate storage tank (reference numerals 14 and 24) for use in washing the coating booth is also used as a mobile container. It is also possible to fill the filtrate and move through the recycling system simultaneously with or separately from the conditioning tank.
[0019]
The solvent concentration in the booth circulating water is adjusted by supplying water to the booth circulating water transferred to the adjusting tank until the capacity of the booth circulating water reaches a predetermined amount in the adjusting tank.
Replenishment of water not only replenishes the amount of water that evaporates during the operation of the recycling system, but also increases the solvent concentration in the booth circulating water due to overspray paint captured during the operation of the recycling system. Reduce.
[0020]
The amount of water replenished may be an amount that lowers the solvent concentration in the booth circulating water to an appropriate range, and is preferably used for the initial charging booth circulating water, the coating booth and the filtrate used for cleaning the piping in the recycling system and trapped. This is the amount necessary to make the total amount of overspray paint constant.
As a means for supplying water, for example, in order to indicate the liquid level position of the desired total liquid volume after adjustment, the container wall surface is marked and water is supplied up to that position, or the liquid level at this liquid level position in the container It includes installing a sensor and automatically supplying water.
[0021]
In the present invention, the transfer from the booth circulation water tank to the booth circulation water adjustment tank and the replenishment of water to the adjustment tank are performed continuously and separately for each painting booth.
[0022]
Here, “continuously” means that water supply is continued after completion of the transfer of the booth circulating water. Therefore, for example, when the booth circulating water is transferred to the adjustment tank and then the painting booth is washed with water supplied to the painting booth or with a separately prepared filtrate, the contents in the booth circulating water tank increased by the washing are also increased. Like the circulating water, it is transferred to the adjustment tank, and after the transfer is completed, water is supplied to the adjustment tank.
[0023]
These operations are performed separately for each painting booth. “Each paint booth” refers only to the total amount of circulating water in the booth circulating water tank in one painting booth (including washing water after washing the painting booth) among the painting booths that meet the above period and conditions. Means that
That is, in the present invention, after the total amount of booth circulating water in one painting booth is transferred to the adjustment tank and the solvent concentration is adjusted by supplying water to the adjustment tank, the booth circulating water in another applicable painting booth It is characterized by shifting to the total amount of processing, and even when there are two or more applicable coating booths, they are processed individually or sequentially or simultaneously.
[0024]
The adjusted booth circulating water is transferred from the adjusting tank to the concentrating tank and stored until necessary. The means for transferring the adjusted booth circulating water from the adjustment tank to the concentration tank may vary depending on the form of the adjustment tank. For example, if the adjustment tank is a mobile container such as a container, the method includes moving the mobile container from the adjustment tank to the concentration tank, and then transferring the adjusted booth circulating water to the concentration tank. Alternatively, when the adjustment tank is a fixed container, a pipe is installed between the adjustment tank and the concentration tank, and the adjusted booth circulating water is transferred to the concentration tank through the pipe.
[0025]
Furthermore, the method of the present invention can also be applied to a recycling system in which the settling tank 15 is arranged. As shown in FIG. 1, the settling tank is usually disposed between the adjustment tank 30 and the concentration tank 7, and before the adjusted booth circulating water 8 is transferred to the concentration tank and subjected to concentration separation. Its primary purpose is to store it. When a settling tank is arranged in the recycling system, all the adjusted booth circulating water 8 is transferred to the settling tank 15 for temporary storage, and transferred from the settling tank 15 to the concentration tank 7 when necessary. The
[0026]
In particular, when the adjustment tank is a fixed container, a pipe is installed between the adjustment tank and the settling tank, and the adjusted booth circulating water is transferred to the settling tank through the pipe. Therefore, the volume of the settling tank is preferably an amount that can accommodate the adjusted total amount of booth circulating water that can result from two or more painting booths (eg, all painting booths) located in the recycling system. obtain.
[0027]
If the timing for transferring the adjusted booth circulating water from the adjusting tank to the settling tank matches the timing for transferring from the settling tank to the concentrating tank, the adjusted booth circulating water is settling from the adjusting tank. It can be transferred directly to the concentration tank via the tank, more preferably without going through the settling tank.
Here, the timing of transfer from the settling tank or the adjustment tank to the concentration tank is when the ultrafiltration device is stopped and the concentration and separation work is stopped, and is sent to the concentration tank first. After the contents have been concentrated and separated through an ultrafiltration device and separated into a concentrated paint for reuse and a filtrate that can be used for washing, the contents are transferred to a concentrated paint tank and a filtrate tank, respectively.
[0028]
The contents in the concentration tank are separated into concentrated paint and filtrate by repeatedly performing separation and concentration using an ultrafiltration device as necessary. The concentrated paint is then stored in a concentrated paint tank and can be removed and reused as an aqueous paint when needed. Thereafter, the filtrate is mainly sent to the booth circulating water tank and reused for cleaning the painting booth.
[0029]
【Example】
The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In particular, the equipment and the number of tanks and the like in the recycling system shown in the embodiments are merely for explaining the present invention, and may be changed as necessary.
Example 1
This embodiment shows, as one aspect of the present invention, a solvent concentration management method in booth circulating water in a water-based paint recycling system, which includes adjusting the solvent concentration in booth circulating water in a container (movable container) 30. .
In the water-based paint recycling system shown in Fig. 1, the water-based paint 20 is spray-coated on the object in the water curtain painting booth 1, and the overspray paint that has not been applied to the object is sprayed by the booth circulating water. The process of collecting in the booth circulating water tank is repeated until the coating of a predetermined number of objects to be coated is completed. After the spray coating is stopped, the booth circulating water is transferred from the booth circulating water tank to the containers 30 and 31 functioning as the adjusting tank.
[0030]
In this embodiment, one container 30 and 31 is arranged for each painting booth. First, from the booth circulating water tank in the first painting booth 1a, the first booth circulating water (V_a1) Is transferred to the container 30 (step (1) in FIG. 1), and then water or filtrate (in FIG. 1, the filtrate 11 in the washing filtrate storage tank 14) is prepared separately. 1 Wash the interior of the painting booth 1a and collect water or filtrate (V_a2) Is also transferred to the container 30 (steps (2) to (3) in FIG. 1). After the transfer is completed, the total liquid volume (Vx) in the container 30 is V_a1+ V_a2The ideal total liquid volume is Vy = Vx + α₁(Where the liquid volume α₁Represents the amount of water lost due to evaporation, etc. in the surrounding environment during painting and during the transfer and washing of booth circulating water). Therefore, α₁The water concentration in the booth circulating water is optimized by replenishing the container 30 with water to make the total liquid amount Vy. Thereafter, all the adjusted booth circulating water in the container 30 is transferred to the settling tank 15. In parallel with the replenishment of water to the container 30 and the transfer to the settling tank 15, the filtrate 11 is replenished from the filtrate tank 10 into the washing filtrate storage tank 14.
[0031]
At the same time as or before or after the adjustment of the solvent concentration in the booth circulating water related to the first coating booth 1a, processing related to the booth circulating water in the second coating booth 1b is performed as described below. As with the first painting booth, the second booth circulating water (V_b1) Is transferred to the container 31 (process (1) 'in FIG. 1). As in the previous steps (2) to (3), the second coating booth 1b is washed with the filtrate 11 in the washing filtrate storage tank 24 and then recovered (V_b2) It is transferred to the container 31 (process (2) 'to (3)' in FIG. 1). After the transfer is completed, the total liquid volume (Vx ′) in the container 31 is V_b1+ V_b2The ideal total liquid volume is Vy ′ = Vx ′ + α₂As in the case of the first painting booth, α₂The water concentration in the booth circulating water is optimized by replenishing the container 31 with water to make the total liquid amount Vy ′. Thereafter, all the adjusted booth circulating water in the container 31 is transferred to the settling tank 15. In parallel with the supply of water to the container 31 and the transfer to the settling tank 15, the filtrate 11 is replenished from the filtrate tank 10 into the washing filtrate storage tank 24.
[0032]
Concentrated paint 13 and filtrate are obtained by transferring the necessary amount of the booth circulating water 8 stored in the settling tank 15 to a desired amount to the concentration tank 7 and repeating the separation / concentration process by the ultrafiltration device 9. 11 is obtained. The concentrated paint 13 is transferred to and stored in the concentrated paint tank 12, taken out when necessary, and reused as an aqueous paint 20 for spray coating. On the other hand, the filtrate 11 is stored in the filtrate tank 10, taken out as necessary, and used to wash the coating booth.
[0033]
Example 2
In Example 1, although the case where one adjustment tank was prepared for every coating booth was shown, in this Example, the case where it is prepared in the ratio of one for every two coating booths is represented. First, from the booth circulating water tank in the first painting booth 1a, the first booth circulating water (V_a1) Is transferred to the container 30 (step (1) in FIG. 2), and then the water or filtrate (in FIG. 2, filtrate 11 in the washing filtrate storage tank 14) is prepared separately. 1 Wash the interior of the painting booth 1a and collect water or filtrate (V_a2) Is also transferred to the container 30 (steps (2) to (3) in FIG. 2). After the transfer is completed, the total liquid volume (Vx) in the container 30 is V_a1+ V_a2The ideal total liquid volume is Vy = Vx + α₁Because α₁By replenishing the container 30 with water to make Vy, the solvent concentration in the booth circulating water is optimized.
[0034]
Subsequently, the container 30 filled with the booth circulating water from the first painting booth 1a and the washing filtrate storage tank 14 adjusted as described above are moved to the booth circulating water tank in the second painting booth 1b, The second booth circulating water (V_b1) Are further transferred to the container 30 (step (4) in FIG. 2), washed with water or filtrate in the same manner as the previous steps (2) to (3), and then recovered (V_b2) Transfer to the container 30 (process (5) to (6) in FIG. 2). After the transfer is completed, the total liquid volume (Vx ′) at the second painting booth in the container 30 is V_b1+ V_b2The ideal total liquid volume is Vy ′ = Vx ′ + α₂As in the case of the first painting booth, α₂By further replenishing the container 30 with water for Vy ′, the solvent concentration in the booth circulating water is optimized. As a result, the container 30 is filled with the circulated water adjusted to Vy + Vy ′ as a total amount. Thereafter, all the adjusted booth circulating water in the container 30 is transferred to the settling tank 15. In parallel with the replenishment of water to the container 30 and the transfer to the settling tank 15, the filtrate 11 is replenished from the filtrate tank 10 into the washing filtrate storage tank 14.
[0035]
Concentrated paint by transferring the necessary amount of the booth circulating water 8 stored in the settling tank 15 to a desired amount to the concentration tank 7 and repeating the separation / concentration process using the ultrafiltration device 9. 13 and filtrate 11 are obtained. The concentrated paint 13 is transferred to and stored in the concentrated paint tank 12, taken out when necessary, and reused as an aqueous paint 20 for spray coating. On the other hand, the filtrate 11 is stored in the filtrate tank 10, taken out as necessary, and used to wash the coating booth.
[0036]
Example 3
In this embodiment, as shown in FIG. 3, another embodiment of the present invention is a water-based paint recycling system in which piping for transferring booth circulating water is arranged between individual adjustment tanks and settling tanks. Represents the case of performing in
In the same manner as in Example 1, after spraying a predetermined number of objects to be coated with a water-based paint and stopping the spray painting, first, the first booth circulating water in the first painting booth 1a 1 Transfer to adjustment tank 30 for painting booth (in Fig. 3, (1); V_a1). Next, after the coating booth 1a is washed with the filtrate 11, the washing liquid is also transferred to the adjustment tank 30 ((2) to (3) in FIG. 3; V_a2).
[0037]
Total volume of the first booth circulating water and filtrate transferred (Vx = V_a1+ V_a1) Is the amount of water α evaporated and lost in the painting and cleaning process, as in Example 1.₁The amount of water α is the same as the amount of water₁Is replenished to the adjustment tank 30, and the amount of liquid in the adjustment tank 30 is returned to the ideal amount (Vx + α¹= Vy). Thereby, the adjustment of the solvent concentration in the first booth circulating water is completed.
Thereafter, all the adjusted booth circulating water in the adjustment tank 30 is transferred to the settling tank 15 through the piping 40 arranged between the adjustment tank 30 and the settling tank 15.
[0038]
Simultaneously with or before or after the processing related to the first painting booth, the second booth circulating water in the second painting booth 1b is transferred to the adjustment tank 31 through the pipe in the same manner as above ((1) 'in FIG. 3; V_b1) After washing the second coating booth 1b with the filtrate 11, the washing liquid is also transferred to the adjustment tank 31 (in FIG. 3, (2) 'to (3)'; V_b2). Next, in order to make up for the shortage of liquid lost due to water evaporation or the like, water is supplied to the adjustment tank 31 and the solvent concentration is adjusted to an appropriate range for adjustment. After the adjustment, the entire contents of the adjustment tank 31 are transferred to the settling tank 15 through the pipe 41. Thereby, the first and second booth circulating water 8 whose solvent concentration is adjusted by replenishing water in the adjusting tanks 30 and 31 are stored in the settling tank 15 together.
Thereafter, if necessary, the adjusted booth circulating water 8 in the settling tank 15 is transferred to the concentration tank 7 and subjected to a separation / concentration step by the ultrafiltration device 9, whereby the concentrated paint 13 and the filtrate 11 are obtained. can get. The concentrated paint 13 is transferred to and stored in the concentrated paint tank 12 and can be removed and reused as a water-based paint 20 for spray coating, while the filtrate 11 cleans the paint booths 1a and 1b as required. Use to do.
[0039]
In the present embodiment, the adjusted booth circulating water 8 is transferred through the pipes 40 and 41. Therefore, as compared with the first and second embodiments, it is not necessary to secure the scale of the apparatus and the transport path of the movable container. However, in addition to the painting booth, a piping cleaning process is required.
[0040]
【The invention's effect】
According to the present invention, since the solvent concentration in the booth circulating water can be adjusted only by replenishing water, it is not necessary to record the amount of booth circulating water generated from each painting booth as needed, and the operation is very This makes it easier to operate the recycling system more stably and efficiently.
In the present invention, piping from the booth circulating water tank to the adjustment tank is installed using a movable container such as a container, or between the adjustment tank and the concentration tank or between the adjustment tank and the settling tank. Therefore, it is possible to improve the degree of freedom in designing a water-based paint recycling system unit.
[Brief description of the drawings]
FIG. 1 is a schematic process flowchart showing the present invention, characterized in that a solvent concentration in booth circulating water is adjusted in a movable container as an adjustment layer.
FIG. 2 is a schematic process flowchart showing another aspect of the present invention that is adjusted in a movable container as an adjustment tank.
FIG. 3 is a schematic process flow chart showing the present invention, characterized in that piping is used for transferring the adjusted booth circulating water.
FIG. 4 is a schematic conceptual diagram showing an example of a general water-based paint recycling system.
[Explanation of symbols]
1 ... Painting booth, 2 ... Paint gun, 3 ... Water curtain, 4 ... Overspray paint, 5 ... Booth circulating water tank, 6 ... Booth circulating water, 7 ... Concentration tank, 8 ... Adjusted booth circulating water, 8 '... Booth circulating water, 9 ... ultrafiltration device, 10 ... filtrate tank, 11 ... filtrate, 12 ... concentrated paint tank, 13 ... concentrated paint tank, 14, 24 ... filtrate storage tank for washing, 15 ... settling tank, 20 ... aqueous Paint, 30, 31 ... Adjustment tank, 40, 41 ... Piping, 50 ... Workpiece

Claims (7)

Water-based paint was sprayed separately at two or more water curtain painting booths, and overspray paint that was not applied to the objects to be coated was collected in booth circulation water tanks located in each painting booth by booth circulation water. After that, the booth circulating water is transferred to a concentration tank and stored as a concentrated paint by separating and concentrating with an ultrafiltration device. In the aqueous paint recycling system, the concentrated paint is taken out and reused when necessary.
After the recycling system has been operating for a certain period of time and in a paint booth where spray painting has been stopped, the booth circulating water is transferred from the booth circulating water tank to the adjustment tank provided for the painting booth. Then, after adjusting the solvent concentration in the booth circulating water by replenishing water until the volume of the booth circulating water reaches a predetermined amount in the adjustment tank, the adjusted booth circulating water is transferred to the concentration tank. The booth circulating water in the water-based paint recycling system is characterized in that the circulation of the booth circulating water to the adjustment tank and the subsequent replenishment of water in the adjustment tank are performed continuously and separately for each painting booth. Solvent concentration management method. The solvent concentration management method in the booth circulating water according to claim 1, wherein the adjustment tank is a mobile container. The method for managing the solvent concentration in booth circulating water according to claim 2, wherein there is at least one mobile container corresponding to each painting booth. The solvent concentration management method in the booth circulating water according to claim 2, wherein the same mobile container is used corresponding to a plurality of coating booths. The method for controlling the solvent concentration in the booth circulating water according to claim 1, wherein the adjusted booth circulating water is transferred to the concentrating tank through a pipe arranged between the adjusting tank and the concentrating tank. The adjusted booth circulating water is first transferred to a settling tank further arranged between the adjusting tank and the concentrating tank, and then the booth circulating water is settling when the separation and concentration work in the ultrafiltration device is stopped. The solvent concentration management method in the booth circulating water in the recycling system of the water-based coating material in any one of Claims 1-4 including transferring to a concentration tank from a tank. The solvent concentration in the booth circulating water in the aqueous paint recycling system according to claim 6, wherein the adjusted booth circulating water is transferred to the settling tank through a pipe disposed between the adjusting tank and the settling tank. Management method.

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